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6 point something compression ratio
Back in the bad old days (racing motorcycles, etc.) a fellow my the name of
"Pops Yoshimura" (his bikes won at Daytona) told me that high compression
ratios were not the holy grail of horsepower.
In fact, if you go from 6.0 to 1 all the way to 10.0 to 1, you'll pick up
all of about 10% HP increase. But everything works harder - bearings,
pistons, engine is harder to start, rougher, and requires expensive, hard to
find (nowadays) high octane gas to prevent pre-ignition, which destroys engines.
Of course, higher published compression ratios make it easier to sell cars
to people who _think_ they understand these things under the theory that
more is better, but here, it is not.
Some of the best, longest lived, smoothest engines I've ever owned had CRs
under 8.0 to 1 - example 500cc BMW, 1958 vintage. Ran on anything, started
easily, one kick, sold it at 100,000+ miles - never rebuilt!
Besides, if you use high compression PLUS turbocharging, you'll need 200
octane gas - heck, we have a hard enough time buying 93 octane nowadays.