Spraying fuel directly into a gasoline engines combustion chambers instead of its intake ports isnt a new ideathe World War II ME109 German fighter plane used it. The Japanese-market Mitsubishi Galant was the first car to combine direct injection with computer-controlled injectors in 1996. Direct injection (DI) costs more than port injection because the fuel is sprayed at 15003000 psi rather than 50100 psi, and the injectors must withstand the pressure and heat of combustion. But DI has a key benefit: By injecting fuel directly into the cylinder during the compression stroke, the cooling effect of the vaporizing fuel doesnt dissipate before the spark plug fires. As a result, the engine is more resistant to detonationa premature and near-

explosive burning of the fuel, producing a knocking sound and pounding the pistons with pressure and heatand can therefore operate with a higher compression ratioabout 12:1 instead of 10.5:1. That alone improves fuel economy by two to three percent.

And DI also offers the possibility of lean combustion because the fuel spray can be oriented so that there is always a combustible mixture near the spark plug. That could yield five percent more efficiency. Several European carmakers are already using this lean-burn strategy. Unfortunately, lean combustion causes higher tailpipe emissions of NOx (oxides of nitrogen), which run afoul of Americas tighter limits. Catalysts that can solve this problem dont like the high sulfur content in American gasoline. New catalysts promise to reduce emissions. Meanwhile, expect direct injection to become universal by 2020.

Modern engines achieve power levels that we could only dream about 20 years ago. The downside is that during routine driving, most engines are loafing and 300-hp engines are inefficient when theyre only putting out the 30 ponies needed to push an average sedan down the highway. When an engines throttle is barely cracked open, theres a strong vacuum in

the intake manifold. During the intake stroke, as the pistons suck against this vacuum, efficiency suffers. The classic solution to this problem is to make an engine smaller. A small engine works harder, running with less vacuum, and is consequently more efficient. But small engines make less power than big ones. To make big-engine power with small-engine fuel economy, many companies are turning to smaller engines with turbochargers, direct fuel injection, and variable valve timing. These three technologies work together to their combined benefit. Forcing additional air into an engines combustion chambers with a turbocharger definitely boosts power; car manufacturers have been doing this for years. But in the past, in order to avoid harmful detonation, turbocharged engines needed lower compression ratios, which compromised efficiency. As weve seen, direct fuel injection helps solve this problem by cooling the intake charge to minimize detonation. Second, if the variable valve timing extends the time when both the intake and the exhaust valves are open, the turbocharger can blow fresh air through the cylinder to completely remove the hot leftover gases from the previous combustion cycle. And since the injectors squirt fuel only after

the valves close, none of it escapes through the exhaust valve. The first engine in America with all three of these elements was the base 2.0-liter four-cylinder in the 2006 Audi A4. It had a 10.5:1 compression ratioas high as many naturally aspirated enginesdespite a peak boost pressure of 11.6 psi. It produced 200 horsepower and 207 pound-feet of torque. Fords EcoBoost system is nothing more than direct injection and turbocharging. Dan Kapp, Fords director of advanced powertrain engineering, says that this technology will spread across the companys cars and trucks. Nothing else delivers double-digit improvements in fuel efficiency at a reasonable cost. In the future, Ford expects to replace its 5.4-liter V-8 with a 3.5-liter EcoBoost V-6; its 3.5-liter V-6 with a 2.2-liter EcoBoost inline-four; and its 2.5-liter inline-four with a 1.6-liter EcoBoost inline-four. In each downsizing, peak power should be similar, lowend torque should be about 30 percent greater, and fuel economy should be 10-to-20 percent higher. The only downside will be an added charge of $1000 or so to the price of DI-turbo vehicles to pay for the additional hardware. BMW, Mercedes, Toyota, and Volkswagen are planning similar enginessome

using superchargers instead of turbochargers. Turbocharging with direct injection will continue to expand. Later in the decade, we will see a second generation of these engines, using higher boost pressures. This will allow further engine downsizing to achieve an additional 10-percent efficiency improvement. Making this happen will require cooled exhaust-gas recirculation to control detonation and either staged or variable-geometry turbos to limit customary lag. Those technologies are already in use on diesel engines, but a gas engines higher exhaust temperatures pose durability problems that must be solved before carmakers can deploy these technologies.

Another way to improve the efficiency of a big engine is to turn off some of its cylinders. Since the throttle must be opened farther to get the same power from the remaining cylinders, intake-manifold vacuum goes down and efficiency goes up.

In real-world driving, this can produce a fueleconomy improvement of five percent, at a fairly low cost. The technology is particularly cost effective on pushrod, two-valve engines, which is why weve seen variable displacement on GM and Chrysler V-8s. Honda uses variable displacement on its 24-valve V6 engines, but the additional hardware to close the multiplicity of valves adds cost. Moreover, shutting off some cylinders on a V-6 generates more vibration and noise problems than it does with a V-8 because V-6s have coarser firing impulses and poorer inherent balance. The active engine mounts and variable intake manifolds needed to solve these problems add further costs.

The simplest implementation of variable valve timing started about 25 years ago, using a twoposition advance or retard of either an engines intake or exhaust camshaft to better match the engines operating conditions. Today, most fourvalve-per-cylinder DOHC engines have continuously variable phasing on both the intake and the exhaust camshafts. About 20 years ago, Honda introduced a more elaborate approach with its VTEC system, which shifted between two (and later, three) separate sets of cam lobesone for high-speed operation and one for low. VTEC can also simply turn off one of a cylinders two intake valves under light loads. In 2001, BMW went a step further with its Valvetronic system, which can continuously vary the opening stroke of the intake valves to optimize engine power and efficiency. Furthermore, this extensive control of

the intake valves serves to replace a throttle plate, which eliminates vacuum and therefore reduces pumping losses. Though they provide efficiency benefits, variable-lift systems are complex and expensive. Development continues on purely electronic systems that could replace camshafts and simply open and close an engines valves according to a computer. But electronic valve-opening mechanisms are also costly and consume significant power. GM Powertrain VP Dan Hancock suggests that a two-stage valve-lift mechanism can deliver 90 percent of the benefits of fully variable lift. Moreover, Fords Kapp says that the benefits of variable valve lift are limited when combined with EcoBoost (DI turbo). On the other hand, BMW, with its latest singleturbo, direct-injection 3.0-liter inline-six (N55) thats replacing the twin-turbo (N54) across the lineup, has done just that by adding Valvetronic to its DI-turbo configuration. Combined with the move from a six-speed automatic to an eight-speed, the change is said to provide 10 percent more miles per gallon.

Perhaps the answer will be Fiats Multiair system, a hydraulically operated variable-lift design that is far less complex than mechanical systems such as BMWs. Expect to soon see Multiair on upcoming Chrysler vehicles.

This technology, abbreviated as HCCI, is essentially a combination of the operating principles of a gas engine and a diesel. When high power is required, an HCCI engine operates like a conventional gasoline engine, with combustion initiated by a spark plug. At more modest loads, it operates more like a diesel, with combustion initiated simply by the pressure and heat of compression. In a diesel engine, combustion starts when the fuel is injected with the piston near the top of the compression stroke, and the combustion is controlled by the speed at which the fuel is injected. With HCCI, however, the fuel has already been injected and mixed with the air before the compression stroke begins. Since compression alone initiates combustion, its more of a big bang than even a diesels hard-edged power stroke. Making the engine sturdy enough to avoid blowing apart makes an HCCI at least as heavy as a diesel. The key is achieving sufficient

combustion control so that the HCCI cycle can be used over as wide a speed and load range as possible to reap the efficiency benefits. One way to extend the HCCI mode is to employ a variable compression ratio, which is what Mercedes has done on its experimental Dies-Otto engine. But other engineers, such as GMs Hancock, would like to avoid that complication. To make HCCI work, we need very good control of the combustion process with a faster engine-control computer and combustion-pressure feedback. It all sounds complicated, but the payoff can be a 20percent improvement in fuel economy without the particulate traps and the NOx catalysts that diesels need. Thats enough to sustain interest among the major players. Hancock guesses that HCCI might make it into production by the end of this decade, perhaps as an efficient engine for a plug-in hybrid because it only needs to run over a small rpm band to power a generator.

