Comp. Ratio effective..static???
12-28-2005, 12:00 PM
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Comp. Ratio effective..static??? could use a little help on this one. in the process of planning a forged shortblock LS1. I am running a Procharger currently @ 10 PSI eventually going to 15-18 PSI. On a 3.898/3.905 (don't know yet) Bore, 3.662 stroke, rods @ 6.1 (scat). Current cam intake closes @ 44*ABDC
I noted one board member running upwards of 18 psi with 10:1 static on his 427. However not sure what cam and effects thereof he is running.
My thought was to run a set of the new PP 243 with a 64CC chamber, then once I finalize my FI solution for higher boost change to a set of ETP 225's @ 72CC. Just a wild guess on my part, I was thinking of a static cr somewhere in the mid 9's....I think jumping to mid 8's on a low boost application would give me some drivability issues, and cruising MPG would most likely suffer.
My question is this: running 91 oct. (CA) what is the maximum effective compression ratio I can reliably run? This would help in determining the static ration and whether I need a cam change or not.
Is there really a difference in how boost is achieved...ie turbo/SC when making this decision?
what effect does a point in CR have on cruising efficiency..ie MPG
Piston choices are limited with 64CC heads and anything in the 9's, most manufacturers jump straight to mid 8's, with most choices 10 or above.
Would really like to hear from some experts out there...
Thanks
I noted one board member running upwards of 18 psi with 10:1 static on his 427. However not sure what cam and effects thereof he is running.
My thought was to run a set of the new PP 243 with a 64CC chamber, then once I finalize my FI solution for higher boost change to a set of ETP 225's @ 72CC. Just a wild guess on my part, I was thinking of a static cr somewhere in the mid 9's....I think jumping to mid 8's on a low boost application would give me some drivability issues, and cruising MPG would most likely suffer.
My question is this: running 91 oct. (CA) what is the maximum effective compression ratio I can reliably run? This would help in determining the static ration and whether I need a cam change or not.
Is there really a difference in how boost is achieved...ie turbo/SC when making this decision?
what effect does a point in CR have on cruising efficiency..ie MPG
Piston choices are limited with 64CC heads and anything in the 9's, most manufacturers jump straight to mid 8's, with most choices 10 or above.
Would really like to hear from some experts out there...
Thanks
