Tuning Tuning a 1.2l fiat 500, "ghetto style".

[TurleysIndependantTuningS]

Unfortunately for anyone wanting to tune the intake, it's nothing like an older car at all.

Unless you are running at full throttle, modifying the intake system will make absolutely no difference to the engine's power. The airflow is constrained by the butterfly valve, and the computerised engine management system injects precisely the correct amount of fuel for optimum combustion. If the intake is more freely flowing, it just means the butterfly valve won't need to open as much. Only when the butterfly valve is fully open is there going to be any gain in absolute power, and that will in any case be minimal, since the biggest obstruction to airflow through this engine is the exhaust manifold, particularly the built-in CAT.

Except when you've got your foot to the floor, you'll see no difference at all.

Luckily i have my foot to the floor about 90% of the time

 

[TurleysIndependantTuningS]

I've never done it myself but am really considering it with my car as it's a later Euro 6 car with pretty much no bottom end grunt so anything will be an improvement, I have heard before that they just bolt straight on (not 100% sure how true it is though, I'm thinking the only way to find out is to just try it using the trial & error method) its just the internal diameter of the throttle body is a few mm bigger, on both 1.2 & 1.4 8v the air box & all that is all the same & visually they look identical whereas the 16v has a completely different setup so I'm thinking on the theory as long as it's off a 1400 8v it should in theory be plug & play, I suppose it's similar to the old cars where you stuck bigger carburetors on them, the only thing would be if the car throws up a fault if it detects something's been changed

Im probably going to get one, and try it out, i want to find a complete one though,
So i can see if i can modify the old one after i take it off.. it might be useful for making this 2 Stage intake i have been dreaming up..

 

[TurleysIndependantTuningS]

As I have said, I have been looking at a lot of options for my little 1.2 in my Punto which is the 16V 85hp engine you can uprate the whole intake system and the exhaust. port and polish, new cams and remap the ECU, even after all that which would easily run into 4 figures, you would still only get just a little over 100hp as this is what other people have done. Its been proven, tried and tested.

The 8valve head here is going to be the main limiting factor. you could add a turbo but has been proven on this forum over the last 20 years a stock 1.2 engine tends to die extremely quickly once you add a turbo. They are just not reliable.

One member on here "Brin" managed 150ish HP out of a 1.2 8V Punto a few years back (maybe 10 or more now) by fitting a turbo, but the engine just destroyed itself repeatedly and he spent a fortune on that. one other Turbo punto I know of, that was discussed recently burnt to the ground when it caught fire.

Even at 150hp that is still not as much as a stock Grande Punto Abarth, and you could get 595 Abarth and tweek the boost for instant gains.

Ok, you have successfully talked me out of the turbo or supercharger path..

Can you port the head much on these?

 

[puntodeltathema]

Surely the limiting factor here is the hopeless Marelli engine management. The more I work on cars with this system the more I despair. Random ECU faults, ridiculously over-sensitive to things like cambelt changes....is an aftermarket programmable ECU and maybe some decent injectors not the way to go? Even finding a way to transplant a Bosch system from a 16v might give you a better base.... Discuss!

 

[Danoid]

The time you’ve declared all your mods and insurance premiums go up be cheaper to buy a more powerful standard car surely?

 

[jrkitching]

Surely the limiting factor here is the hopeless Marelli engine management. The more I work on cars with this system the more I despair. Random ECU faults, ridiculously over-sensitive to things like cambelt changes....is an aftermarket programmable ECU and maybe some decent injectors not the way to go? Even finding a way to transplant a Bosch system from a 16v might give you a better base.... Discuss!

If it were that easy to get meaningfully more out of the engine without substantial hardware changes, the chip tuners would have by now made far greater gains than they have.

I think Andy's hit the nail on the head with this:

you are still always going to be limited by the flow through the much smaller cross section of the 8valve engine

This just isn't one of those engine designs that's amenable to tuning. It's a 40yr old design at least, and given the magnitude of the changes and compromises that had to be made to get peak power up to 69HP, there's not much more to be easily had.

 

[puntodeltathema]

The time you’ve declared all your mods and insurance premiums go up be cheaper to buy a more powerful standard car surely?

Well possibly but given the original problem statement it's interesting to pursue the thought experiment!

Interesting to reflect that in 1979 the Lampredi SOHC 8v engine, with a carb, inline valves and a non-crossflow head, developed 78bhp from 1301cc. I'm sure that engine could be tickled up a bit....

 

[TurleysIndependantTuningS]

The time you’ve declared all your mods and insurance premiums go up be cheaper to buy a more powerful standard car surely?

I declare nothing!!

 

[porta]

Well possibly but given the original problem statement it's interesting to pursue the thought experiment!

Interesting to reflect that in 1979 the Lampredi SOHC 8v engine, with a carb, inline valves and a non-crossflow head, developed 78bhp from 1301cc. I'm sure that engine could be tickled up a bit....