Turning off an engine when stopped at a light can definitely save fuel. Its easy to program an enginecontrol computer to shut down an engine when the vehicle speed drops to zero and restart it when the driver removes his foot from the brake pedal. The starter and the battery might need to be beefed up to withstand more frequent use, but thats no technical challenge. Mazda has come up with a simpler method of accomplishing the stop-start feat. In its system, called i-stop, the computer stops the engine when one piston is just past the top of the compression stroke. To restart, fuel is injected into the cylinder, the spark plug is fired, and the engine is instantly running again. Unfortunately, while these systems might save as much as five percent of fuel consumption in an

urban setting, the EPAs test cycles demonstrate only a one-percent benefit, due to limited idle times. As a result, most manufacturers are reluctant to invest in a technology that doesnt do much to help them meet their CAFE goals, no matter the real-world benefit.

One of the downsides of corn-based ethanol is that current flex-fuel engines generally arent taking full advantage of E85s 95- octane rating. But its easy to envision a second-generation DI turbo engine that runs higher boost pressure when burning E85. Such an engine could be half the size of a current naturally aspirated powerplant, with substantially higher fuel economy. And when fueled with pure gasoline, the computer would simply dial back the boost. The engine would lose some power but without compromising durability or fuel efficiency.

A more radical way to harness ethanols higher octane rating is the ethanol boosting system (EBS) being worked on by several MIT professors as well as Neil Ressler, Fords former top technology executive. The concept is simple. Start with a DI-turbo engine and add a conventional port-fuel-injection system to it. Then add a second, small fuel tank and fill that one with E85. During modest loads, the engine runs on gasoline and port injection. But when you call for more power and the boost comes up, the DI system injects E85. Not only does E85 have a higher octane rating than gasoline, it also has more cooling effect. This allows safe operation above 20 psi of boost. Ford has shown serious interest in the project. For a pickup application, a twin-turbo 5.0-liter EBS engine might replace the 6.7-liter diesel in the Super Duty truck. It would develop the same power and torque, achieve similar fuel efficiency, and be cheaper to build because it doesnt need any of the diesels expensive exhaust after-treatment. In normal use, E85 consumption would be less than 10 percent of the gasoline consumption. Therefore, you save a lot of gas while consuming only a little ethanol. The EBS engine seems technically sound and has already survived preliminary tests. We

expect that it will make it into production in some form within the next five years.

Imaginative new engine concepts are a dime a dozen. Our technical director usually keeps a fat file full of them labeled crackpot engines. Most never even reach the prototype stage. And even the ones that do get built generally flame out due to problems involving durability, construction complexity, or efficiency. The very few that get beyond that stage face an uphill battle with automakers who have billions invested in building conventional engines of proven reliability and performance. One of the few new engine concepts that looks promising is the OPOC two-stroke from EcoMotors. OPOC stands for opposed piston opposed cylinder. To visualize the engine, start with a horizontally opposed four-cylinder like the Subaru Legacys. Then extend the cylinders and lose the cylinder heads to make room for a second set of pistons within each cylinder that move opposite of the conventional pistons. Long connecting rods transfer the motion of these additional pistons to throws on the crankshaft. As in a typical two-stroke, breathing occurs through ports in the sides of the cylinders. But in the OPOC engine, the intake and exhaust ports are at opposite ends of the cylinders. As the pistons move, the exhausts are uncovered before the intakes and turbochargers blow air through the cylinders to push

out the exhaust gas and fill them with clean air. Since the engine needs positive pressure to do this, the turbochargers have electric motors to power them at low rpm when exhaust energy is low. Though the first OPOC engines are diesels, the concept can also work with gasoline. Either way, the direct-fuel injector is in the middle of the cylinder where the two piston crowns almost meet, and thats where a spark plug would be in a gas version.

If the OPOCs design seems radical, it has solid people backing it. The engine designer is Peter Hofbauer, Volkswagens former chief engine engineer. The EcoMotors CEO is Don Runkle, a former top executive at Delphi and GM. The president is John Coletti, the legendary former boss of Fords SVT division. And exhaust-maker extraordinaire, Alex Borla, is on the board of directors. Much of the companys funding comes from Vinod Khosla, a Silicon Valley mega-investor. Thus far, prototypes of the OPOC engine have delivered 12-to-15-percent better efficiency than conventional piston engines, due primarily to the absence of cylinder heads, eliminating a large surface through which the heat of combustion is lost to the coolant, and the absence of the valvetrain, which reduces friction by some 40 percent. Furthermore, because each two- cylinder, fourpiston module is perfectly balanced, it is possible with a four-cylinder version of the engine to completely decouple one cylinder pair under light loads. This not only reduces pumping losses but also completely eliminates the friction from the disabled cylinder, improving fuel efficiency by an additional 15 percent.

Thus far, Coletti says that there are no obvious problems: Emissions look good, and so does oil consumption. Theres nothing that has me worried. Runkle adds that due to the fewer partsno heads or valvetrainthe engine should be 20-percent cheaper to build than a modern V-6. Were working on two engine families. The EM100d is a diesel with a 100millimeter bore developing 325 horsepower, and the EM65ff has a 65-millimeter bore and makes about 75 horsepower in two-cylinder form on gasoline. The engine is years away from production. For a small, growing company without a huge investment in conventional enginesthink Chinese or Indian the OPOC engine is attractive. A military contract would also pave the way toward civilian acceptability.

As mentioned, being able to change a running engines compression ratio would help to make HCCI work. Most such schemes involve somehow changing either the stroke of an engines piston or the distance from the crankshaft to the combustion chamber. Both approaches are mechanically problematic. The clever engineers at Lotus have come up with a simpler way to change an engines compression. Theyve created a cylinder head that has a movable sectionthey call it a puckthat can extend into the combustion chamber. With the puck fully retracted, the compression ratio is 10:1. When extended into the head, it reduces the combustionchamber volume, thereby increasing the ratio to as high as 40:1. Theres room for this puck because the engine, which Lotus calls Omnivore, is a twostroke without any valves. Instead, intake and exhaust flows occur through ports in the cylinder walls. Fuel injection occurs directly into the cylinder

via an air-assisted system developed by Orbital for a different two-stroke engine the company has been working on for about 30 years. Lotus claims that the Omnivore engine can operate extensively in HCCI mode and achieves a 10-percent fuel-efficiency gain over current DI-gasoline engines. Due to the variable compression ratio, it can also operate on a variety of fuels, hence its name. At this point, the engine is only a single-cylinder research project. Clever, but whether it will advance further remains to be seen.

Fiat's Multiair Valve-Lift System Explained Fiat's Valve-lift system boosts power and saves fuel. Surging gas prices and impending regulations are causing automakers to hunt for ways to increase the efficiency of gasoline engines. One of the chief inefficiencies of these engines is the restriction thats created by the throttle plate in the intake passage, which is used to regulate how much air feeds the cylinders. Referred to as pumping losses, this

bottleneck caused by a partially open throttle forces an engine to squander about 10 percent of energy that could otherwise be used for propulsion. BMW, Nissan/Infiniti, and Fiat have overcome much of these pumping losses by instead throttling their engines via the intake valvesvarying their lift and the amount of time the valves are open to control the engine. BMW was first, with its Valvetronic technology, which was launched on various models in 2001. Its a complex system that uses an additional electronically actuated camshaft to vary valve lift.

