Need help determining compression ratio...
01-11-2011, 02:26 PM
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Need help determining compression ratio... A friend built a 403 inch turbo motor with Callies 4” 4340 Forged Crank,
Callies LS2 6.125” Forged Connecting Rods, Diamond Forged IBF Race Pistons 28cc Dish 9.2:1 CR 4.005 Bore, it has a stock LS2 cam and ported stock 243 heads.
My motor is now coming up to 115k and is showing signs of getting very tired. It has 64cc 5.3 heads, and LG G5x3 cam installed and I'm curious if there is a way to calculate if we replaced my heads with the 243's as well as my cam with the stock LS2 cam what my compression ratio would be? I have a chance to pick this motor up for an absolute steal but would not be running any sort of forced induction on it other then a 150 shot and the motor would be a daily driver.
Callies LS2 6.125” Forged Connecting Rods, Diamond Forged IBF Race Pistons 28cc Dish 9.2:1 CR 4.005 Bore, it has a stock LS2 cam and ported stock 243 heads.
My motor is now coming up to 115k and is showing signs of getting very tired. It has 64cc 5.3 heads, and LG G5x3 cam installed and I'm curious if there is a way to calculate if we replaced my heads with the 243's as well as my cam with the stock LS2 cam what my compression ratio would be? I have a chance to pick this motor up for an absolute steal but would not be running any sort of forced induction on it other then a 150 shot and the motor would be a daily driver.
01-11-2011, 02:40 PM
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Thanks John, the motor right now is at 9.2, so with a .040 gasket would take it to 9.4:1? In your opinion would it even be worth it as a daily driver or just be very sluggish due to the lower compression?
01-11-2011, 03:54 PM
#4
On my calculator that motor with a 64cc head on top of it, which is either of the options you have listed, comes in at 9.0:1 with a stock gasket. With a .040 gasket my calculator had the motor at 9.2:1.
As far as daily driving that motor it wouldn't be too bad it would just really lack low end power. Once you got higher in the RPMS it would do alright but the low end grunt would not be what you expect from a motor that size. If possible I would try and mill those heads a substantial amount and get some more compression in it. That will pick up your low end power and make the motor more tolerable down low.
As far as daily driving that motor it wouldn't be too bad it would just really lack low end power. Once you got higher in the RPMS it would do alright but the low end grunt would not be what you expect from a motor that size. If possible I would try and mill those heads a substantial amount and get some more compression in it. That will pick up your low end power and make the motor more tolerable down low.