The Fiat F.I.R.E engine and my experience with tuning it

Right, Modified Monsters is getting a fair few members with a passion for there little Fiat powered by the fantastic yet simple and cheap .f.i.r.e engines so here is my guide to the little bundle off joy from my own experience! (Aimed mainly at the cinquecento here)

Im going to be a little rude here and skip the 1108.....its a fantastic engine and it does its job very very well but when it comes to making your Fiat fast, sense will make you go for the 1242 range right from the word go, the reason for this is its so so simple to drop and 1108 out and fit in the 1242 60 or 75 engine.
The 60 engine looks identical to the 1108 and surprisingly it can be run sweet as a nut off the 1108cc spi ECU ecu, the 6hp gain isnt really going to put you with the big boys but wait its more than that....the 60 has a longer stroke and is designed more around a flat torque curve than power and revs so things like bolting on a turbo complements this really well.
The 75 engine however is the one to go for if your going down the high boost turbo route and ill discuss this later.

Things to no about the 1242 60 and 75 engine.......

they have always suffered with premature head gasket failure which makes people think they aernt reliable......is this true??....NO! -
A good way to ensure a solid reliable head arrangement is to whip the head off and ensure the block and the head are clean and perfectly flat! next use a good quality head gasket set, this is the hidden trick here. A set from the likes off Payen will be the best move and to make sure the gasket can do its job without issues always change the thermostat, on a turbo its better to run a cooler running item like an 83 degree stat....this is because temperatures in the head over time can lead to the head misshaping and warping leading to gasket failure and the engine doesn't have to overheat for this to this to take place (its more down to the head and cooling design)
You will find a thermostat to suit in Halfords listed for a Renault 5 GT turbo, and if you are struggling to find one then look at the ones which look the same and then look for the temp reading on the top

Right...next, f.i.r.e engines suffer from wear on the skirts off the piston leading to piston slap which sounds like a spoon on the side off the engine when idling, once you hear this its to late and although the engine will normally be fine its time for a new one, to help prevent this however its simple -

1. Dont use cheap cheap oils.....yes the f.i.r.e engines where only designed to run on 15w/40 mineral oil but oil technology has moved on alot and Fiat never designed your engine to go to the moon and back let alone run a turbo so use semi/fully synthetic oils that aernt to thin! anything under 5w/40 will be to thin and will make the engine noisy. This is because the engines are old and tolerances are large compare to todays 0w/30 engines etc.
I recommend 10w/40 semi syn and even better to use a classic thick treatment such as the Wynns oil treatment and this will work a treat....quiet, smooth and the best protection against wear!
And finaly all the f.i.r.e engine range suffer from leaking rear main core plugs and they tend to allow antifreeze to contaminate the clutch leading to clutch slip on turbo engines, so always replace them when doing a clutch....its a simple job to remove the flywheel while your in that area and the core plug is pennys from Fiat, you have been warned! mine started leaking after id had the gearbox off to replace the clutch and flywheel and for the sake off a couple off pounds i didnt bother....and being a turbo car the gearbox is alot harder to get to than normal....doh!

My experience with tuning the 60 and 75 engine with a turbo!

Low boost – want economy, drivability and reliability?? –

The 1242 60 engine is the ideal candidtate when it comes to low boost because its cost effective and the proven “second injector” method works best on the SPI wet manifold over the 75’s dry maniofld so there can be fueling issues there. The goal with low boost is to run no more than 0.3-0.4 bar off boost so that the stock internals and compression ratio aswell as fuel pump can be manitained, this involvoes using a second injector such as the tried and tested Bosh 803 green injector from the Sierra RS Cosworth which can be bought from Burton power with the securing clip for the top of the injector for £85.
To control the injector for on boost fueling you need an injecotor driver such as the ERL Aquamist MF2 which origonaly was a water injection controller but it can and does control one or 4 injecotrs very well in a basic way. Other units are available for a cost but as with most things you get what you pay for so the more exspensive injecotor drivers/fueling computors will do the job better.

