Hi Alex,
You’re interested in getting POWER out of a little engine? I studied Jan Olson’s thread JO’s gasified Volvo thread. There’s just a huge amount of info there.
Sample: subaru has an interesting engine construction, ej18, ej20 and even ej25 have the same geometry, so the cylinder heads can be easily installed between the mentioned types. So I installed the ej18 engine heads on the ej20 and replaced the original 1.6 mm thick gasket with a 0.6 mm gasket so the mathematical compression ratio is somewhere around 1:13. in the original it has 1:10
Rindert
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