The beauty of Fiats Multiair system is its simplicity; it essentially achieves what Valvetronic does by using hydraulic fluid running through narrow passages connecting the intake valves and the camshaft so the two can be decoupled. This system is modulated by an electronically controlled solenoid, and there are effectively two modes: When the solenoid is closed, the incompressible hydraulic

fluid transmits the intake-cam lobes motion to the valve, as in a traditional engine. When the solenoid is open, the oil bypasses the passage, decoupling the valve, which then closes conventionally via spring pressure. For example, to shut the valves early, as in a part-load situation, the solenoid would be closed initially and

then open partway through the intake cycle. The tricky business is correctly timing the switching of the solenoid, and Fiat has painstakingly optimized the responsiveness of the electronic controls. Aside from the fuel-economy and emissions benefits, Fiat claims Multiair can also enable a 10-percent horsepower boost. This technology will go into production in Europe later this year on a 1.4-liter turbo and will also be used on naturally aspirated engines as it spreads throughout Fiats lineup. View Photo Gallery

Camshafts Internal Combustion Engine - Three-Way Cam Lobe Shootout Are Roller Cams Worth It? Should You Just Run A Flat Tappet? We'll Show You In Our Shootout. Camshafts are one of the most confusing components in an internal combustion engine. What makes those lumpy bumpsticks even more confounding is the sheer number of grinds available, and then multiply that by flat-tappet hydraulic, hydraulic roller, and mechanical roller. With all those choices, how do you go about choosing a cam? While you could use the dartboard approach, in this age of computer simulators there's just no excuse for not arming yourself with the right information. That's what we're going to dive into here. To play out our dartboard analogy, consider that once you've read this story, that ancient finned dart has just become a laser-guided missile that will home right in on your next cam selection.

We chose three cams with almost identical duration numbers to use as our test mules to com It seems there is plenty of misinformation when it comes to comparing and contrasting a hydraulic flattappet cam with a hydraulic or mechanical roller. All three offer different valve lift potential, yet there should be a way to compare them on a level playing field. We huddled up with Comp Cams' chief cam designer, Billy Godbold, and came up with a camshaft from each of those different follower families that all share a very close kinship with duration at 0.050 inch, so that's what we chose as our common denominator. Now right away, you're going to look at the cam specs box and think we're off our rocker arms because the numbers don't match up. See, that's where it gets complicated.

You're gonna have to read all the solid tech stuff to understand what we're doing here. Don't skip over the details or you'll miss something important. And while you're at it, eat your vegetables too.

Cam Basics Since there are readers new to this magazine every month, let's quickly roll through some camshaft basics to bring everybody up to speed. There are several ways to evaluate any camshaft, so we'll start with the simplest: lift. A cam lobe is nothing more than an eccentric on a shaft that rotates to create lifter movement. Lift is created when the lobe moves off its base circle, pushing up on the lifter. This lobe lift is multiplied by the rocker ratio to create total

valve lift. As an example, with 0.330 inch of lobe lift multiplied by a 1.5:1 rocker ratio, the valve lift would be 0.495 inch. Perhaps the most informative portion of lobe specs is duration, which is expressed in terms of crankshaft degrees. Duration is also most often delivered in terms of either advertised duration or duration at 0.050 inch of tappet lift. To be totally accurate, any duration spec should be accompanied by the amount of tappet lift where the duration is measured. This rarely happens with advertised duration, but we can tell you that Comp Cams measures both its hydraulic flat-tappet and roller camshafts at 0.006 inch of tappet lift.

Setting lash on any engine is relatively easy. The best procedure is to warm the engine an

Where all this information can get confusing is when we move to mechanical lifter camshafts, either flattappet or mechanical roller, and talk about valve lash. Published cam specs are based on the numbers generated by the cam lobes and their effect on the valve. All mechanical lifter camshafts require a clearance between the rocker arm and the valve to account for expansion as the engine warms up. In the case of our XR286R roller cam, the intake lash or clearance is 0.016 inch with the engine hot. Lash affects most of the published cam specs. The 0.576-inch gross intake valve lift figure on the cam card does not take into account the lash. This means we must use the equation 0.576 - 0.016 = 0.560 inch to come up with our actual net valve lift number. It's a small point, but worth noting for accuracy. Lash also has an effect on duration. According to Comp Cams, the net change is that 0.001 inch of

lash shortens the actual cam duration by 0.5 degree. So with a 0.016-inch lash on the intake, this effectively shortens the intake duration at 0.050 inch checking height by 8 degrees, creating a net duration of 240 degrees at 0.050 inch tappet lift. This explains why we chose a 248 at 0.050 roller cam, because the net duration after lash is actually 240 degrees. CAM SPECS Cam Adv. Duration Lift Lobe Duration @ 0.050 Separation XE284 flat 284 240 0.507 110 hyd., int. PN 12250-3, 296 246 0.510 exh. XR294HR, hyd. 294 242 0.540 110 roller, int. PN 12-43300 248 0.562 8, exh. XR286R 286 248 0.576 110

mech. roller, int. PN 12772-8, 292 252 0.582 exh. Lash: 0.016 int., 0.018 exh. Why Roller Cams Are Better This is some serious stuff, so you'll need to get rid of your normal distractions for a few minutes. It is possible to accurately compare a hydraulic flattappet cam with a hydraulic roller or even with a mechanical roller cam, but there are some important stepping stones to getting there. To begin with, all cams are rated for duration, based on the lobe profile and expressed in crankshaft degrees. For example, lift is expressed on the cam card in terms of valve lift using the stock rocker ratio. But what we should really be looking at with any style camshaft is the duration of valve opening. According to Comp Cams, the best way to rate a hydraulic lifter cam at the valve is to assume 0.004 inch of lifter piston

bleed-down before the lifter begins to move the valve through the rocker arm ratio. In our chart the duration number 283 degrees indicates that the XE flat-tappet cam measures cam lobe duration at 0.006 inch of lifter rise (advertised duration), while the second column indicates that after 0.004 inch of tappet bleed-down and the lobe multiplied by the 1.5:1 rocker ratio, the duration at the valve is actually 282 degrees at 0.006-inch tappet lift.

You can't tell much about a cam by looking at it. Even the two roller cams look much the s We can use that same 0.004-inch lifter deflection figure to rate hydraulic roller cams. Notice that despite the fact that the flat-tappet and the hydraulic roller cams are only 2 degrees apart at 0.050 inch of lobe lift (240 versus 242), the hydraulic roller offers 5

more degrees of duration at the valve at 0.200 inch of lobe lift and an impressive 16 more degrees of duration at the valve at 0.400-inch lobe lift (from 107 to 123 degrees). This indicates the higher lifter speed capability of the hydraulic roller design over the hydraulic flat tappet. So while at 0.050 these cams appear the same, this number by itself is deceiving. Looking at a basic lift curve, the hydraulic roller achieves a given lobe lift such as 0.200 inch much more quickly and therefore creates more area under the valve lift curve. This means more air and fuel will enter the cylinder to make more power. Now let's look at the mechanical roller lobe. Mechanical lifter camshafts are more difficult to evaluate because you should not use advertised duration as an indicator for several reasons. First, because of 0.016 inch of lash (clearance between the rocker arm and the valve), a lobe duration number measured at 0.006-inch tappet lift is

meaningless because at a rocker ratio of 1.5:1, that 0.006-inch lobe lift number is worth 0.009 inch of movement at the rocker tip, which is still short of taking up the 0.016 inch of clearance. Even at 0.050 inch of lobe lift (duration at 0.050), this calculated number of 253 degrees of duration does not take into account the lash. Going back to Godbold's rule of thumb, every 0.001 inch of tappet lift is worth roughly half a degree of duration. In order to account for our rated 0.016 inch of lash, we must remove 8 degrees from the 0.050-inch duration figures, which means the 248 degrees at 0.050 is really 240 degrees and therefore exactly the same lobe duration at 0.050-inch tappet lift as the flat-tappet hydraulic camshaft. But notice the tremendous velocity the mechanical roller cam can generate throughout the entire lift curve, offering up a serious 197 degrees at 0.200-inch lobe lift. Compared to the hydraulic roller and flat-tappet cams, you can see why the mechanical roller is superior. At the

extreme, the mechanical roller offers a staggering 21 more degrees of duration at 0.400-inch lobe lift than the hydraulic flat-tappet cam, and 5 more degrees than even the hydraulic roller (123 versus 128). What this means is that the intake valve is held open at the same valve lift for a much longer period of time within the cycle from when the valve first opens until it closes. This is why the mechanical roller cam can make more power than the hydraulic flat-tappet. Because of additional duration and greater lift, the mechanical roller lifter is traveling faster than its more conservative hydraulic counterparts, which is why lighter components and stiffer valvesprings must be part of the overall package. 294XE 284XE Hyd. Hyd. Flat Roller Lobe Lobe Lift Dur. Valve Lobe Dur. Valve 286XE R Mech. Roller Lobe Valve Dur. Dur.

