Originally Posted by
Marce
How thick should an unmodified 8:1 compression ratio 2.25 litre Series 3 petrol engine head be, and how many mm would need to be skimmed to raise the compression ratio to 9:1?
I put this question to the Facebook page of this forum and two people suggested, without referring specifically to this engine, that to raise compression ratios by that much I should be looking at domed or high crown pistons to avoid valve clearance or timing issues. But ACR in England skim these heads to 9:1 and I've heard of other people doing it successfully. I just don't know precisely how much needs to be taken off.
Do ACR just 'skim the heads' a set amount or do they measure the capacity inside the combustion chamber at TDC and then work out how much to remove to get to 9:1 ?
Not sure about valve to piston clearance because I haven't played with the 2.25 motor but it seems a common modification so should be OK.
9:1 compression - Series Forum - LR4x4 - The Land Rover Forum
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