Why lower cr on n/a engine than turbo??
Turbo Mini Forums

Just gotta a+metro engine No 12he72 104126,I checked it on mini resources site and its unleaded 9.1 cr,Turbo block is 9.4 Baffled.(can't afford the 18cc 73.5 je's at mo)

Are they deeper dish pistons than turbo or short height

What sort of intercooled boost would it take on the orig pistons short Term(say 500 miles).Prob using a 27cc vmax head(group a) on the block.

Would I be allowed up avon in a MINI metro or is it just mini,as I'm thinking about sticking summit in the metty for a bit of development work(more space in engine bay to work on things,in car diff changes etc) then transferring it to my mini shell later on

Metro turbo weekend driver,Mini turbo in the making again!

stuart wright has been using dished standard pistons for some time , it was running 18 psi bost which gave 182 bhp on the rollers last visit, make sure the pistons have drillings around the oil control ring grove rather than a slot , the je's are deeper dish , the ones i have seen required an amount to be ground of the top of the rod as there was not enough clearance obove the pin -!! not ideal

Edited by stuart gurr - vmaxscart on 27th Mar, 2005.

Stuart,

Mr S. Wright always uses forged omegas I believe?

Most 1275 metro engines were 9.75:1 CR. I've Never heard of a 9.1:1 as a stock CR on an A+ ???

Unleaded Metro Engines

Metro 1000, '89 on
Metro 1275, '89 on

99HE38/39, 8.3 CR
99HE35/67/68/69/70/76/94, 9.6 CR
12HE24,35,39,40,41/42/67-75, 8.0 CR
12HE24/25/48/71/72/73, 9.1 CR
12HF, 10.0 CR

Cars a 1990 12HE72 104126 number ?????

Metro turbo weekend driver,Mini turbo in the making again!

So according to that list, a 12HE24 or maybe a 12HE72 could be an 8.0:1 CR OR a 9.1:1 CR???

That doesn't sound right to me at all... Why bother having numbers if they don't relate to the engine internals?

http://www.manchesterminis.co.uk/technical...ngine_types.htm

...Gives significantly different results...

I really can't see them dropping from 9.75:1 to 9.0:1 just because of changing to unleaded fuel...
Interesting that there were two different MPi CR's

Take it as a 9.4 then,would it have the same pistons fitted as a standard turbo.

Any idea on standard turbo dish size

On the mpi c/r I had a head of one a while back and it only had 15/16 cc vol

Metro turbo weekend driver,Mini turbo in the making again!

Standard Turbo pistons have a 12cc dish.

Phil.

WWW.TURBO-MINI.COM

Interesting stuff, I've seen some MPi heads that definately had at least 23cc - and these looke to have a pretty meaty deck aswell - ideal for turbo chambers!

Regarding pistons, They definately won't be 'turbo' items. These were ONLY fitted to the turbos. Assume a 9cc dish at a guess...

metro = class x
class x = non mini

WTF?

Anyone else know what Nik is talking about?

bottom of the 1st post dave

oh, so obvious now!

yep i had a mpi head which had 23 cc dish as well as 33mm inlets, pity i had it worked on for my NA 1380 ended up with 19cc, 37, 29.3 valves but still never mind.

always looking for them bigger bunches of bannanas