Now the turbo.......

Being a low boost its never going to be a subaru so its best to concentrate on drivability, A Garrett GT15 or T15454 (or simaler sized turbo from the likes off IHI) turbo will work perffectly at 0.35bar with rapid spool up, its cheap and easy to find on early VW TDI engines and astra turbo diesles off old.
Here is an example off my first low-boost setup ands the results –

Garrett GT15 turbo (0.35 ex a/r)(0.33 cp a/r)
ERL Aquamist MF2
Bosh 803 second injecotor
Fuel Cut Defender
Dump valve
Decat stainless exhaust
Cone filter
40mm throttle body

96.6bhp @ 6600rpm/96.6 lb/sf of torque

This makes for a nippy and reliable engine with good economy when driven nicely, its also cheap to put together (compared to high boost) but it has limitations which i learnt the heard way on my own car! –

Vanaakens high boost cinqs proved to be a little bit prone to blowing up!, this was because there is no protection on the 1108/1242 8v engines against detanation and once the boost is raised above 0.5bar this can be an big issue. One off the main reasons why these kits where prone to det is because off the fuleing and inlet manifold arrangement, the SPI manifold tends to make cylindres 2 and 3 run rich and 1 and 4 leane.....this isnt a problem at lower boost levels but at the higher levels it becomes an issue and again with no failsafes its asking for trouble!, there is also the slight issue that every turbo cinq that has suffered det to the exstent where a piston has been holed its always on number 1.
The suspected reason for this is due to poor cooling at this cylinder around the head leading to a hotter cylinder and even hot spots within. So for saftey and reliablility i would strongly advise moving to the 75 engine for high boost, there is also the slight issue off the Servo take off on the 1108, and the 1242 8v spi manifold which is placed on the inlet track off cylinder one which causes problems with fuel entering the pipe under boost and causing slight varyations on the fueling on that cylinder.

On the subject off SPI turbo setups having fueling issues.....

Here is an example off one off my setups that caused a huge head ache, here is the spec list i ran for a high boost spi setup –

GT15 turbo, 3 bar fuel pump, adjustable pressure reg, decat 2” exhaust system, MF2 and cossy injector, ported head with three angled valve seats, 75 cam, adjustable cam pulley, 1.5mm decompression plate.

This setup was intended to take me to 130ish bhp running 15psi off boost but when i actaully had it setup it was bad news, at 10psi it was pinking and simply wouldnt run the desired boost so it left me with a respectable 116bhp/113lb/sf torque. The reason for this was clear.....my head was skimmed to much so my compression ratio was higher than it should be and the SPI setup was highlighting this issue by giving me a very low tolerance for det with a lean running cyinder one and four, with correctly disstributed fuel i would have got away with running more boost and therefore would have made more power on the higher compression ratio, so not having any money and stupidly seeking more power i went home and added another headgasket to sandwhich the decomp plate lowering the c/r by a further 1:1, this gave me an estimated 7.5:1c/r.
I then returned to the rollers to try and run my disired 15psi off boost and was shocked to see that running the same 10psi as before id lost 22bhp! Adjusting the cam timing gained me another 5bhp leaving me with a total loss off 17bhp from lowering the c/r this much! So i was now running 99bhp.....not much more than the low boost setup a ran before, they began to increase the boost to 0.8bar where it made a low 112bhp, then to 1 bar (15psi) where it only scrapped another 6bhp giving me 118bhp, this was most dissapointing but the only plus side was running the little T15 at this level off boost gave an inmpressive torque spike low down giving me 126lb/sf of torque.
On the road this felt out and out rapid and althought the setup was seriously floored it worked well and it stayed this way for some time other than some exhaust modifications and intercooler mods which i estaimated to bump up the power too 125bhp. The reason why the setup wasnt working to well in terms off power was a number off factors –

1. The small T15 turbo was now running a boost level it wasnt designed to do causing it to over speed and superheat the air exiting the turbo giving the small intercooler one hell off a job (air after the cooler reached 65degrees in winter) so the increase in boost meant an increase in power was minimal at best on the unefficient engine setup.
2. The now very low c/r had made the engine very unefficient and made the job off the turbo very hard.
3. And again the fueling was very poor with the outer two cylinders running far to lean and the inner two far to rich.

