n/a pistons
Turbo Mini Forums

after looking at some previous threads about using the standard pistons for a turbo engine, im still abit weary

in short, could i use my standard SPI pistons for my engine if i were to get them machined. im looking to run around 10 psi, 12 max, with intercooler,phase 2 cam standard ignition.

any help would be great.
thanks
jamie

'always keep a spare shot for a stray bird'

to be honest in my book i think 8 psi is is much safer!
with those pistons

at & above 12psi is in the twilight zone

I agree with Benross, you might get away with it for a little while but sooner or later it's going to bite you.

No reason why youcan't use it at 8 ish psi whilst you get the car shaken down and the instalation proven, that way you can build another motor out of the car when time and money allows meaning you spend more time driving and less time clibing over it in a garage!!

8psi on a reasonably high CR will be quite good fun anyway, probably around 100BHP+ with the SPi cam in there.

Every day is a school day ...........

How fast and how expensive ...... the same question...

on the same subject am i right in saying that you could leave the n/a pistons as they are and lower the compression with reproflied combustion chambers?

me and Ja have been speaking about this but i wasn’t 100% on the subject..

what kind of psi could you run on that set up? (assuming good intercooler etc)

You can lower the CR by modding the head but that's not the whole story. The problem with the standard SPi pistons is one of strength, not just the resulting CR.

I wouldn't trust them for boost much higher than 8ish long term as has been said. However to get the car running as a turbo and sort out the inevitable istalation hic-ups it would work fine. Anybody who has run a Mini at 8 psi over a 9 and a bit CR will tell you it is a nice road machine and lots of fun.

Every day is a school day ...........

How fast and how expensive ...... the same question...

cheers guys, for piece of mind i mite fork out for some turbo specific ones.

any suggestions for my setup?
and i dont wana spend the earth on them.

Edited by fordimus maximus on 21st Jan, 2007.

'always keep a spare shot for a stray bird'

The megas seem to get a lot of praise but I've not used them so can't make a personal judgement.

Every day is a school day ...........

How fast and how expensive ...... the same question...

Please keep all your piston questions in one thread, you're making it impossible to remember what you're on about.

So on to helpful mode :)

As far as I know, the SPi pistons are exactly the same as turbo pistons as long as you keep compression the same. I know that the SPi ones are of the "slipper" design, but in all honesty I don't think that this is so important.

If you're buying new ones, the Megas are tried tested and found to be good. End of discussion.

troublw with the slipper pistons is the oil grove, this is a major week point weres decntt pistons uses holes which are much stronger.

having said that there is no reason why you shouldnt use the engine as it is and as said before get all the instalation hic ups out of the way and go from there.

i ran 9.8 cr on 10 psi with a intercooler with no probs as long as its set up right with a fixed advance or a mega jolt set up. it went bloody well to be fair and kept good economy.


im using mega pistons at the moment and considering how much boost i was running last year 9.4 at 12 psi a lot of the time they are still in new looking condition even after all these yaers ive been using them in NA set up as well.

always looking for them bigger bunches of bannanas

ok thanks chaps, sorry for all the thread hopping, my bad

'always keep a spare shot for a stray bird'

your help is brilliant. but looking at going new now. i have been looking at the morspeed 21253's 13cc dish.
the guy i spoke to there suggested that i have the head skimmed if i went for these. is there any truth in this or would these be fine for my application.

sorry for dragging this out just want to get it right first time around

'always keep a spare shot for a stray bird'