Dur.

Dur. @ 1.5:1 (0.01 6 lash)

@ 1.5:1 @ 1.5:1 (w/ 0.004 (w/ 0.004

deflectio deflectio n) n) 0.00 283 6 0.01 268 5 0.05 240 0 0.20 153 0 0.40 0 282 271 250 190 107 294 276 242 164 292 (+10 ) 280 (+9) 253 (+3) 195 (+5) 123 (+16 ) 30 285 9 (+3) 28 5 24 8 17 0 276 (+5) 253 (+3) 197 (+7) 128 (+21 )

The numbers in parentheses for valve duration at 1.5:1 for both the 294XE hydraulic and the 286 XER

are the number of degrees of difference compared to the 284XE hydraulic flat-tappet cam.

Valvesprings need to be carefully matched to the specific camshaft in order to obtain maxi Why You Need To Upgrade The Valvesprings This chart is easy to understand once you know a little bit about valvesprings. Load at installed height refers to the amount of pressure in pounds created by the spring with the valve closed at a given installed height. The installed height is the distance from the bottom of the retainer to the spring seat location on the cylinder head. Load at maximum lift is the pressure created by the spring across the nose of the cam at its greatest valve opening. The spring rate is the amount of load in pounds created for every inch of travel the spring is compressed. If

you know the load at both the closed and open points, you can determine the rate. Subtract the installed load from the open load and then multiply by the lift ratio (lift ratio = 1 divided by the max valve lift). Using the 939 spring as an example: 420 - 167 = 253 x 1.85 [1 1/4 0.540 lift = 1.85] = 468 pounds per inch (lb/in) spring rate. Coil-bind refers to the height of the spring when it is fully compressed. It's critical that the engine builder allow a minimum of 0.060 inch of clearance to coil-bind. We chose spring pressures higher than Comp's recommendations to ensure that the valvetrain would not go into valve float during testing. Note the radical increase in seat pressure for the mechanical roller spring application. The hydraulic flat-tappet and roller springs both use a seat load of roughly 160 pounds. But when we get to the mechanical roller springs, the seat pressure jumps to 240 pounds at the same installed height. That's a

50 percent increase in seat pressure and a 59 percent increase in load at max lift. This is necessary in order to fully control the much higher acceleration rate and valve velocities achieved by the mechanical roller lobe working on the valves. As these opening and closing rates increase, they create much larger forces on the valve that must be controlled by the valvesprings. Load Load @ Rate CoilValvespring @installed max (lbs./in.) bind(in.) ht. lift 330 Comp PN 153 @ @ 354 1.160 928, dual 1.900 0.500 420 Comp PN 167 @ @ 468 1.225 939, dual 1.900 0.540 Comp PN 943, dual 557 @ 1.150 240 @ 0.575 551 1.900

Each cam required a spring change to allow us to get the most performance out of each cams Three Springs for Three Cams It would be nice if all the moons and stars aligned in the engine-building world so that one valvespring would work for all applications. Perhaps back in the '20s that was the case, but not now. Because we have three completely different cam designs in a flat-tappet, a hydraulic roller, and a mechanical roller, all three require their own design valvespring. Spring pressure is critical to ensure that the valve is always controlled by the camshaft. Valve float is a common term referring to a loss of control, but for most engines the first sign of trouble is when the intake valve bounces off the seat on the closing portion of the lift curve. This allows cylinder pressure

to escape back into the intake manifold, reducing power. Eventually the engine will begin to pop and bang, sounding like an ignition misfire, when in reality it is the valvesprings that have failed. Increasing the spring rate is the most popular solution to this problem, but another fix is to either reduce the rocker arm ratio or reduce the weight of the rocker arm side of the valvetrain, as with titanium retainers. Another excellent investment is thickerwalled pushrods. For small-block Chevys, 0.080inch-wall-thickness, 51/416-inch-diameter pushrods are very common, but they do cost more. Stronger pushrods tend to deflect less, which reduces the pole-vault effect that can occur at high rpm when the pushrod bends and then launches the lifter over the nose of the cam. The problem with increasing spring pressure with a flat-tappet camshaft is that too much pressure can literally wipe the lobe right off the cam. This is

especially critical during camshaft break-in. For our engine, using the 928 dual springs required us to remove the inner spring for break-in and then install the inner springs after the cam had established its wear pattern. Even then we added extra insurance by using Comp Cams' break-in lubricant, which offers a higher zinc additive package to reduce initial wear on the new cam. When it comes to longerduration hydraulic, flat- tappet, and hydraulic roller camshafts, the valvespring question becomes a delicate balancing act between maintaining sufficient spring pressure to control the valves at higher engine speeds and avoiding excessive spring pressures that can cause problems.

We also checked pushrod length with each cam change to maintain valvetrain geometry accura

The beauty of a mechanical roller cam is that it allows the luxury of higher spring pressures, but there are difficulties here as well. Increased spring pressures place higher loads on the valvetrain, causing increased wear, not to mention abuse on those tiny roller bearings in the lifters. One reason for increased spring pressure is the higher engine speed that is part of the equation for a long-duration mechanical roller camshaft. We've included a short spring-pressure chart created with help from Westech's Steve Brul that we used to help us determine the best springs for each of the three different camshafts. These are numbers that Brul has found works for him. An interesting question surfaced during this testing relative to how much spring pressure a hydraulic roller cam combination could withstand. Keeping this explanation short and simple, too much spring pressure does not really force the hydraulic lifter

piston down, as is commonly thought. What really happens is that higher spring pressures tend to deflect the pushrod, which causes valvetrain separation at higher engine speeds when the pushrod pole vaults the valve past the nose of the cam. This clearance in the valvetrain allows the lifter piston to pump up. When the cam lobe returns to the base circle, the pumped-up lifter holds the intake valve open and causes the engine to lose power. Reducing hydraulic roller valvespring pressures to more manageable levels reduces pushrod flex and minimizes lifter pump-up. SPRING PRESSURE CHART Seat Lifter Style Pressure (lbs.) Hydraulic flat 150* tappet Hydraulic roller 200 Mechanical 220 roller

Open Pressure (lbs.) 350* 400 575

*After cam break-in. It is advisable to remove the inner spring on any dual-spring package when breaking in a new flat-tappet camshaft. This is not necessary with roller cams. Test Time With all this background tech information jammed into our heads, now it was finally time to put down the theory books and get our hands dirty. The smallblock we decided to beat on was the healthy 383ci we used last month for the giant "Speed Parts Tested" cover story. The engine configuration for this test is a little different but includes 10.5:1 compression from a complete Lunati rotator assembly, a set of Dart CNC 227 heads, a Holley Keith Dorton single-plane intake manifold, and a Barry Grant 850 Mighty Demon carburetor. We started the test with the smallest cam, the Comp Xtreme Energy 284 hydraulic flat-tappet version matched up with a dual-spring package, titanium

retainer, and the appropriate-length pushrods. The flat-tappet cam made respectable peak power at 507 hp at 6,200 rpm and 489 lb-ft of torque at 5,000. The beauty of a flat tappet is its decent power and great torque, all delivered at an affordable price. But now we were looking forward to ramping up the power numbers with the roller cams. The hydraulic roller slid right in along with the taller Comp Cams hydraulic roller lifters. The taller lifters also demand shorter pushrods and, of course, a swap to a stronger set of Comp dual springs, which increase the spring load in order to help control the valves. As we expected, the hydraulic roller made more peak power than the flat tappet along with slightly more torque due to its more aggressive roller lobe design. This helps justify its increased cost. The hydraulic roller jumped the power up to 530 at 6,200 rpm while the torque also grew from 489 to 502 at 5,200. That's a solid 13 lb-ft increase of torque and

23 hp. Also note that both hydraulic cams peaked at almost the same rpm for both torque and horsepower. But all this did was motivate us to bolt in the mechanical roller.

