Join Date: Mar 2006
Location: Coldwater, Mississippi
Alexandros: you may be right about the 1 more CR for every 3 lbs of boost, but I will have to disagree with you on only running 7.5 psi with 8:1 CR with 93 octane. brian is right when he says its in the tuning. i, personally, have not yet experienced this, but i'm definitely doing my research because I have a 10:1 setup that i haven't put together yet and am planning on opening up my combustion chambers some try to get it to 9:1, which WILL be fine. I plan on having 8-12 psi of boost and still run 93 octane. The key to any engine running its best is fuel/timing balance. With the added boost, this balance will have to be brought to order by taking away timing and adding fuel, for the most part.
With N/A, 10.5:1 is the CR limit to lookout for if you're wanting to run 93 octane because I believe retarding the timing with N/A will only hurt.
With boost applications, compression ratios after boost is added is generally not calculated, but if you wanted to take a look at a very simple, non-extreme example, plenty of people have put 10 psi on the stock 8.5:1 bottom end of a 5.0, and they have safely driven their cars for more than just 9000 miles with 93 octane. If you calculate it according to your conversion, final CR would be at 11.83:1, correct? With the correct tuning, those boost numbers have been raised even more.
brian: as long as you have the build to bare it (i haven't paid attention to your sig), i believe your ideas are possible. the 110 definitely helps, and the tune is going to be the key, so it goes right back to what you said first
'89 SSP 306 12.96 @ 105 mph SOLD