Lowering Compression Ratio

[Vasi]

I'm currently rebuilding a blown 1380 Metro Turbo engine to fit in my mini. The problem is it needs about 20 thou taking off the head (Avonbar stage 3) and about 40 thou taking off the block as it blew across 2 and 3. A quick calculation suggests I'll need to increase combustion chamber volume by 6.37cc to maintain the original CR.

Currently it has 73.5 Omega (Turbo?) pistons, I was wondering are there any other pistons I can get that will lower the CR more?

Or perhaps there is some other method to lower CR that you can suggest.

>>> Edited by Vasi on Sunday 11th April 13:56

[egomeister]

Could you find a thicker head gasket? I think this would have the same effect, but I'm sure someone more knowledgable will clarify in a bit.

[Cooperman1]

You could open out the cylinder head chambers a bit, use the thickest head gasket which is suitable - be careful here as you still want a high quality item.
Then all that is left if the ratio is still too high is to machine the pistons down a bit. You can check the thickness of the piston crown and it is probably safe to remove about 15% of that thickness to give more capacity and thus lower the C.R.
Do your calculations very accurately to avoid problems in the future.

Peter

[Vasi]

Thanks guys Avonbar supplied all the kit originally so I'll ask them about the best gasket to use.