Supercharger info

3/5/2014 Supercharger Info

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Supercharging

UNDER CONSTRUCTION!!!!

1/25/08The information here is good to read if you are considering supercharging your

vehicle. We DO NOT sell Magnuson Supercharger kits. This is purely a business

decision and not related in any way to the quality or value of this product. We simply goanother direction and focus on the kits we build in house for Alfa Romeos. I have this pagehere stricktly for informational purposes.

Why supercharging? Because supercharging is the best way to get a big increase in

power. The days of being able to increase compression add a set of headers and bolt on a 4 barrel carb to get a big increase in power are over. That worked very well at one time.However modern cars already have high compression, pretty good exhaust manifolds,aggressive cams, and very effective fuel injection systems. There is very little room forimprovement with conventional mods on a car that needs to be streetable.

A modern Roots supercharger will add 30%-65% more horsepower throughout the RPMrange. Conventional modifications can't come anywhere close. Lets compare compare realnumbers. For example I will use a 2003 Chevrolet Silverado Pickup.

Start with a K&N intake, (I will use Summit's prices rounded to the nearest dollar) it's $300,part number KNN-57-3038. Next we will need headers. Borla's stuff is OEM quality and provento work well, their headers are $768 part number BOR-17110. Add Borla's excellent dualexhaust for $836 part number BOR 14940. Next you will need a performance tuner, let's useCrane's Power Max tuner, part number CRN-1202-003, it's $430. All this adds up to $2,334.Of course I could have skimped a little here and there, but a lot of the cheaper products

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actually cause a loss of horsepower. K&N, Borla, and Crane's products are not the cheapestbut they are quality brands proven to perform.

There won't be any horsepower guarantees with these products but I figure best case youwill have about a 40 horsepower gain with this combination, most of this increase would onlybe at very high RPM where you don't spend a lot of time.

Now lets compare this to a Supercharger kit. This kit can be found as low as $3495. A2003 6 liter Silverado puts out 345 horsepower stock. The least any Supercharger kit will give

you is a 30% increase in horsepower. That means at least 449 horsepower for a gain of 104horsepower. Plus unlike the conventional modifications, the supercharged engine will providea great increase in power from right off idle all the way up to redline.

The conventional modifications cost about $58 per horsepower, the supercharger kit'shorsepower cost under $34 per horsepower. The supercharger kit provides far more power,especially down in the low and mid range area where you can really use it. Keep in mind, I amprobably understating the gains with the supercharger kit and overstating them for theconventional modifications.

Ok, so supercharging gives more power and more power per dollar, but... Why buy aMagnuson supercharger kit? There are many other brands, Vortech, ATI, etc. Some claim

even higher power gains. Warning! This next section is quite long. It takes a lot of text toexplain this properly. It's also important to remember that this entire discussion is in thecontext of the engines we deal with. There are some generalizations that don't apply to twostrokes, Diesels, Nitromethane burning dunebuggys, etc.

To explain this I first need to explain the various methods of supercharging. All methods ofsupercharging do basically the same thing. They force more air into the motor then it couldinhale by itself. This allows the engine to burn more fuel at full throttle and thus make morehorsepower. However just how more air is forced in varies quite a bit. The following methodsof supercharging are commonly used.

1. The Roots supercharger. This is a belt driven pump which has intermeshing lobes whichforce air into the motor. The Magnuson Supercharger is a modern version of the Rootssupercharger. It has various improvements to make it more effiecient. These improvementsinclude three intermeshing lobes per rotor instead of two, and the rotors are twisted 60degrees to form a helix. The port geometry is also greatly improved over traditional Rootssupercharger. Magnuson is the primary manufacturer of modern Roots supercharger kits.

Pictured Below is a modern Roots Supercharger. Over 300,000 factory vehicles rolloff the assembly lines each year with this type of supercharger.



2. Lysholm Screw Type supercharger. This type of supercharger is very similar to the Rootstype. Instead of intermeshing lobes it has big intermeshing screws. Externally it looks just like aRoots supercharger. It has some advantages and some disadvantages when compared to themodern Roots supercharger which I will be discussing. A few companies use this type,including Whipple, Autorotor, IHI, and some others.

3. The Turbocharger. The Turbocharger, often called a Turbo and originally called aTurbosupercharger is an exhaust driven compressor. It uses exhaust energy to spin acompressor to incredibly high RPM (about 2000 revolutions per second!) which forces air intothe motor. It's compressor section looks nothing like a Roots or Lysholm unit, it's more like acentrifugal fan in a modern hair dryer. Garret and IHI are the most common turbochargermanufacturers.

A Turbocharger

4. The Centrifugal supercharger. This is sort of a hybrid device. It uses a centrifugalcompressor almost exactly like a turbocharger, however it's driven by a belt not exhaust.Centrifugal supercharger kit makers include Vortech, ATI, Powerdyne and a few others. Quitea few companies make centrifugal superchargers, including, Vortech, Powerdyne, ATI, Rotrex,Paxton, and more.

