18cc pistons head & boost
Turbo Mini Forums

Hi just thinking on getting some omega 18cc from avonbar or med I've got a block that's never had a skim but needs a bore to a min 1293. I have a good ported head (12g940 if that's the right number you know witch one I mean) that's never been skimmed either & has totaly std chambers. now what sort of cr would I expect to see with that kind of combination & what sort of boost levels would be safe to run with? thanks scott

Edited by scott the joiner on 28th Apr, 2011.

Sorry buddy. Could you edit that post into sentences please? I'm struggling to make any sense of the post as it is.

If something is worth doing, it's worth doing half of.

I think you need to use this.

http://www.csgnetwork.com/compcalc.html

All the questions posed on that page require answers to answer the overall question.

From the figures given - about 8.7:1

Boost ? depends on a lot more than just CR -intercooler ? Ignition setup ? fuelling ?

I've got an intercooler set up on & ignition is std metro turbo dizzy mite go mj in the future & fuelling will be adjusted & set up accordingly its currently set for 12.5 psi boost

If it is 8.7:1 then you could run loads of boost.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I've got the same set up.
18cc accralites. 1293 block with minimal skim. Standard turbo head that's had a minimal skim and converted to unleaded.
I've got a later dizzy that is not the turbo one but it has been altered by the guys at h&h ignitions to give me the correct advance curve.
Im also running an intercooler.
With my set up i have found 15 psi safe, however a couple of weeks ago i started pushing the boost up and the head basket gave way at somewhere around 20 psi.
I'll only ever take mine now to 18 psi in short bursts.

Edited by madcatminis on 29th Apr, 2011.

I have a cr of 8.5:1, run a cossie intercooler, timing set at 25 degrees and I accidentally put 18psi through it when I split my signal pipe from actuator, everything was ok, no det etc.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

So about 15 sounds the safe bench mark for everyday use. Matcat have you any chamber mods at all? Or totaly std chambers? Bennyy is you timing fixed to 25deg across the whole rev range? & is it a dizzy or mj? Cheers for your help just need to plan me new build

So about 15 sounds the safe bench mark for everyday use. Matcat have you any chamber mods at all? Or totaly std chambers? Bennyy is you timing fixed to 25deg across the whole rev range? & is it a dizzy or mj? Cheers for your help just need to plan me new build

15psi should be fine if fueling and timing are good, and mines just a turbo dizzy mate.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Yes. Totally standard chambers.

Bennyy is it a std turbo dizzy or has it been played with to lock it at 25deg or just std metro turbo still using the vacume advance with std curve thanks this is helping me loads after my rr set up the bloke put to much advance on & killed me engine so got to start from scratch

just a standard turbo dizzy with vac advance disconnected

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble