NOT850 wrote:
Would there be much difference in output of the engine between a compression ratio of 9.5:1 compared to 10.5:1?
Some difference, yes, but again, it is all about the package. There is not much point going for 10.5:1 compression without cam and head mods to suit. You could make things worse if you do certain things without the others - like the valve springs and cam combination. You might get 10% difference in numbers at the top end, maybe 5% torque difference, but what does that mean when driving it? Unless you are trying to knock tenths off a qualifying time at the track, there is not much point.
Design the whole package around what you are trying to achieve, but don't worry too much about the numbers up front i.e. don't say "i want 70hp atw", say "a lively and fun to drive car - and reliable based on a 1098 engine". That is what i did with my engine build, and quite honestly i was surprised by the numbers on the engine dyno, but far more importantly i am absolutely stoked with the way it drives.
Having said all that, IMHO, 10.5:1 with appropriate cam, head etc would make a very good 1098 road car if you are prepared to stump for 98 octane fuel all the time.
cheers
michael
_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by
http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates