I don't see that 210 as a bogus number. Others achieve it on other outboards and the quasi-adiabatic heating during compression could explain it on a tight 4 stroke.
Quote:
Originally Posted by Bushwacker
210 psig is almost certainly a bogus number because that works out to be a compression ratio of 15.3:1, which is way too high, even if you're running 103 octane Av gas with aluminum heads!! I'd see if you can find what the specs are from a Zuke service manual. 85 psig does sound a bit low for the 150, so it may have some stuck rings and need a good decarb. And compression ratio primarily affects BSFC, but has sort of a 2nd order effect on power. And if you have to back off on spark advance to avoid detonation with the high compression ratio, you will lose more power from that than you will gain from high compression. I own an old muscle car and the race block I bought for it turned out to have about 12:1 compression ratio which is way too high for premium pump gas, so I tore it down and installed 9.5:1 pistons in it!
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