Tuning confused / colombo 273 with spi vs 75 head mpi

[mozart]

hi i have my sei spi with regrided cam ( dont know the specs ) chip from weber for 7500 rpm and colombo 263 cam / punto 38 mm tb supersprint header and exhaust .is it better to put in the 273 colombo cam with abj gear or with the same money put the punto 75 head with mpi my ecu and chip and my regrinded cam ?

 

[fingers99]

I don't know the spec of the C & B cam, but my best guess is to go with that -- C & B don't mess around. There's little point in going MPI unless you're going full race and the P75 plenum is nothing super special.

You'll need to do some very careful and elaborate measurement of any unknown cam to be able to even guess whether it's worthwhile (lift, duration, overlap, etc.) Chances are it'll just be a reground P75 cam.

 

[mozart]

fingers i know the c&b specs is 273 with 10 or 10.5 as it is brand new
i do not know the specs of my reprofiled cam that i already have ....

 

[medion6969]

I had the max road columbo and bariani 280 s cam in my last 1108 engine and it made the 866 cam look useless,go for the good cam

 

[mozart]

as i see in the polish club c&b 280 and 75 head is killer combi...with dynos near 100 hp

 

[fingers99]

But I can't see any of that coming from the head. It's quite unremarkable. The cam is fairly good (the P75), the exhaust manifold is excellent, but the plenum is only so so. TB is obviously an improvement over the stock 1108 one, but will be behind ones bored out to 40 or even 41.5 (!) mm.

It would be worthwhile trying to find out what the Trofeo cars used -- they ran MPI from an SPI ECU.

But take a recipe and follow it (or make your own). Let us know how you get on.

Remember, there once was a Cinq in Greece making nearly 400bhp (albeit with a turbo 1.6 Punto GT engine) -- the Poles have yet to come close!

 

[mozart]

fingers i read somewere that the p75 had bigger intake valves and the intake ports are better shape as they are behind valves ...also i take the head ported and polished so with the cost of 200 e (just head and in manifold) is better deal than take my head for headwork .one friend of me who racing a sei had see 17 % gains with this head but on a twin tb combo kit kar.

 

[medion6969]

ive got a p60 and a p75 sitting in the shed so I checked the valve size and both heads are identical valve wise

 

[fingers99]

I've read that stuff about the inlet valves, too, but honestly can't see any difference between them and the later MPI Sei. Never got round to measuring, but have scrap P75 head knocking around somewhere.

To be sure, the port entries are bigger on all the MPI heads, but that doesn't always correspond to better gas flow.

Guy Croft is no fan of the FIRE engines, but has done work on full race ones and is often a source of very good information. One of the straightest people I've ever encountered.

 

[mozart]

hm not too many post in croft s forum about fire .....
medion 6969 i am interested to buy your c&b if you want to shell it ....

 

[mozart]

so punto 75 has larger / better shape ports and bigger valves .is it worth to change just the head (of 75 ) and keep my spi manifold and intake ?or the 75 intake manifold is better shape ? also i hear that is posible to fit a 16 v intake manifold and tb ?( my tb in spi is already 38 )

 

[medion6969]

sorry bud my bariani cam sold very fast,as well as all my other 8v engine mods,in fact same guy bought the whole lot

 

[medion6969]

p75 head has larger inlet ports so the mpi injectors can get a better line of sight into the combustion chamber,not really suitable for spi use.plus the top studs are wrong place anyhow

 

[fingers99]

so punto 75 has larger / better shape ports and bigger valves .is it worth to change just the head (of 75 ) and keep my spi manifold and intake ?or the 75 intake manifold is better shape ? also i hear that is posible to fit a 16 v intake manifold and tb ?( my tb in spi is already 38 )

It has larger ports. Larger does not = better. The larger ones may flow worse.

It doesn't have larger valves.

The 16v stuff I find completely unbelievable. Some of the Poles are running 41.5 -- note that here we're talking throttle bodies, not carbs, so that it's quite difficult to go "too large".

You seem to be reading what you want to read, rather than what people write. So why ask in the first place?

Good luck with it.

 

[mozart]

thanks fingers you are right so better stick to my set up with a better cam( colombo 280 )

 

[cc1]

My 1.1 Mpi with some mild porting, 866 cam and SS manifold seemed to have more power top end than my current 1.2 Grande Punto engine which has at least 30% bigger inlets and similar cam, plus the valve stems are narrower also.
The 1.1 was not running optimally, but the Ecu did well to cope with the changes.

With regard to the 1.2 engine:
Now the engine parameters have changed dramatically, the Ecu has hit it's limitations in adapting, and is almost happy to run the injection system as if it was a 1.1 even though the capabilities are there.

The primary factor in tuning an engine is having an Ecu you can remap to suite any changes. Without this ability you will hit a wall and even fitting a race prepped engine is a waste of time and money.

 

[mozart]

sorry the colombo i have find is the 272 from punto gt ( turbo )
is it good for n/a or give the double price and go for 280 ?

 

[fingers99]

Punto GT cam will never, ever, fit a FIRE engine.

Are you looking on C & B's website?

 

[mozart]

yes ....punto gt here in greece put the 866 cam in their heads ...
also there is a colombo 272 colombo for the turbo gt and i can find it cheap and used ....the colombo 280 is 380 euros here and i can fint 272 with 100 euros ...
but there are diferences in exhaust lift ....i do not know how much this affect power ....

 

[fingers99]

But it's a completely different engine!

You might as well talk about putting cams for a Volvo engine in a Toyota!