Our 383 small-block Chevy test mule consisted of a 383 with a Lunati forged crank, rod, an By now we were getting good at swapping cams, and the motor had barely cooled down before the new mechanical roller was in place and the springs and pushrods swapped once again. With 0.016-inch lash dialed in on the intake, the duration at the valve was exactly the same as the flat-tappet hydraulic cam, yet this mechanical roller setup rocked when it came to peak horsepower. Once we pulled the throttle handle, however, it quickly became apparent that while the peak horsepower was up over the

hydraulic roller, the mechanical and hydraulic roller cam torque curves in the middle were almost identical, something we didn't expect. The mechanical roller's torque peak was actually down 6 lb-ft to 496 at 5,200 compared to the hydraulic roller, but made up the difference at peak horsepower with an impressive 539 at 6,600, which is up 9 hp over the hydraulic roller. The best way to evaluate this test is to look at the power averages for all three cams. Because all three cams were chosen with the same duration at 0.050, there's not a huge difference in power averages between the three. The mechanical roller clearly owns the peak horsepower title with a stout 32hp advantage over the flat tappet. The mechanical roller also is up 12 hp and 11 lb-ft of torque average, which is a significant difference. But let's not overlook how well the flat-tappet cam performed, especially if we factor in the additional cost of either

roller cam package. Of course, there's also the hassle factor of the flat-tappet cam, with both breakin and longevity concerns with current engine lubricants. But the power difference clearly points to the best power-per-dollar choice being with the flattappet cam. Looking at all the data, it would have been interesting to see how a flat-tappet mechanical cam would have fared in this test. If you look at the graph of the three power curves, this may help with the concept of which lifter style cam is the correct one to use. Remember that the easiest way to make normally aspirated horsepower is to make the same torque at a higher engine speed. If you look at the flat-tappet hydraulic horsepower curve, it tends to flatten out at 5,200 rpm, while the two roller cam curves extend peak horsepower well past 6,000. If you plan to only shift your engine at 5,500 rpm or below, there's no reason to spend the extra money for a roller

camshaft since all three cam torque curves up through around 5,200 rpm are very similar. The roller cams deliver far more valve control and rpm potential to make more horsepower. Also notice how the hydraulic roller tends to drop off at around 6,200 while the mechanical roller cam continues to make power up through 6,600. We think that this slight dip in the hydraulic roller curve is probably due to pushrod deflection. Since the price difference between a hydraulic roller and a mechanical roller cam is relatively small, there are opportunities for both styles of cam, especially if your plans include a shorter-duration roller cam that is not going to spin as high an rpm as these 240-degrees-at-0.050duration camshafts. What this test does illustrate is how critical duration is to the power curve since all three cams, regardless of lifter design, are very close in terms of peak torque. Peak horsepower changed the most

between the three cams, but most of that was the change the mechanical roller made by pushing the peak horsepower up to 6,600 rpm. This is also of concern because to take full advantage of a 6,600rpm peak horsepower point, it's generally required to spin the engine another 400 to 500 rpm past peak power to get the most acceleration advantage out of the engine. This means twisting this small-block to around 7,000 rpm. You'd better have a good steel crank, rods, and strong forged pistons if you're gonna spin a small-block 383 to 7,000 rpm! Power By The NumbersTest 1 consisted of the 383 small-block Chevy with the flat-tappet hydraulic Comp XE284 cam. All other components for this test remained the same for all three tests. Test 2 changed to the XEHR294 hydraulic roller cam and dual valvesprings.

Test 3 swapped to the XR286 mechanical roller cam and to a third, higher-load set of dual valvesprings with titanium retainers.

Before bolting the engine on the dyno, we also took the time to check for roller cam endpl The DIFF column represents the difference in power between Test 1 and Test 3. TEST 1 RPM TQ HP 3,000 420 240 3,200 429 262 3,400 430 279 3,600 436 299 3,800 441 319 4,000 448 341 4,200 460 368 4,400 465 390 TEST 2 TQ HP 421 241 429 262 430 278 438 300 445 322 446 340 460 368 467 391 TEST 3 TQ HP 425 243 431 263 434 281 437 300 445 322 446 340 462 370 472 395 DIFF TQ HP +5 +3 +2 +1 +4 +2 + 1 +1 +4 +3 -2 -1 +2 +2 +7 +5

4,600 477 4,800 487 5,000 489 5,200 489 5,400 482 5,600 467 5,800 456 6,000 443 6,200 429 6,400 409 6,600 378 450. Avg. 7 Peak 489

418 476 446 491 466 500 485 502 495 496 498 487 503 478 506 463 507 449 499 431 475 415 460. 412 7 507 502

417 481 449 489 476 494 497 496 510 493 519 486 528 476 529 464 530 452 525 442 522 429 461. 423 7 530 496

422 +4 +4 447 +2 +1 470 +5 +4 491 +7 +6 507 +11 +12 518 +19 +20 526 +20 +23 530 +21 +24 534 +23 +27 539 +33 +40 539 +51 +64 424 +11 +12 539 +7 +32

Note: The average columns take into account power numbers every 100 rpm, which are not listed in this chart.

Power Curves Note how all three camshafts create almost identical power curves through 5,000 rpm. By 5,200 rpm, you can see the hydraulic flat-tappet cam begin to nose over while both rollers continue to make similar power up to 6,000, where the mechanical roller takes over to make the most peak horsepower. PARTS LIST COMPONENT Comp XE 284 hyd. flat Comp XR 294HR hyd. roller Comp XR286R mech. roller Comp hydraulic lifters Comp hydraulic roller lifters Comp mechanical roller lifters Comp rocker, Pro

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PRICE 115.95 255.95 255.95 92.95 509.95 516.99 430.69

Magnum 1.5:1 Comp springs, dual for flat hyd. Comp retainer, for 928, titanium Comp 10-degree keepers Comp dual spring, mech. roller Comp retainer, dual spring, titan Comp springs, dual hyd. roller Comp retainer, titanium for dual Comp pushrods, hydraulic roller Comp pushrods, std. length Comp pushrods, hyd. flat, + 0.100 Comp pushrods, mech. roller Comp timing set

16 928 732-16 611-16 943-16 731-16 939-16 732-16 794916 799216 799316 799516 3100KT

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139.95 299.95 22.88 299.95 299.95 137.39 299.95 145.95 168.69 125.95 135.95 176.69

Comp roller button 211 Comp 3-pc. timing 210 cover Comp shim 4757 package Moroso stud mount 62370 spring tool

Summit Racing Summit Racing Summit Racing Summit Racing

22.39 229.95 25.69 79.95

With the lifters, it's a little easier to tell a flat-tappet hydraulic (right) from the hy

We used titanium retainers on all the springs in this test because of the rather high engi Piezo Fuel Injectors Explained

The Tower of Piezo: The smartest injectors youll ever meet.

February 2011 BY CSABA CSERE

If youve ever seen the sparks created by someone munching Wint-O-Green Life Savers in a darkened room, youll have witnessed this phenomenon: Certain crystalline materials, such as sugar, produce minute amounts of electricity when you squeeze them. Theres even a word for it: piezoelectric, which describes electricity resulting from pressure. But the process is also reversible, in that these same materials expand slightly when electricity is applied to them. There are numerous places in a car where piezoelectric expansion can come in handy. Take, for example, the precise metering necessary for modern-day fuel delivery. Bosch, Continental, and Delphi, among others, have harnessed this peculiar property of expanding piezo material rather than the usual electromagnetto open the fuel-injector nozzle and precisely spray fuel into both gasoline and diesel engines. Making these devices work, however, isnt easy.

One reason is that the expansion of the piezo crystals is minuscule. A slice of piezo material twohundredths of an inch thick expands only about 0.00002 inch when it gets hit with roughly 140 volts of electricity. That two-hundred-thousandths of an inch is not nearly enough to move an injectors pintle, which is the part that seals the nozzle and must open to inject fuel.

The Continental injector has hundreds of little piezo slices stacked on top of each other so that the combined expansion increases the total motion. The stack produces 0.004 inch of movementenough to move the pintle far enough to inject fuel. But because this motion is in the wrong directiondown, not upthe addition of two tiny levers allows the expansion of the piezo stack to cause the pintle to be lifted and the fuel spray to begin. When the injection is complete, the voltage cuts off, the piezo stack shrinks, and a spring closes the pintle. Piezo injectors have a few key benefits that justify all of this bother. For one thing, they open and close much faster than conventional injectors. That makes for more precise control of the injection interval, which determines how much fuel is sprayed into the engine. Piezo units also provide feedback by producing minute fluctuations in the electricity used to activate them. For example, if the engine-control computer calls for an injector-opening time of 0.5 second, and the injector response shows that it opened for only 0.496 second, the computer can add a tiny bit of time to the next injection cycle to compensate. Such precise fuel metering makes for improved combustion, which leads to better fuel economy and reduced emissions.

