Tuning P75 tuning

[Inosience]

Hey everybody, as the title says, I want to modify my P75 engine,
The plan is to modify the head, before putting it in.my cinq (yes I know this is the punto department, but the donor car was a punto 75)
After the MOT I will fot 4 36mm Kehin Carburators (with some help from my mates) but now is my question, what more can I modify ( but keep costs a little low if possible)
Thnx

 

[blu73]

You prob get more response posting in the cento section tbh...

But i would say fitting carbs seems like a step backwards really... ITB's would make much more sense, will use less fuel, run smoother, be more tuneable etc - the car industry moved form carbs to injection for a reason

As far as modding the bottom end is concerned, there isn't really anything that needs doing there, so long as its all in good condition the bottom end will take a hell of alot of punishment - The P75 should have oil squirters too which most FIRE engines don't so that should help keep piston temps down a bit. The most impotant part really will be the headwork, properly port matching and flowing that, fitting a better cam. The 866 P75 cam is a good cam but a Swiatek or C&B fast road cam will improve performance no end - and there will always be someone that wants to buy the 866 cam off you.

 

[Inosience]

yes, I know ITB work even better, but for a complete set, I pay somewhere around 200/300 euros, but for the carbs just 50/150,
But you say that with the carbs I will actually lose power??

 

[blu73]

well prob not over stock no but compared to ITBs they won't make as much power and for all the effort it just seems silly to not spend the extra... It would also mean somekind of aftermarket management though, either a full ecu or a decent piggyback system like a DET3. But what you then have is something that can go on a rolling road and properly mapped. It will cold start maps so you won't be back in the dark ages messing with manual choke.. They are just better than carbs.

I don't know the laws in Netherlands but you would never ever in a million years pass an emissions test that we have to pass over here in the UK each year for the MOT.

 

[Inosience]

Emisions is a problem for MOT, but for MOT I was thinking about converting it back to injection, seems like a ****load of work, but keeps the cost a bit lower, ITBs and another ECU will cost a load more,
Isn't there an option with ITB and original P75 ECU?
Not that I am affraid to spend, but she's getting quitte expensive at the moment

 

[blu73]

I'm sure a wizard like woj could possibly make it work but not many of us mere mortals could make it work properly.. A DET3 is not expensive, under £150 and easily one of the best piggybacks out there. Takes over fuelling and ignition so is properly live mappable, would be able to do proper sequential injection and not batch fire etc etc.

Remember you don't need to do all of this right now, you could just drop the P75 in completely stock and build up the parts over time. You could get all the head ported & flowed, skimmed to raise the compression a bit, drop a cam in and still use the stock mpi P75 setup, get a decent exhaust mani and all the stuff that would work if you went to itb's later, maybe an enlarged TB and polish the stock 75 mani even. You might even find after all that that you don't even need to mess about with custom inlet and ITBs or carbs... a well fettled P75 is gonna push 100hp without straining it.

Even at this point you could fit a DET3 or similar without changing to ITBs so that the setup could all be dialled in on a rolling road and be completely optimized and make as much as it can with the parts you have so far. And if after all that you are still hankering for more power then start thinking about ITB setup.

Of course, do want you want really, thats just what my approach would be

 

[woj]

(mind you blu73, location wise these are my potential clients, so weight your words and try to do more effective marketing for me ).

Not sure DET3 can do sequential injection, even more I am convinced it cannot.

The main problem with using ITB with the stock ECU is the algorithm - ITBs do not play well with the MAP sensor controlled speed-density thing. Might be a bit less of an issue with 8V, but on 16V as soon as you touch the throttle the MAP shows full atmospheric pressure and making a sensible speed-density map is almost impossible.

Modding the 8V ECU to work in alpha-n would be a nice challenge. I think I even discussed this with one of the Dutchies, might have even been the OP. (I was so deep into my 4AF project I lost track of what I was discussing with whom).

But now that this have been mentioned - I need to check some things back at home - it might be easier than I think...

 

[Inosience]

Yeah woj we already talked about an custom ecu, because I was planning to build a MPI turbo 1.1 but wrecked the car, and rebuilding it, so the turbo budget is gone
But now I want to build a fast 1.2 8v, starting with something like 75 horses, 100 could be a really nice goal and as blu73 said, it won't be really expensive, the goal for having the complete car finished is april 19 (Battle of the small) I dont't mind if the final setup isn't ready ofcourse

but blu73 also mentioned that a well fettled P75 could already pull 100 horses,
So i think this way it could work al little:
40Mm throttlebody,
Swiatek fast road cam
P75 exhaust manifold
Port and flow the head,
Max skim the head for higher compression
Removing Cat after MOT,

Or doesn't the stock p75 exhaust manifold do the job?

 

[woj]

OK, but that means there was another discussion with somebody then, because that one was about ITB.

I am not sure it is that easy to push to 100 hp with P75. I was "morally" helping with one not so long ago (but please, do not make me to try to reconstruct what was in it, proper cam for sure) and that one has hit the 90 hp mark. But indeed, without a remap which I guess can easily add 5 to the figure.

 

[blu73]

I am sure a P75 could make 100hp or thereabouts... The P75 exhaust manifold is decent but the Supersprint 421 mani will work better - but would be down my list if I had the P75 manifold already..

I think to actually hit or break the 100bhp you would be looking at fully worked head and decent cam and full exhaust with decat, Something TB wise - be it enlarged P75 one or something custom. Sure sparky5 could make you a larger P75 one.