Each of these systems offers some advantage over the other. Each has its srtong pointsand it's weak points. Here they are:

Roots: OK, we are talking about the MODERN Roots supercharger. A lot of vendors of othertypes like to compare using efficiency numbers from ancient GMC blowers. The modern Rootssupercharger has a few big advantages. First it's the only style that compresses the air outsidethe unit itself. This means that when its bypass valve is open (standard equipment on allMagnuson kits) it's basically shut off. This means that any adverse effects on fuel economy oremissions during normal driving are negligible. Second, below 10 pounds of boost itsefficiency numbers (i.e. power required to drive the supercharger itself and the discharge air



temperatures) are really tough to beat. Third is reliability. The Magnuson superchargerrequires almost zero maintenance. It only needs an oil change once every 100,000 miles andthat's it! It has it's own reservoir so it doesn't heat up the engine oil. Fourth and perhaps mostimportant is power. The Roots type supercharger puts out a lot of power at ALL RPM. Right offidle an engine with a Roots supercharger will typically have nearly full boost and massivepower. This power increase will be fairly constant throughout the RPM range.

Lysholm: The Lysholm unit is very comparable to the Roots in most ways. It provides full

boost from low RPM. Above 10 pounds of boost it's more efficient then the Roots blower,meaning it has lower discharge temperatures and uses less power to drive it. From a purehorsepower standpoint, above 10 pounds of boost the Lysholm is superior. From an "I actuallyplan to drive this car on the street point of view" it's not quite as good. The Lysholm has a fewweaknesses. First, most street supercharger kits run 8 pounds of boost or less so unless youare talking about a custom built motor with low compression pistons, or you are willing to burnracing fuel, the Lysholm's high boost advantages are lost. The second weakness is that itcompresses air internally. That means that a bypass valve can not fully shut it off. The result isyour engine burns extra fuel to drive the supercharger at all times, even if you don't need thepower. This also means that the supercharger is heating things up all the time which can resultin a heat soaked intercooler, totally defeating the lower discharge temps. The fact that it can'tbe shut off with a bypass valve is the main reason the Lysholm design is not the design ofchoice among major auto manufacturers. It's worth noting that some attempts at shutting it offwith an electronic clutch have been made, none have been successful in aftermarketapplications.

The Turbocharger: Turbochargers, correctly called turbo superchargers are exhaust drivensuperchargers. I think the turbocharger is the most misunderstood form of forced induction.They are often assumed to have advantages in efficiency they just don't have, and strangelythey are rarely credited for the advantages they do have.

The turbo charger has one big advantage over all belt driven superchargers. Do you knowwhat it is? I'll bet you don't because it's almost never mentioned. It's the ability to vary its RPMindependently of engine speed. This enables it to maintain its target boost levels under a widevariety of conditions. For example on a day with low atmospheric pressure a belt drivensupercharger will put out a little less boost then on a normal day. The Turbocharger willmaintain normal boost by spinning a little faster. At high altitude the Turbo can maintain normalboost levels automatically where a belt driven unit would need a pulley change to maintainboost. (This advantage is entirely negated in the United States because at high altitude 93octane fuel in not available requiring the use of lower boost anyway. If the turbo runs sea levelboost at altitude the igntion computer will just retard timing to control detonation thus reducingpower.)

The second advantage is that the Turbocharger's centrifugal compressor is very efficient athigh rpm and high boost levels. In an apples to apples comparison on an engine with 20pounds of boost a turbocharger will give more horsepower then any other form of forcedinduction. However, the reality is that most street supercharger and turbo kits are limited toabout 5-8 pounds of boost do to engine and driveline limitations. Down at these real worldboost levels the turbo's compressor advantages are lost.



The turbocharger has a number of drawbacks. At lower boost levels it's not that efficient. Infact under 8 pounds of boost it generally cost more to drive a turbo due to exhuastbackpressure then it does to drive a Roots supercharger. Yes, it's true, the story that aturbocharger is driven from "free" or "wasted" energy is a total Myth. Exhaust backpressurecost power just like a belt does. The turbochargers drawbacks are many. First of all, there islag. This problem has been greatly reduced but it's still there. Next there is the lack of powerdown at low rpm. Until the engine is putting out enough exhuast to spin up the turbo, it's notgoing to deliver much boost. Next is reliablility. The turbocharger uses engine oil which it heatsup. The extra exhaust back pressure is very hard on the exhaust valve guides often leading toaccelerated wear. Turbos have improved greatly over the years, but I have yet to drive one thatdoesn't have some lag and isn't weak below 2500 RPM. Combine that with the shorter enginelife ( do you know of an aftermarket Turbo kit that offers a powertrain warranty? No you don't )and the fact that at streetable boost levels there is no performance gain and it's hard to makea good argument for a turbo kit.