Not only are piezo injectors more accurate than conventional solid injectors, they also can perform some tricks that are completely beyond the capabilities of their predecessors. For one thing, by applying a little less electricity, the piezo crystals expand less so the injectors can open partway. A smaller opening means a longer injection time, which is beneficial when trying to accurately inject a tiny amount of fuel, such as when a car is nearly coasting. Because they act so quickly, piezo injectors also can inject several times (as many as seven in some diesels) during a single combustion cycle. This flexibility can reduce emissions in all engines as well as limit soot in diesels. These benefits have secured a home for piezo injectors in many of the latest diesel and directinjection gasoline engines. And Continental, for one, says that its piezo units dont cost more than the less capable conventional equivalents. Piezo injectors are one of the key devices that will keep internal combustions competitive against these pesky electric upstarts for years to come.

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Mazda Skyactiv-G and Skyactiv-D Engines in Detail A deep dive into Mazda's new gas and diesel four-cylinders reveals huge fuel-economy gains.

August 2010 BY DAVE VANDERWERP

Around the world, automakers are grappling with the changes necessary to meet escalating fueleconomy regulations. To this end, Mazda is launching a new family of four-cylinder engines fours power the vast majority of Mazdas carscalled Sky-G (gasoline) and Sky-D (diesel). We drove both in prototypes of the next-gen Mazda 6 and, thankfully, either engine can be paired with the latest version of Mazdas snick-snick six-speed manual. We got the deep dive on the 2.0-liter version of the Sky-G, which will launch next year in the U.S., likely as part of a midcycle face lift of the Mazda 6. (A completely new 6 is a few years out yet and will be about 140 pounds lighter than the current car, thanks to meticulous optimization of material thicknesses and mounting points.) In the future, there also will be variations in the 1.3- to 2.5-liter realm, and Mazda has already signed a deal to

license Toyotas hybrid technology for a future Skybased hybrid. Starting from the ground up, Mazda has impressively leapfrogged its previous gas engine, to the tune of estimated EPA fuel-economy ratings in a Sky-equipped Mazda 3 of 30 mpg city and 39 to 40 highway. Thats nearly on par with VWs Golf and Jetta diesels as well as best-in-class cars one segment smaller, such as the Ford Fiesta and Chevrolet Cruze. Heres how they did it. The Big Squeeze Increasing the compression ratioin this case, to a staggering 14:1 from 11:1 in the current 2.0-liter (the U.S. version is 10:1)is a classic way to squeeze more work out of the pistons power stroke. But it creates problems, too, because compressing the air/fuel mixture this much causes excess heat buildup in the cylinder, which leads to premature autoignition, or knock. To keep the temperatures down, Mazda employs a seriously lengthy 4-2-1 exhaust header, designed so that the hot exhaust gases dont get pulled back into the next cylinders intake stroke. As it stands today, it doesnt appear that the Sky could fit in a longitudinal application such as the Miatathe huge header likely would poke through a front fender.

Further improvements include the addition of direct injection and a reduction of heat losstoo much heat can be problematic, but temperature is a necessary byproduct of burning fuel, and squelching it all is inefficient. The heat-loss reduction comes from a smaller bore and a much more complex piston shape that features a cavity directly in the pistons center, the hot area where the spark plug fires. Friction also has been reduced in the pistons, rods, and crankshaft (which is now forged steel instead of cast iron), and roller finger followers reduce it in the valvetrain. The engine uses 0W20 oil, which looks frighteningly like colored water. The Sky also gets dual variable valve timing, electronically varied (as opposed to using oil pressure) on the intake side, so that rapid adjustments can be made even during cold starts. Overall weight has been reduced by about 15 pounds,

including 10 saved by thinning out the block where additional strength wasnt needed. Premium Fuel, Mid-Grade Output Premium, 91-octane fuel is required for the Skys not-so-staggering 163 hp at 6000 rpm and 155 lb-ft at 4000, but Mazda is proud of its exceptionally wide torque band for enhanced real-world drivability. To enable running on regular gas, the U.S. version will have a compression ratio of 13:1, which means fuel economy and torque will diminish by about 3 to 5 percent, according to Mazda. The premium-fueled Sky we drove was perfectly adequate in the Mazda 6 prototypes, although acceleration was rather leisurelyfar slower than the current Mazda 6 with its 168-hp, 2.5-litergiving us plenty of time to wish for a bit more smoothness during the extended time in each gear. But being in the lighter Mazda 3 would help, and the tradeoff for near-diesel levels of fuel economy is probably worth it. Surprisingly, Mazda is passing on todays popular trend of downsized, turbocharged enginessay, a 1.4-liter turbo instead of this 2.0-liter. The company says the next generation of gasoline engines, which will employ HCCI (Homogenous Charge Compression Ignition)essentially firing a gasoline engine like a diesel, without using the spark plugs

will erode the benefits of downsized engines. Smaller engines reduce pumping losses by operating at a higher load (the throttle is open further) more often. In the same way, HCCI engines will have to flow more air to realize the fuel-saving, lean-combustion benefits of that cycle. Mazda claims that if it downsized the Sky family of engines they wouldnt be able to flow enough air for HCCI without upsizing once again. Plus, as Mazda rightly points out, adding a turbocharger and an intercooler is quite a pricey proposition.

Oil-Burner Expos On the diesel side, Mazda has pulled off an even more impressive feat. The 2.2-liter Sky-D (again, other sizes are likely to follow) boosts fuel economy by 20 percent over the current, 2.2-liter diesel and meets Euro 6 and U.S. Tier 2 Bin 5 emissions

standards without using any NOx aftertreatment such as urea injection. You catch that? It meets U.S. emissions standards. Thats because Mazda is planning to bring this engine here sometime in 2012. With the diesel, Mazda moved in the opposite direction, decreasing the compression ratio from 16.3:1 down to 14:1. Thats the same as the gasburning Sky-G, and a value thats the lowest in the world among diesels, according to Mazda. Doing so reduces cylinder pressures, and therefore temperatures, which reduces NOx production and also allows the fuel to mix better, avoiding locally rich areas that produce soot. Mazda claims that the lessened friction from the reduced cylinder pressure alone is worth a 4- to 5-percent gain in fuel economy. And the reduced internal forces also allow components such as the rods and pistons to be substantially lighter. Here, too, a forged steel crankshaft replaces a cast-iron unit. Overall weight savings is a whopping 55 pounds. The downside to lowering the compression ratio of a diesel is that, during warm-up, the engine temperature can be too low to support proper combustion, and misfires result. To get around this, Mazda added a two-stage variable valve-lift system on the exhaust side in order to be able to create additional valve overlap. This causes the hot exhaust

gases to be drawn back into the next cylinder to warm it up.

Eat It, Hybrids Other new features are a sequential twin-turbo arrangementone small and one largewhich outperforms the old single, variable-geometry unit; 12-hole piezo injectors that disperse fuel into the cylinder in exacting quantities during two to eight separate injections per cycle at pressures up to 2900 psi; and an exhaust manifold thats completely integrated into the block. Here, too, fuel-economy claims are impressive: 31 to 33 mpg city and 43 mpg highway for a Mazda 6 with the 2.2-liter diesel. Does an over-40-mpg family sedan sound good to anyone else? Output beats the gas engine in both regards: 173 hp at 4500 rpm and 310 lb-ft at 2000. Redline has been

raised to a screaming (for a diesel) 5200 rpm, versus its predecessors 4500. And it felt notably quicker than the gas-engined car, pulling strongly throughout the rev range and exhibiting none of the run-out-of-breath feeling that afflicts some diesels as they wind toward the upper end of the tach. Its exceptionally responsive, and quiet, too, with very little clatter, even when accelerating from engine speeds below 1500 rpm. Automatic Anxiety In addition to the sweet-shifting six-speed manual, we drove each engine with Mazdas new Sky-drive six-speed automatic, which boasts a more aggressive lock-up clutch for the torque converter, leading to a 4- to 7-percent improvement in fuel economy. Although the calibration was admittedly early in development, the automatic was distinctly less impressive than either of the new engines. In terms of feel, which Mazda claims is much more direct than before, it doesnt seem to stand out from the current crop of high-tech automatics. The wideopen-throttle upshifts struck us as a bit lazy, too, although the downshifts were quite prompt. Well stick with the manual, thank you very much. Few buyers do, however, which could mean bad things for Mazdas sales.

