hi guys, i'm toying with the idea of fitting (or rather creating) a tuned up performance head on my 2.4. obviously such a head is'nt avalible "off the shelf" so i'll have to do it myself. the head i had in mind would be gasflowed on both ports, matched to the manifolds, use fast road cams and possibly bigger injectors with a gasflowed thottle body.

now anyone who has gasflowed a head before will know that it can take a while to achive the finish you desire (some expert books sugest up to 1 hour on a single port!!) so, because i use my car regually, i thought about sourcing a cylinder head and working on it when i can buying the parts i need as i go along and fitting it all ready in one go.

so heres my questions..... there are'nt many 2.4 cylinder heads about but i have seen plenty of coupe 20v ones so the first thing i need to know is can i use a 2.0 turbo/non turbo head on my stillo block? is there a difference between the turbo and non turbo versions, also are there any performance gains from using a turbo aluimum manifold over my plastic variable one? and if i fit bigger injectors and a performance cam, will it mess with the fueling and run lumpy?

Hi Gadge,

Not sure if anyone has done what you are looking at doing to a 2.4 head but i would be thinking about contacting Guy Croft engines for advice. the Coupe lumps were 2 litre so i don't know if the bores are the same and the strokes differ. i would have thought that you could get a head quite easily from a scrappie.

hi martin, yeah the scappie idea is a thought, we only have one local one in rugby and i can't imagine they'ld have a stilo abarth often, i was more thinking ebay? i have a sneeky feeling that the heads are all the same across the range of 2.0 non turbos right though to the 2.4 and i even think the bore is the same as the 2.0 its just the stroke that is different. just need a definate answer. i also need to know if the turbo head is a better head to fit over the non turbo one?

sorted, found someone who will sell one from a stilo with the exhaust manifold for £150........ dunno wether to bite the bullit or not??

Gadge I'm sure you'll do what you feel's right. But personal view I would not think the benefit of: cost of new head; the labour for gas flowing; the hassle of head removal and refitting will produce comensurate gains. I'm guessing plus four or five HP at best.

Are you really that unhappy with your car's current performance?

Not the best engine to tune due to being a bit fragile I've heard, but the Brazilian guys seem to manage quite well.

http://forum.octanestyling.com/sutra67363.php&sid=dde302083e0ae1a6c97d049991ad9982

Its only fragile if you have Oil pressure problems causing crank float. Keep the oil neither under or over and it is fine.

silly question. 2.4 jtd engine. Does it use the same block ie bore and stroke as the stilo. And how similar is the engine to the one used in the focus st and volvo's.

Yellow Peril said:

Gadge I'm sure you'll do what you feel's right. But personal view I would not think the benefit of: cost of new head; the labour for gas flowing; the hassle of head removal and refitting will produce comensurate gains. I'm guessing plus four or five HP at best.

Are you really that unhappy with your car's current performance?

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not so much unhappy, think of it as an engineering exercise? i'm allways thinking of ways to make the car perform "better", and as some are aware, cylinder heads are manufactured to a budget, and so are made very good to do the job, but could be alot better if you want to achive really good gas/air flow (more unrestricted air/fuel that flows in, the better the combustion etc, etc) and with a bit of time (which cost me nothing) i could get this by grinding and polishing and making sure every burr, casting join and passage that air flows through, is smooth and free from restrictions......... but your right peril, it totally is'nt worth doing just the ports as like you say the benifits would'nt be worth it so i'm also going to add fast road cams, and possibly bigger injectors too . i'm a tinkerer at the end of the day so i just can't help myself!

and as for the strength of the engine? well, research sugests that theres no reason it would'nt cope? i mean, 600bhp has been squeezed out of its smaller turbocharged brother, and i've heard the stilo crank is pretty strong too?

but this is just the sort of discussion i'm after so please keep your views comming in, i'm really interested in what everyone thinks and if theres anyone who has any tips or advice?

gadgemyster said:

and as for the strength of the engine? well, research sugests that theres no reason it would'nt cope? i mean, 600bhp has been squeezed out of its smaller turbocharged brother, and i've heard the stilo crank is pretty strong too?