Definitely…my 128 3P with twin, twin chokes, used to go like stink…frightened an escort 2000l harrier…it had a rover ‘welded where it fit’s’ exhaust system on it and a strada higher output alternator

 

[puntodeltathema]

There's your answer then - find a 128 engine

 

[puntodeltathema]

More seriously I think the Cinq and Seicento boys have had some luck tickling up the FIRE 8v?

Probably not to 100bhp though, admittedly....

 

[TurleysIndependantTuningS]

I just think if it were as easy as bypassing the cat then you would just stick a straight pipe in and not bother with complex vacuum set ups, also if you could just slap a set of secondarys on the intake then again fiat would probably have done that at some point in the life of the 1.2 engine. even if you could get loads more air in, and out again. you are still always going to be limited by the flow through the much smaller cross section of the 8valve engine, the lower compression ratio of the 8v engine and the small displacement.

The injectors can only deliver so much fuel. The ECU is not tuned for performance it is tuned for longevity and economy.
Unless you're willing to open your wallet and let a machine shop take a couple of fists full of cash out, you'll never get a 69hp engine up to 100hp. or if you did the engine would not last long at all, and would probably not be balanced enough to cope with the RPM needed to sustain that output.

Fiat are and always have been pretty good at wringing as much power out of their engines as is practical, which is what there is not much scope to tune them further in the after market.

See, i wont de-cat it because I want it to pass a uk mot..
The plan with the bypass pipe is that it would be closed at the mot test rpm
(2k rpm) so it would pass the mot
But when its over the test rpm it opens up and goes faster.

The "two stage intake" is basically a hose fitting, an adjustable vacuum valve and some hose and a filter. Its a cheap plan but it would work!

 

[TurleysIndependantTuningS]

The time you’ve declared all your mods and insurance premiums go up be cheaper to buy a more powerful standard car surely?

I declare nothing!!

 

[TurleysIndependantTuningS]

If it were that easy to get meaningfully more out of the engine without substantial hardware changes, the chip tuners would have by now made far greater gains than they have.

I think Andy's hit the nail on the head with this:


This just isn't one of those engine designs that's amenable to tuning. It's a 40yr old design at least, and given the magnitude of the changes and compromises that had to be made to get peak power up to 69HP, there's not much more to be easily had.

Apparently a chip tuning place promised they can get me 10 hp above stock..
But possibly more if i had intake/exhaust mods.

I get you though, im just gonna experiment with it a little bit see what happens

 

[porta]

There's your answer then - find a 128 engine

It was put in the Uno, strada etc well after the 128…and at 1500cc…the fire, superfire etc etc engine USED to have an aftermarket tuning market, but, as things got more ‘electronic’/software, there was little point to the add-ons as the ‘computer said no’…that’s not to say it can’t be done, just that ‘we’ have seen little evidence of it

 

[FiatMatt94]

With mine I'm not looking for power gains, just a very mild but noticeable improvement that's all & making it breathe a little better as I'm thinking that where the problems are, mainly bottom end of the rev range upto 2,500 rpm as I've noticed under them revs is where it's worse, over 2,500 rpm it's fine, I've already installed a BMC filter element in the standard housing which has made a slight improvement but I thought of something else as well, the single silencer exhaust system itself is restrictive as from personal experience when I daily drove Classic Mini's mine had a standard single box exhaust just like the Panda's & 500's, to which I always found restrictive, I used to change them for another standard system but one with both a centre box & back box, although there were no power gains you could feel it wasn't so restricted as with a single box & drove better, so when I change the system on the Panda when it's past it, I was always planning a stainless system to standard spec as it's only a bit more money on the Panda than off the shelf pattern parts, I'll get one made up with a small centre box as well as a back box & it should make it feel a bit less restricted as it always worked with Mini's

 

[varesecrazy]

Well, thats all quiet depressing.


Remember, An amr 500 supercharger is only like, £120..

Search ROTREX on here,

People have used them on the FIRE motors over the years

 

[jrkitching]

The time you’ve declared all your mods and insurance premiums go up be cheaper to buy a more powerful standard car surely?

I declare nothing!!

Most folks here are too sensible to knowingly commit insurance fraud.

 

[Ralf S.]

Someone once said "You won't find the answers to life's problems in a bottle..."

They were wrong...



Ralf S.

 

[AndyRKett]

Can you port the head much on these?

There is scope to port the head, however porting is reliant on a good optimized intake system and a good exhaust set up from the manifold backwards.

The other issue with these engines is a very long intake manifold after the throttle body which is often made from plastic or at least half the manifold is plastic, therefore you cannot port a plastic manifold and therefore if the intake manifold is causing a restriction, then porting, bigger throttle body or new air filters may all be pretty pointless.

More air flow may make the engine feel more responsive, but it doesn't necessarily make the car any faster as already pointed out of the throttle body is fully open then there is a limit to the amount of air than can flow through that aperture.