Info on a cam.

[Ruan]

Higher compression = better thermal efficiency, i.e. it'll extract more power from the fuel... But if you're turbocharging an engine, you're increasing cylinder temperatures due to increased pressure, higher temperatures = a recipe for knocking which is damaging.

Lowering the compression ratio will help reduce cylinder pressures and therefore temperatures, producing less power.... But obviously when you add turbocharging to that, the slightly lower CR is totally offset by the increase in air you can stick in due to turbocharging... Have a listen to high power, turbocharged engines, they sound VERY easy to spin over *wheeeee* rather than *Rahchachacha* from each piston lifting and coming under load - that's because they've got shit all compression!!

What Ripp is on about with the Squish is where there's an area that causes turbulence and forces the charge to the centre of the bore... If you reduce compression by skimming the pistons or putting a decomp plate in or 2 head gaskets, you reduce that squish area, so the mix will burn unevenly and end up with parts of the mix burning long after TDC, causing crap combustion.

That's as I understand squish area... Ripp please correct me on that one...