So there you have it.....the way not to do it! If you dicide to go high boost on the SPI setup then to ensure a more reliable setup its wise to aim for 8.5:1 compression ratio and run high octane fuel such as 97ron, and combine this with a good intercooler...but above all stick to 0.8 bar and try and make the engine flow well with a good exhaust, throttle body and a free flowing inlet track for a good bhp figure.

Now the 75 engine for high boost.........

The 75 engine is the ideal candidate for running high boost, and there is a few reasons why, one is because it is an MPI engine meaning sticking with that will ensure an even 25% split off fuel for a good clean reliable burn in each cylinder with an accurate reading out the back off the car for the lambda probe while in a rolling road setup, two... because the 75 engine has under piston cooling jets which works against det keeping the crown off the piston cooler to avoid hot spots, and three the 75 engine has larger ports/valves/inlet tracks etc meaning more flow for a higher less stressed power output.
There are three ways to go to go about fueling the 75 engine for onboost fueling.
One is the least ideal but it happens to be the way mine is setup......this is because it was cost effective for me and i was fully aware off the issues and down falls off doing it.This is to run four larger injectors inplace off the stock 75 ones and allow an injector driver to control them on boost (in my case an ERL MF2) and the job of “off boost fueling” is left to the stock 1108 ecu by mounting the stock SPI TB onto the MPI manfiold!! This means you have a good even fuel distribution from the MPI when you need it most and a simple costless way off fueling the engine off boost with things such as economy and drivability being maintained. Its a “bodged” yet clever way off gaining the reliability and power of MPI for on boost fuleing while maintaining the stock ecu and although it isnt ideal its earned my turbo cinq the title off the UK’s most powerful 1.2 8v turbo 1242 75 engine (with a smart choice off turbo to boot!!). The thing to be aware off here however is the stock 30mm or 32mm 54 and 60 TB’s are a little to small for the 75 engine if your using this method let alone a turbocharged one so use something like a 40mm (enlarged stock item) TB for the best results.

The next way is a better way off doing the above and it includues the simple job off swapping the SPI loom and ecu for the 75 bits, this way the off boost fueling is now MPI. Now to fuel the engine on boost you will need to mount an additional 4 injectors on the MPI manifold like the o.e 75 injectors which will give you enough fuel for an additional 75/85bhp over stock using the standard 75 items. This is a better way off running the 75 engine efficiently off boost!

The last option is the better off the three and its basically to go for fully indapendant “standalone” managment and fit 4 larger injectors to suit your required bhp, Standalone will give you the otion to run a knock sensor for ignition retard on knock and finer adjustments to the fueling which will mean a more powerful safer engine for running boost on.
But regardless off which choice you go for you now have the option off power.....120,130plus,150plus?? These choices will now influence the choice off turbo, If you plan a simple 120bhp spec then the Garrett T15 454 turbo will do the job nicley at around 10psi (max safe pressure) with the added bonus off huge low end torque and rapid spool up for a quick road car. But to go above 130bhp you really do need to move up the scale to something like a Garrett T2 from the likes off the Ford Fiesta RS Turbo or the Renault 5 GT Turbo, the T2 is slightly larger than the T15 on the comprerssor side and unffortunatly has the same issue with boost limits so sticking to 10psi max is strongly advisable, but bolting a T2 onto the 75 engine over the T15 will see another 10-15bhp so you will now have a possible 130-135bhp on tap with a good choice off intercooler and a free flowing decatted exhaust.
It is possible with both the T15 and theT2 to run 15psi but you will gain little for the side effects like massivly shortened life off the turbo, it may be possible to see 145-150bhp on the 75 with a T2 running 15psi but i dont advise it and there are smarter turbo choices that will open up a new world to new specs!