Perhaps the best thing in all of this, though, is that Mazdas impressive engineering work proves that the internal-combustion engine still has plenty of legs in our ever-more-regulated world.View Photo Gallery Ethanol-Injection Systems Explained Driving Under the Influence: Ethanolinjection systems aim to use alcohol responsibly. December 2011 BY DON SHERMAN ILLUSTRATION BY PETE SUCHESKI

Thanks to the adoption of direct fuel injection, teaming gas and ethanol has the potential to beat diesel efficiency. We can hear your groans already: Our federal governments effort to curb oil imports by lacing gasoline with ethanol has been a boon to American farmers but a bust to the driving public. The problem is simple economicspumping E85 (85-percent

ethanol and 15-percent gasoline) into todays flexfuel cars costs more per mile than fueling the same car with regular gas. Were suffering from ethanols detriments without exploiting its advantages. Ethanols balance sheet has been well understood for decades. Because ethanols energy density is roughly 66 percent that of gasoline, mpg suffers when ethanol is used as a straight substitute. On the opposite side of the ledger, ethanol has an octane rating of 100, versus 85 to 100 for gasoline, enabling much higher compression ratios. (Unleaded, 100octane racing gas is expensive and not widely distributed. Readily available premium gas tops out at 94 octane.) And when ethanol changes from liquid to gas on the way to combustion, it absorbs 2.6 times more heat than gasoline, a highly beneficial cooling effect. So how do we take advantage of those attributes to optimize ethanols role in modern transportation? The history books are a good place to start. During World War II, BMW and Daimler-Benz sprayed methanol and water mixtures into their supercharged aircraft engines to forestall detonation (premature ignition of the fuel-air charge). In the U.S., a postwar GM applied similar research in its 1951 LeSabre dream car, which was powered by a supercharged V-8 capable of running on gas or

methanol. That paved the way for the 1962 Oldsmobile F-85 Jetfire, the worlds first turbocharged production car, which used TurboRocket Fluida mix of water, methanol, and rust inhibitorto skirt detonation with a then-ambitious 10.25:1 compression ratio and 5.0 psi of boost. Todays racers use all manner of fluidswater, alcohol, nitromethane, lead substitutes, and nitrous oxidein pursuit of power. Theres also a government-backed experiment at Chrysler aimed at running both gasoline and diesel fuels through the same engine. But the most sensible approach for the public at large is to use technology now in hand to achieve significant mpg gains. The tech? Gasoline, E85, and direct fuel injection. British-based Ricardo and Ethanol Boosting Systems (EBS) of Cambridge, Massachusetts, both have E85fueled engines under test that deliver diesel efficiencyat least 30-percent better than a typical gas enginewithout the need for cumbersome, ultrahigh-pressure fuel-injection and exhaust-treatment equipment. Both firms propose aggressive turbocharging, a 12.0:1 or higher compression ratio, and about half the normal piston displacement. Ricardo uses an octane sensor, variable valve lift, and variations in

valve and ignition timing to take maximum advantage of any ethanol pumped into the fuel tank. EBS adds a second complete fuel system that enables an engine to run on port-injected gas during cruising and direct-injected E85 only during full-load conditions to spare its consumption. Heavy-duty pickups are the first candidates for this technology. Both EBS and Ricardo pitch their ethanol-based systems as diesel fighters capable of delivering 600 or more pound-feet of torque at low rpm from a 3.0-liter engine. Assuming that manufacturers agree with these ethanol boosters, the dual-fuel strategy could be handy for meeting the 35.5-mpg CAFE standard for 2016. By then, fourcylinder performance cars will be commonplace, and theyll definitely be thirsty for all the Turbo-Rocket Fluid they can get.

Drinking in the 60s As noted, the 1962 Oldsmobile F-85 Jetfires V-8 (right) tried this whole multifuel thing a while back. The turbocharged 3.5-liter engine, eating five pounds of boost, made 215 horsepower and 300 pound-feet of torque. If the reservoir of Turbo-Rocket

Fluid ran out, a mechanical system would automatically reduce the amount of boost to avoid detonation. In our test of a 1963 F-85 Jetfire, we recorded a 0-to-60 time of 8.5 seconds, with the quarter-mile falling in 16.8 seconds. The system proved problematic, and over two years GM put fewer than 10,000 of these engines on the road. Other Stories You Might

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Ricardo Announces a Better Way to Use Ethanol Ricardos high-boost, 400-hp V-6 may replace massive diesels in heavy-duty pickups.

February 2009 BY DAVE VANDERWERP

A couple years back, there was a big marketing push for E85 fuel85 percent ethanol, 15 percent gasoline but little reason why anyone would want to use it.

E85 currently costs about 10 percent less than regular gasoline in most areas, but because of its lower energy content delivers a 30-percent reduction in fuel economy. Its no wonder the vast majority of the millions of E85-capable, flex-fuel vehicles on the road never burn the stuff. The reason these flex-fuel vehicles exist is a regulatory loophole that allows the automakers to boost their fleet fuel-economy average (CAFE) because the government only counts the 15 percent gasoline content when calculating mileage. A flex-fuel Chevy Tahoe, for example, received an absurd 97-mpg E85 rating, which boosts that all-important CAFE number. Engineering firm Ricardothe company responsible for the seven-speed dual-clutch automated manual in the 1001-hp Bugatti Veyronhas somewhat loftier goals for ethanol. Its working on a 3.2-liter V-6 engine that could replace a large turbo-diesel V-8 in a heavy-duty truck application. Ricardo calls its concept Ethanol Boosted Direct Injection (EBDI) and its intended to enable what the company calls extreme downsizing. The idea is to use a wildly smaller-displacement engine and make big power by turbocharging the bejeesus out of it about 30 psi in this caseand thereby fully exploit E85s higher, 100-plus-octane rating.

Using E85, Ricardos super V-6 makes a heady 400 hp andget this664 lb-ft of torque. That matches GMs 6.6-liter Duramax diesel V-8, although the EBDIs torque peak is higher, at 3200 rpm. Running on pure gasoline drops the output by about 100 hp. But its not as simple as adding boost. The engine internals have to be nearly as strong as those in a modern diesel, says chief engineer Luke Cruff, and just about every piece in Ricardos running prototype has been swapped out for a heftier replacement. The twin-turbo EBDI engine has a 10.5:1 compression ratio and uses two air-to-gas EGR coolers to chill the high-pressure charge, improve thermal efficiency, and to ensure theres no overfueling of the engine under high boost. An added benefit is that a spark-ignited engine such as this can meet emissions laws without the expensive exhaust after-treatment (particulate filter, SCR injection) of diesels. That, along with a lessexpensive fuel-injection systemRicardos engine injects fuel at about 2200 psi versus nearly 30,000 in dieselssaves $2000 to $3000 per engine. This particular 3.2-liter V-6 is expected to see duty in an 8000-pound, full-size, heavy-duty pickup truck (18,000-pound GVW) in as soon as three years, and

would replace the current large gasoline or turbodiesel V-8 options. View Photo Gallery

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Alternative Fuels for America

Altfuelapalooza: Are any gasoline alternatives ready for the American mainstream? August 2010 BY CSABA CSERE ILLUSTRATION BY MICHAEL DEFORGE

Instead of a wholesale switch to electric cars, with all their inherent range and charging problems, a seemingly easier way to wean ourselves off gasoline is to find alternate fuel that could be used in slightly modified internal-combustion engines. Unfortunately, there are some very real reasons never mind what conspiracy theorists might tell you about oil companies and corrupt government officialswhy most alternative fuels are not ready for prime time yet. Heres a look at the current status and near-term future outlook of the major alternatives to gasoline.

Modern turbo-diesels get about 30 percent better fuel economy than their gasoline counterparts, have gutsy low-rpm torque, and work well in vehicles with

automatics and for towing; theyre a seemingly perfect solution for the U.S. Unfortunately, diesel emissions are far dirtier than gas emissions. Removing diesels pollutants requires costly pieces of emissions equipment. Diesel also requires approximately 30,000-psi fuel-injection systems. These costs make diesels more pricey than even turbocharged, direct-injection gasoline engines, and those gas engines have the potential to achieve about two-thirds of diesels fuel-economy advantage. While diesel costs about the same as gas today, it has run as much as 30 percent higherand it is taxed at a higher rate than gas. Theres no easy fix to keep diesel prices low, relative to gas, because American refineries, in general, produce about 19.5 gallons of gasoline and 10.3 gallons of diesel from each barrel of oil. That means a gas-powered vehicle getting 20 mpg can drive about 390 miles on a barrel of oil, while a diesel, at 26 mpg, can go only 270 miles.

Since a barrel of oil doesnt go as far in a diesel car, a wholesale conversion to diesels is unlikely in America unless we suddenly figure out how to make diesel fuel from something other than petroleum. European refineries produce more diesel and less

gasoline from each barrel of oil, but making that switch would essentially require building brand-new refineries. Dont hold your breath. One approach is to transform animal fat or vegetable oil, via a transesterification process, into what is called biodiesel. The resulting fuel doesnt contain sulfur and can be used in pure form, though many vehicle manufacturers recommend that it be blended with petroleum diesel in proportions between 5 and 20 percent. Biodiesel contains about 9 percent less energy than petroleum diesel, but it has a higher cetane rating (which promotes more-efficient combustion) and better lubrication properties. Despite Americas appetite for french fries, there isnt enough used cooking oil to make very much biodiesel. In fact, it has been suggested that to replace all of our petroleum needs with biodiesel would require the planting of soybeans on all of the arable land in the United States. New approaches for making biodiesel from algae are being explored, but they are likely decades away from mass production. Until then, biodiesels limited availability and higher cost will keep it a bit player.

Another diesel alternative is synthetic diesel, made by a variety of chemical conversion processes that transform natural gas, methanol, or coal into diesel. The resulting fuel is usually sulfur-free and has a higher energy content than petroleum diesel, plus cleaner exhaust emissions. Converting natural gas to diesel fuel, also known as gas-to-liquid, makes it easier to transport because it requires no refrigeration or compression. The cost of synthetic diesel is also reasonable, although the environmental and energyindependence benefits are minimal. Converting coal to diesel creates much more carbon-dioxide emissions than simply using petroleum diesel. In fact, this is a problem, in varying degrees, with any of the synthetic-fuel processes. However, North America has plentiful natural-gas reserves, and this could be a simple way to convert it into an easy-touse motor fuel.

The use of E85, which mixes 85 percent corn-based ethanol with 15 percent gasoline, has stalled due to the fuels limited availability, high price (no thanks to our governments tariff on E85 imports), the roughly 30 percent fewer miles to the gallon it gets, and the understanding that its use provides little in

the way of carbon reduction if the energy required to grow the corn and turn it into ethanol is factored in. Brazil, a country that achieved energy independence by using home-grown ethanol, makes the fuel from sugar. Starting with corn is a much more complex and energy-intensive process. In the U.S., sugarbased ethanol would be challenging because most of our land is unsuitable for sugar production. If we could produce ethanol efficiently from easierto-grow plants, ethanol would be a good solution. Dubbed grassoline, this ethanol is produced from tall prairie grass or even algae. Several projects to develop a workable process are under way, but commercial quantities wont appear before 2020.

A more readily available alternative fuel is compressed natural gas (CNG). Converting a gasoline engine to run on the same stuff most of us use to heat our homes is an easy, low-cost approach. Natural gas is also cheap, and America has a lot of it. And natural gas contains far less carbon than gasoline. In fact, a normal engine running on CNG almost matches a plug-in hybrid for its carbondioxide emissions. The price of CNG for the energy

equivalent of a gallon of gasoline is less than a dollar (before taxes). Still, automakers are reluctant to embrace CNG because it emits some pollutants, while a hydrogen car or an electric vehicle does not. Also, since it must be compressed to 3500 psi to get enough of it into a tank to provide a decent range, CNG requires cylindrical Kevlar tanks that are heavier, more expensive, and harder to package than normal gas tanks.

Hydrogen is the holy grail of synthetic alternative fuels. Whether burned in an internal-combustion engine or used to power a fuel cell, its primary byproduct is water. And with that emitted water, you can produce more hydrogen. Of course, its not as easy as it sounds. Most commercial hydrogen produced today is made by stripping carbon atoms from natural gasa fossil fuel. The removed carbon atoms then hook up with oxygen to release carbon dioxide into the atmosphere. If you work

through the losses in the process, it would be cleaner, easier, and cheaper to simply burn natural gas in an internal-combustion engine. Hydrogen, in its gaseous or liquid form, isnt easy to store or transport. The network of pipelines that currently moves natural gas around the country is too porous to keep the tiny hydrogen molecules from escaping. In automobiles, hydrogen has to be stored in stout cylindrical tanks and compressed to between 5000 and 10,000 psi. Creating hydrogen using solar, hydroelectric, or wind power are pollution-free solutions, but solar cells, wind turbines, and hydroelectric dams arent free. Until we come up with a cheap, large-scale, and pollution-free method of generating electricity so that we can produce hydrogen from water, the widespread use of hydrogen as a fuel seems unlikely. How To: Convert Your Diesel to Run on Vegetable Oil This months featured ratcheting wrenches helped us turn our project ambulance into a mobile deep-fryer.

February 2010

We first looked at waste vegetable oil (WVO) conversions in March 2004, when we wrote about Justin Carven and his kits (www.greasecar.com). We recently bought a used 1996 Ford E-350 ambulance for a future project and decided to find out how hard it is to install a Greasecar kit. Carven counseled against trying to convert a van because its cramped engine compartment makes it ill-suited for accommodating his kits hardware (other companies make more van-friendly conversions). We went ahead anyway, as it promised to be a good way to test our sampling of ratcheting wrenches, which we found to cut down on skinned knuckles and toiling time. To make a diesel vehicle able to cope with WVO, you essentially install a parallel fuel system with hardware that is resistant to the specific corrosive qualities of vegetable oil. This system also needs to be heated to keep the oils viscosity low. Heres the basic procedure, although some applications might require extra parts or steps.

1. Install a second tank for the veggie oil. The engine will start on diesel, and once warmed up, lines from the engines cooling system provide heat to warm the WVO. (Local veg-oil mechanic Joe McEachern prefers to switch to a 205-degree engine thermostat for better heating, but the Greasecar fuel line runs inside one of the coolant lines from the tank and, therefore, wont hold up to that amount of heat.)

2. Install the switching hardware for the fuel lines. This allows you to alternate between diesel and WVO

to both run the engine and backwash the veg-oil lines with diesel to prevent them from gumming up when cold. For the Ford, we had to remove the diesel-fuel-filter assembly, which sits in the valley of the engines vee. The GearWrench Flex works well to swivel its way around the vans cramped packaging.

3. Install an aftermarket pump to move the WVO from its tank. Some vehicles, like our Ford, can use the stock fuel pump for both fuels, but McEachern tells us the factory units wont last long when pumping vegetable oil.

4. Run the WVO fuel lines from the tank to the switching hardware, including a water-separating fuel filter with a heat exchanger. Clean, warm oil is essential, so you may have to install extra heat exchangers or filters. Wherever you mount this extra hardware will probably be cramped, so, once again, the ratcheting wrenches save a lot of time normally wasted on realigning a wrench after each fraction of a turn.

5. Wire an automated controller or manual switch to manage fuel selection. Youll also want gauges for fuel pressure, WVO temp, and fuel level if the controller does not come thus equipped. Bleed the air from both fuel systems and the coolant system; test the WVO lines first with diesel fuel.