Head Mods
Turbo Mini Forums

Guys

Am about to start gringing my head and would like to know what sort of CC i should be aiming for.
planning on running around 7-10 normally with the option of 14ish+ PSI boost

what do you think??

also some pics of chamber shape would be great (so i know where to take the meat off...

R.

Sooperdooperturbocooperexpertengineering!

How much you remove will depend what compression ratio you're trying to achieve, most people seem to aim for about 8-8.2-1 to run about 15psi.
You need to know piston dish volume, ring land vol, head gasket vol & volume above piston & below deck. Then you can work out how much you need to remove in order to achieve the desired compression.
Theres some chamber pictures here -

Cheers
Phil.

WWW.TURBO-MINI.COM

ahh... CR about 8. thats what i meant really. can calculate out then!!!

those shapes are very different. which way to go!!

keep the beak? and take out by plug hole?

Sooperdooperturbocooperexpertengineering!

Im going to loose the beak on mine.

Will do for now on lowish boost.

Don't assume you can just 'lose the beak'. Bend up some pieces of gas welding rod and have a feel through the waterway holes to see how much 'meat' is under the beak. You also get 'core shift' rendering some castings unsuitable.
The thickness of the casting can be seen throught he waterway holes aswell. This varies a lot, so judge which head to use (thicker the better!) For example, the head in the very last 1275 metros and early mini coopers were around 23cc as std and had a pretty thick deck. Given that these had the unleaded 29mm seats already in place, one of these is a good start!

Happy grinding!