Fiat FIRE Engine Upgrade : 1.1 8v to 1.4 16vThe fiat FIRE Engine first appeared in the early '80s as an 8 valve 1.1 litre, lively, rugged and quite a lightweight unit but has been extensively developed and is still in use in new cars today. Being essentially the same engine as the 1.1 it becomes a fairly easy job to upgrade to a 1.4 16v and increase power from 54 to 95 bhp.

The 1.4 engine can be taken much further than this but the aim of this conversion is to gain a huge increase in performance with little or no cost.

The starting point was finding a suitable donor for the engine; rather than buying an engine it makesmore sense to start with a complete car so that you know the engine is sound and is complete with loom and ECU. My donor car was a 2004 Fiat Stilo costing £200 (cheap due to no MOT and no clutch).

Fiat Stilo, with wheels removed ready for engine extraction.

After a couple of hours the engine was out of the car but I spent the rest of the day stripping other items from the car. For one I wanted to keep as much of the wiring loom as possible with the electronic throttle pedal to give me the option of re-using this in the buggy. I also stripped many other parts for selling on eBay, which earned me around £100 and halving the cost so far.

The 1.4 16v FIRE engine, with mountings, aircon pump etc.

After cleaning the engine the next job was to extract the old engine from the buggy. The easiest wayis the jack the buggy up out of the way whilst dropping the engine to the ground. Another simple job, being able to work the engine free of drive shafts.

The old engine hits the deck.

With the two engines side by side I set about transferring components. I had already removed the gearbox from the 1.4 engine as the clutch needed replacing and I wanted to use the original five speed box from the buggy as it's a smaller unit and the ratios were perfect.

I would also need to transfer the alternator as the 1.4 unit is mounted on a block which holds the aircon pump all of which is unwanted extra weight and bulk.

The two engines, same block but looking very different.

The original Seicento engine mounting bolts directly to the block without a problem but the alternator and crank pulley was not quite as simple.

The Stilo has a larger and heavier pulley with the sensor ring and pulley the opposite way round from the Seicento which would have meant the alternator position would have need spacing so far out that it would foul the mounting. I transferred the pulley off the 1.1 engine to mount the alternator further back although it still needed spacing off by 5mm (3 washers).

Original alternator on 1.4 block.

The crank sensor needed moving out by 18mm to align it with the Seicento pulley and for this I made an adaptor to mount on the original sensor mounting point. The adaptor is a tight fit but I also used a strip of aluminium from the new bolt hole to the original one in the casting just to make sure the adaptor doesn't work loose.

Sensor adaptor design and in situ.

The next job was the deal with the clutch and gearbox. I had the choice of using the original clutch from the 1.1 engine and change the flywheel or buy a new one to suite the Stilo flywheel. Since the buggy weighs only around 500kg I decided the lighter clutch off the 1.1 would be better suited and this also saved me the cost of a new clutch.

Clutch and flywheel from 1.1 and 1.4.

The 1.4 engine with 5 speed box from the 1.1.

For wiring up the engine used a good set of diagrams from a CD based manual off eBay which covered all the Seicento but for the Stilo it took more searching before finding another CD image for download. I have since found all this available on the Fiat Forum web site.

The Stilo engine loom is separated form thecar by two large connectors. The D4connector was retained and many of theunused connectors were reused to route allwring via this connector to the originalSeicento wiring. All connections were madewith the engine on the floor until the enginewas running as it's easier to access all therequired wiring that way.

Connector blocks were used initially until Ihad all the required connections for theengine to run. A few mistakes were madebefore the engine finally ran partly due tosome dubious wire colours with some brown,and orange wires looking a more beige and alittle ambiguous.

The battery had to be moved out of the buggynext to the engine as using long wires toconnect to the battery was losing too muchpower.

All electrical connections made, the engines runs.

I had planned to get the ECU modified to disable the immobiliser but tried three different companies who did this kind of work and none of them were able to do it. So to get the engine running I had to use the Stilo immobiliser circuit.

The immobiliser, with original Stilo key next the the sensor.

I mounted the immobiliser circuit in a new waterproof enclosure, stripping out all unused connections. An additional relay is required to power the injectors and lambda sensors as the Seicento has only one to do both. (The Stilo switches off the fuel pump at pressure.) This additional relay and fuse will be housed in the same enclosure.

The earth connectors on the rear. Power connections on the left, sensor and CAN on the right.

The immobiliser requires connections on 2 plugs (A and C) plus 2 connections via F for which there is no plug as this is the connector to the fuse box.

Connector A has 2 wires to connect to earth (N). Connector C has two CAN wires (SN, SB) and HBto connect to the engine loom. There is also the two wires to the key sensor (BM, BH).

The two extra connections on socket F are:-

Pin 9 : To ignition supply (CN)

Pin 18 : To permanent supply on Stilo but routed to IGN supply.

Permanent supply presumably needed for Stilo remote locking or alarm but as we are only intereted in the immobiliser circuit it can be routed to the ignition supply instead to prevent power drain fromthe battery.

The immobiliser is coded to the original key from the Stilo and so as this would be needed to start the car I decided to do away with the Seicento key and convert to a push button start.

The Stilo key. Ignition switch and starter replacing Seicento key.

The immobiliser key sensor ring was removed from the ignition barrel and is now hidden behind thenew key slot.

Both the ignition switch and the starter button should be able to run enough current but it was easierto leave all the heavy duty wiring in place and put in a couple of relays where the ignition barrel used to be so these switched are just running low current to the relay coils.

The engine installed and running with air intake and exhaust from the 1.1 engine. The only other modifications required were to install the electronic throttle and a slight re-routing of the cooling system as the lower water pipe is on the other side of the exhaust manifold.

The buggy now runs with the new engine with the only problem remaining being the engine management light being permanently lit with an ABS fault showing. There is of course no ABS so the plan is to find a way to fake the ABS signals to the ECU. Alternatively I learn to live with the warning light on permanently as I have with the airbag and power steering warning lights.