Decking block cost??
who says you have to have 9:1 to run boost?
Nobody. But that figure seems to be the limit for turbocharged engines, generally, in regards to what is feasible for engines utilizing 20-25 pounds of boost. The idea that you could get away with running 10.5:1 compression would suggest C-16 fuel (or, E-85, or outright alcohol) and reduced timing, with less boost to stay away from detonation.
It's all a trade-off, of course, and 9:1 is not a magic number, but seems to be the most practical for street-driven cars because they can usually get by with pump gas when used with chemical intercooling and an actual air-to-air intercooler up front.
If you want to run more than 9:1, you are looking at reduced boost, timing, and higher octane requirements as a nod to reducing detonation possibilities.
Overall, there's reason most systems utilize 9:1 as a limit on compression... a practical consideration...
That's the way I see it, anyway.:headbang:
