8.5:1 cr
Turbo Mini Forums

if you have a 10:1 cr motor with 21cc in head chamber & piston dish with 7cc
to get this motor to 8.5:1 cr with 24 cc in head what cc piston dish would you need to drop cr to 8.5:1?

From the 10:1 and the head/piston volumes stated, I have assumed this is a 998cc engine??

Anyway, with your 24cc head, you would need approx 9.5cc in your pistons to get 8.5:1 CR.

This is not that accurate, and assumes a lot of things, as well as ignoring head gasket volume, ring land volume etc. But you get the idea.

sorry forgot 1380 motor

In that case, 12cc pistons.

Although that assumes 10cc head gasket/ring land volume, which is a shade high maybe?

8.5:1 C/R
would be good for boost levels of around 14psi of boost with a decent intercooler on 98 ron fuel

this would give you a "slight" margin of safety!

without intercooler you would down to 11ish psi of boost if your lucky!

the above i have stated is without mapped ignition which would place you in the realms of further boost potential and a better drivable motor.


something to think about!
formula 1 engines of the 80s period, when turbo charging was allowed their C/R was 6.9:1

run on a witches brew of fuel producing 1500HP from a 1500cc engine

BEN:

Edited by BENROSS on 18th Jan, 2006.

wolfie try making some more this year for avon park weekend out,

iam sure it would suppress detonation until
at least 60psi of boost!.....lol

oh, please stop reminding me of avon park 06, I am looking forward to it already, and its months and months away, and more to the point I am stuck at work!

Edited by Tom Fenton on 18th Jan, 2006.

throw a bloby in for a fortnight tom

theres no medals (been there)

yes it is tempting to have a week or two on club.......

it will soon be summer and trackday season and all will be much better! I hate winter, it drags and is dull.

ok ill get a home brew kit tomorrow

Mmmm 110 octane vinegar lmao

You need an extra 7.67 cc combustion volume to drop it to 8.5:1 so with extra in your head as Tom correctly sais 12cc pistons.

For 8:1 you'd need 15cc dish.

I am consideing buying a plane ticket whilst they're cheap... Should I / Shouldn't I ....Hmmmmmm

Edited by turbodave16v on 19th Jan, 2006.

Dave, do it, you know it makes sense........I'm sure you will not be stuck for a drive or two either.........

make it happen dave

you cant miss out ...............Can You!

do it dave!

Team Racing

Go on Dave, you know you want to!!

-MINI CLUBMAN 1380 TURBO-

do it dave, let you have a drive in my new motor.

16V project underway

do it dave!