Centrifugal Superchargers: Let's get one thing straight. NOBODY has built a factory

supercharged car using one of these things since 1964, and every company I know of that didit back then is now out of business. Why is that? Because while the centrifugal units are greatfor certain applications they are poor performers on street cars. Here is the main problem. Aswith any centrifugal pump, output increases exponentially with speed measured in RPM. Inother words when set up for 8 pounds of boost (about all you can run safely on a modern motorwith pump gas) on an engine with a 6000 RPM redline they will only provide 2.8 pounds ofboost at 3000 RPM. Now for some real math. With 8 pounds of boost at 6000 RPM an enginewill gain about 54% more power. With 2.8 pounds the power gain will be only 19% at 3000RPM. Obviously below 3000 rpm the power gains would be insignificant. Take a look at yourtach when driving on the street and see where you are really operating the motor. It's rarely inthe range where the Centrifugal will be giving a lot of boost. With the same 8 pounds of boostall the other types would be giving the nearly the full 54% increase through the whole RPMrange. The Centrifugal units do have some advantages. First they cost less power to drive thenall other belt driven types. They also have lower discharge temps. This means that at 6000RPM with 8 pounds of boost and everything else equal they will put out slightly morehorsepower. The problem is that in a race by the time they reach 6000 RPM the cars withRoots, Lysholms, or Turbos will be long gone. The other big advantage is that it's A LOTeasier to make a kit using a centrifugal unit. I know, I make custom supercharger kits! Theyhave lots of fittings for easy remote mounting and they have round intake and discharge portswhich are easy to attach tubing too. With Roots or Lysholms there is A LOT more stuff to bemanufactured. The commercial success of Centrifugal superchargers is due to two factors. It'sa lot easier to make the kits, and they can advertize a higher peak horsepower number whichis all the uneducated buyer looks at. The reality is the lack of power througout the RPM rangemeans you get beat by every other supercharged car on the road.

Now I may seem a bit negative about the Centrifugal units and I don't really mean to be. Forcertain applications they are great. For example if you are building a 2000 horsepower car setup for drag racing with closely spaced gears they just might be the way to go. This is becausethe car will be traction limited at the low and mid range end of low gear so the lack of boost isnot a factor. Once the car gets going the closely spaced gears enable the motor to stay right inthe range where it makes power. If you are going to set a car up this way the ATI Procharger isprobably the way to go. The car will make more power then any other belt driven system and



not have the spooling up issues of a turbocharger.

In Summary here are the advantage of the Roots supercharger

VS Lysholm the Roots offers better fuel economy and better performance at the boost levelsyou are likely to use. Plus it offers reliability proven in over 300,000 factory applications a year.

VS Turbos the Roots offers more power under the curve and probably more power periodbelow 8 pounds of boost. The Roots supercharger has no lag, and a lot more power at lowRPM. The Roots also has the edge in reliability. As I said, try and find an aftermarket Turbo kitwith a 3 year warranty, or any powertrain warranty at all!

VS Centrifugals. This one is easy, A lot more power under the curve (that means throughoutthe RPM range) and proven reliability.

For a street car the Roots supercharger is simply the best way to go. I am sure there aresome who will disagree but consider that G.M., Ford, Mercedes, Aston Martin, Mini and otherscame to the same conclusion as a result of their own reasearch.

Shown below is the Pontiac GTO LS1 polished kit.



The GTO kit is really a top quality kit. It's expensive, but when you consider it comes with aliquid to air intercooler, all new fuel injectors, fuel rails, a flash reprogamer and more it's apretty good deal. It adds A LOT of power. Magnuson's official conservative line is that it adds110hp and 120 ft. lbs. of torque. Gains can be much greater with little work. Hot Rod magazinegot one of these cars from 280 horsepower at the wheels up to 464 with this supercharger kit,Borla's excellent Cat back exhaust system and minor tuning! Keep in mind this is while stayingemissions legal and keeping the warranty!

Shown below is the NON Intercooled polished kit for various G.M. trucks and SUVs.

This kit in Silver finish is one of the best deals in the performance world.

Here is Magnuson's description of this kit:

"This non-intercooled supercharger system utilizes the 5th Generation Magna Charger MP112supercharger with internal bypass valve. Torque and horsepower increases are improved from1500 rpm to 5500 rpm, giving a considerable increase in “power under the curve” for greatlyimproved passing power and decreased 0-60 times.

Systems are complete with all components necessary for installation. Included in the kit is thepatented equal length runner intake manifold, (replacing the factory nylon manifold) tensionerassembly, intake manifold gaskets, and all necessary hardware to complete the entireinstallation.



Other components include new fuel injectors, fuel rails, factory “push lock connectors” andregulator adapter. Computer programmer communicates with the factory ECU for propercalibration the of the supercharger system. Transmission shift points, line pressures andconverter strategies are optimized for use with the increase in torque and horsepower."

I will add that I really like this kit. It's a lot less complex and less expensive then the intercooledkits yet provides a lot of performance. The 5th Generation supercharger used in the kit isprobably the best Roots supercharger ever made. It's adds a lot of power right off idle all theway up to redline, yet doesn't have any significant effect on fuel economy. It's also superreliable. The only maintenance it needs is an oil change every 100,000 miles!

Pictured below is an installed Mustang GT Magnacharger kit. This adds up to 125hp

and up to 125lbs of Torque.

Note: These Magnuson kits are set up very conservatively from a boost and tuning

standpoint. They can deliver A LOT more power. I suggest a smaller pulley, a GOOD

water injection system (I suggest the Coolingmist brand) and tuning on a chassis

dyno.

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