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Discussion Starter #1 (Edited)
[lets look at a 350 with either 8:1 like you would normally run in a supercharged engine or 10:1 like youll want to run in a non-supercharged engine,with a cam that matches that 10:1 compression ratio in both combos

will it run? can I use it? will I be able to drive around town?

yes!

will it make decent torque?
no! theres not a chance in $%^$% that it will make good tq, at 8:`1 compression,and heres why
the work your engine can do or the rate at which torque can be applied is directly related
the both the average rpm range and average torque applied, and torque is basically the result of cylinder pressure.
lets look at the differance between an engine set up to run the correct dynamic compression and a low static compression ratio, both with a average performance cam.
now like I stated,lets pick a 350 chevy and a comp. cams xe274 cam.
heres the cam

http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-246-3

heres a chart with piston location in crank degrees

http://www.iskycams.com/ART/techinfo/ncrank1.pdf

heres a compression ratio calc.

http://cochise.uia.net/pkelley2/crc.htm

heres a DYNAMIC CPR CALC.
http://cochise.uia.net/pkelley2/DynamicCR.html

heres things to read carefully

http://victorylibrary.com/mopar/cam-tech-c.htm

http://www.crossedflags.com/community/viewtopic.php?t=6490


now I could get technical in the extreme and work it out for you to the exact psi for a given cylinderhead and gasket, etc. but the basic concept here is that if you compare the differance in dynamic compressed volume vs expanded cylinder volume youll find aproximately this

an 8:1 STATIC compression engine with that cam should have aproximately a 6.36:1 dynamic compression ratio while a correctly matched 10:1 STATIC compression ratio with that cam would have approximately a 7.9 dynamic compression ratio or the 8:1 cpr engine have about 25% less cylinder pressure. now on the surface youll think thats a 25% lower cylinder pressure but because the cylinder volume is significantly less in the higher compression engine when the ignition fires the true differance between the two engines effective working cylinder pressure is more than 30%.
so its not at all unlikely that a 10:1 compression engine that made 350 ft lbs of tq would make a minimum of 30% less at about 245 ft lbs with that cam thats badly matched to the compression available in the non-supercharged 8:1 compression engine.
remember the cylinder pressure in a supercharged engine is significantly increased with the super charger boost.and a 8:1 compression engine needs that boost to effectively make the correct cylinder pressure and tq, yet without that boost it has little potential to build cylinder pressure effectively. but once supercharged,it gains extra power due to the greater volume of fuel/air mix burned.
remember that formula fo hp?
torque x rpm /5252= horsepower
well given the 30% PLUS loss in torque that lower compression is a significant handicap to making the necessary cylinder pressure(torque)

and yes Im well aware that you should only gain or lose about 8%-10% if the cam is a reasonable match to the lower compression ratio due solely to the loss in cylinder pressure alone! but if you miss match the cam and it bleeds off significant cylinder pressure due to a delayed intake valve closeing in relation to the piston possition the engine performance falls far faster that the loss of compression alone would normally cause!
 

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Quote-an 8:1 STATIC compression engine with that cam should have aproximately a 6.36:1 dynamic compression ratio while a correctly matched 10:1 STATIC compression ratio with that cam would have approximately a 7.9 dynamic compression ratio or about 25% less cylinder pressure.-Quote

Wouldn't that be more pressure, not less?:huh:

So a 8.1 static CR with a stock cam, and then switch to smaller cc heads raising the CR would have both static and dynamic ratios increased, yes?

In that case, with the stock cam and higher static CR, would not the dynamic CR be too much?
 

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Discussion Starter #3
sorry for the miss print, your correct, I corrected the sentence
 
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