Skim 1275 cylinder head
Turbo Mini Forums

Does anybody know how much a standard 12g940 can be skimmed? and how much thou for each cc removed?

I have a 1263cc short stroke A+, 8.5CR engine built to run my Eaton M45 charger, but im considering selling the Vmax kit to fund my turbo project and going the n/a route with skimmed head. Cant realistically afford 2 forged induction cars, especially with fuel prices.

I need to get around 15-16cc in the head to bring CR to 9.5-9.7, but not sure if it can be skimmed to that degree. Im running a sw5 cam and 2.76fd and just looking for smooth drive, not massive power for long show runs ie L2B, Riv Run etc.

I have a 15k unleaded standard head of a 94 sprite that I wish to use. I dont want to skim to current Vmax Scart stage 4 head as I will change the whole engine later in the year.

I have just rebuild and installed the engine into my clubman this weekend and didnt fancy taking it out to swap block and pistons. I would possibly keep the M45 expect I am having big problems with getting it started from cold due to fuel struggling to reach chambers from carb. ( Will post seperate thread)

Class C 3rd Place Avon 2011 14.18 @101mph

what pistons does it have in?
is it running a de compression plate?
im not too sure you can reduce the head combustion chambers that far

Yes i moved to the darkside

Instagram @jdm_brett

It as +40 10cc cast Omegas pistons, 6.8cc decked height above the pistons (already been decked 0.040), due to short stroke crank, s rods etc.. The simple thing to do is deck the block a further 0.060", but that means taking out and striping the engine. Really want to go to L2B and still got to MOT, Rolling Road etc.

No decom plate. thankfully

Edited by alaskanow0 on 12th Apr, 2010.

Class C 3rd Place Avon 2011 14.18 @101mph

I would suggest measuring the depth of the oil passage in the head and subtracting it from the total thickness of the head. The resulting distance can be reduced to no less than 0.080 in (according to the yellow bible)

All heads are not the same so the resulting chamber cc will differ from head to head.

I have a head that measures around 18cc so i would think that 16cc is obtainable but would depend largely on the head itself.

cheers
Dan

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

I've done 15cc..

10thou is "approx" 1cc, but it depends on chamber shape obviously.

mine is less Vegard, its 14cc

And then it'll look something like this:

Are you proud of that picture Vegard? its probibly the one you post the most.

Some one slipped with the die grinder though

Ok, I used a piece of graph paper and pencil trace the chamber size, works out at 31cc surface area, therefore 31cm x 2mm (0.080) = 6.22cc taken from the standard 21.4cc giving me a 15.18cc. I cant find my yellow book, but found another Vizard book, how do you measure down the oil hole on a 12g940 as its not straight? Where else can you measure?

Edited by alaskanow0 on 12th Apr, 2010.

Class C 3rd Place Avon 2011 14.18 @101mph