Polini corsa ports

[StepVino]

Hi, I'm installing a Polini Corsa for a minarelli hor, ac.

I measured the port heights, and I get this which seems
very low, especially the intake ports:
Exh 175.5, main and aux tranfers 111.4, and boost 104.6

I haven't installed the cylinder yet, so I guessed 0.7mm deck
height for calculating the port timings. Does this sound like a
Polini corsa, or could it be something else? It does say Polini
on the iron cylinder.

thx

 

[tiba_karotsu]

sounds like Polini Corsa timings, did you factor in squish/deck clearance when you measured the port height?

 

[StepVino]

Thanks Tiba, I got used to not having a cylinder head gasket, so
for me deck=squish. That probably won't be the case this time, so
deck will probably be smaller, and timings even lower.

I'm surprised that the operating rpm from Polini's site (166.0076/R)
is 10.6k, if you go by the timings listed in Bell's book, these timings
correspond to under 8k. I'd like at least 11.5 out of it, but not
necessarily right away. I was going to install it unmodified, just to
see what it does, but maybe it would benefit right off from widening
the exhaust a bit? It looks small.

 

[tiba_karotsu]

yup it will, i kept my exhaust port timing the same & widened it to 68% of bore width, i raised the transfer ports a bit in a staggered manner so teh main opens first & the boost port last.

the Corsa LC cilinder has it's combustion chamber protruding into the bore & i have set my squish at 0,90mm so it can run on 93 octane unleaded, right now it has 180ex/126main/124sec/118boost but for now i think you should leave the transfers alone until you get the exact port timings.

 

[StepVino]

Ok, thanks!

Edit

Here are some pics of the mod. Marks on the
piston crown 47mm x 0.68 cm apart: