Increasing compression ratio by skimming

[A1ex]

There is only so much you can skim off them to be honest, having seen the underside of the head there isn't much spare metal to take off it. I'd be surprised if you could take more than 4 or 5 mm off it but at the same time I've never actually done it either.

I got it as 0.04 CR per 1mm skimmed so if you did say 5mm you've still only gain 0.2 CR and there won't be much of a head left. You can increase it much easier with pistons. If you already have 11:1 (a7) in your accord there isn't much benefit for going far past it perhaps 11.5:1 at a push. This is from others knowledge not my own.

[A1ex]

Just double checked my calcs and did the cylinder area wrong, calcs after a full days work! DOH!

Anyway, better results, it's actually double what I had so 0.08 CR per mm so a skimmed a5 would be about 10.15:1