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I like your style. That'll be one in the eye for the "2.4 engine's are made of rice paper" brigade!

gadgemyster said:

and as for the strength of the engine? well, research sugests that theres no reason it would'nt cope? i mean, 600bhp has been squeezed out of its smaller turbocharged brother, and i've heard the stilo crank is pretty strong too?

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Its turbo charged little brother is good for 300 at the wheels after that the crank, con rods, pistons have to be replaced with forged parts or more heavy duty parts from other vehicles VW etc..

The same applies to the 2.4, 300 at the wheels is an absolute max the standard parts can cope with. Most replace crank, pistons etc. well before the 300 mark is reached.

600 from a standard 2.4 crank, no chance IMO.

some quotes from another forum


don't mess with the combustion chamber unless you have the ability to cc them afterwards otherwise each cylinder is going to be running a different compression causing an imbalance due to secondary harmonics introduced from the combustion cycle.

many people think headwork isn't worth the effort. As there are major losses low down and in the midrange to only be complimented by small gains at the top

you should be looking at the cam profile that is going to be run and adapt the design to maximize flow for the cam lift and duration in question to ensure low down throttle response midrange gains and top end.

oh yeah i see your point there shady, at the moment, i'm looking for around 220 - 225bhp, on standard equipment except camshafts. i think thats do-able. if it gets to around 300, i don't think it would be as smooth and drivable at low speeds?

dave said:

some quotes from another forum


don't mess with the combustion chamber unless you have the ability to cc them afterwards otherwise each cylinder is going to be running a different compression causing an imbalance due to secondary harmonics introduced from the combustion cycle.

many people think headwork isn't worth the effort. As there are major losses low down and in the midrange to only be complimented by small gains at the top

you should be looking at the cam profile that is going to be run and adapt the design to maximize flow for the cam lift and duration in question to ensure low down throttle response midrange gains and top end.

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thats good stuff dave, i did'nt really think about the putting the combustion chambers out of balance?

gadgemyster said:

oh yeah i see your point there shady, at the moment, i'm looking for around 220 - 225bhp, on standard equipment except camshafts. i think thats do-able. if it gets to around 300, i don't think it would be as smooth and drivable at low speeds?

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I believe 200 can be achieved quite easily with bolt on induction and exhaust upgrades plus a remap.

I see no reason why a properly tuned head with reprofiled cams shouldn't give you an extra 20 to 25 bhp.

gadgemyster said:

thats good stuff dave, i did'nt really think about the putting the combustion chambers out of balance?

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i'd have a good read around some other forums where people are more into tuning, there are a lot of people out there doing head work, but it seems very few that actually can do it right

Shadeyman said:

I believe 200 can be achieved quite easily with bolt on induction and exhaust upgrades plus a remap.

I see no reason why a properly tuned head with reprofiled cams shouldn't give you an extra 20 to 25 bhp.

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thats the figure i'm aiming for, i always thought that this should be what is should've had and would'nt be interested in going any further

dave said:

i'd have a good read around some other forums where people are more into tuning, there are a lot of people out there doing head work, but it seems very few that actually can do it right

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yeah i've been hunting around the coupe forums and on here for quite a few weeks before i started this thread just to see if it was possible to do to a 2.4, its always the case that some people have all the best intentions in the world of improving the gas flow but end up do little or no difference at all? luckilly i have plenty of time on my hands and a great forum for info and advice

i mean other non fiat forums

I think all of these power gains that forums show for simple mods are a load of horse crap.

I have actually been working with somebody with similar ideas, using coupe manifold, cams and head work etc etc. I dont know their exact plans for this engine nor can i claim to understand it all even if i did but i understand that you will be very lucky to see over 200bhp in real figures.
It will cost a lot of money but a REAL 30bhp will make the car lovely if the figures dont steal torque, work under 4k revs and dont require high octane fuel. Thats our aim any way.

Edit:- None of our plans involve an Induction kit either.

i used to have a Honda Integra Type R. It made a dyno proven 187hp as stock. I put a decat and catback exhaust on and it made 197hp. I then put a 4-1 manifold and dastek fuel computer on and it made 211hp.

it might pay to look at doing a cat removal pipe or sports cat on and a remappable fuel computer. I also have them on my bikes and with a less restrictive exhaust and computer you can get 10% gains.