I currently run a Garrett GT1752 turbo from a Saab 2.0l turbo which is hybrided with a GT15 centre bearing housing for ease off fitment, the GT1752 is an amazingly good choice for the 75 engine if you are aiming for 150bhp and over, it combines low lag with a wide scope off boost levels and power, the turbine housing has an area ratio off 0.47 which is large enough to ensure the best scavenge in the engine off boost (less back pressure) while flowing enough gasses for high outputs and the compressor housings area ratio is 0.53 making it rather large (larger than the Garrett T25) and is at its peak efficiency between 8 and 15psi!! Running between 140 and 200bhp with the max rating around 250bhp. A GT17 fitted to a 75 engine with a good intercooler and exhaust etc can be exspected to see 140bhp as low as 7-8psi....150-160bhp @ 10psi.....170-175bhp @ 13-14psi and as much as 180bhp @ 16psi on a well flowed engine with a good fueling setup.

An example off my restrictions on my setup on the GT1752 and wat it did for me –

Small intercooler/resrictive 1.5” throttle body plenum inlet, decompression plate over forged pistons.

With the above issues the car still made 156.6bhp and 146lb/sf of torque @ 14psi off boost which made it the most power 8v 1.2 turbo f.i.r.e in the uk to my knowledge . Realizing there was more potensial to be unlocked i looked into how to solve the issues. The first being the intercooler......struggling to fit a larger cooler i went for the option off fitting water methanol injection which unlocked around 8-10bhp giving a theoretical 165bhp and 155lbsf of torque and the difference on the road was fantastic with the increase in power making itself very known! My next step was to remove the restriction in the inlet which when done will bring the power level upto around 170-175bhp with 165lb.sf of torque but i have yet to do this and now fear for the rods and pistons!
Even with the small intercooler and restrictive inlet my car made good power at 14psi off boost! showing the capability's off the GT1752 turbo.
There are other options such as the Garrett T25 but this really doesn't suit small engines due to the fact that the exhaust housing is very large meaning massive lag and the compressor is smaller than the GT1752 meaning overall the power output will be less and the drivability alot worse!


Limitations on the f.i.r.e engine.

Bolting on a turbo to any engine will shorten its life due to the increased stress but there are levels considered to be unsafe, for example the estimated “safe limit” for 1242 8v f.i.r.e conrods is around 140lb/sf of torque....... however i have ran mine at upto 160lb/sf for several months with some aggresive driving without an issue but then i dont sit it on the rev limit in every gear under full load so the amount off abuse the rods will take is unsure to anyone im affraid. One way to ensure the rods will take more stress is to have them shot peened which eliminates surface defects which will ultimatly lead to weak points where the rod may break from and its also worth while fitting uprated Big End bolts when dealing with prolonged high revs!
The 1242 16v super f.i.r.e engine is considered to have both stronger and lighter rods and pistons than the 1242 8v engines and there is a huge plus point to fitting them to the 8v engine and thats that it lowers the compression ratio to around 8:1 without totaly messing up the fuel squash so in theroy this way you will stand a better chance off avoiding detanation and you be able to run high boost levels at the lower c/r they deliver
The next is limitation off the head bolts and big end bolts...
If you plan to make the your 1242 60/75 engine rev higher or produce its peak power alot ohigher then it would be wise to fit uprated head bolts and big end bolts full stop!
You will also find that with this small engine it will take alot of money to get it reliably over 200bhp or even to run 170bhp reliably due to the fact that you would need to think about forged internals and head work etc etc.

I will be adding to this post shortly......................... thanks

jason