Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.89 :1. Your dynamic cranking pressure is 183.23 PSI. Your dynamic compression ratio is 8.89:1. With the stock cam ( specs from Sealed Power stock replacement listed at Rock Auto ) To see what the effect of boost pressure and altitude is on your static compression ratio, s imply enter the three variables and the calculator will display the results in a new pop-up window. The ability to precisely deter-mine both your displacement and compression ratio is a vital tool for anyone making alterations to a. Boost Pressure in PSI : Static Compression Ratio : (:1) Target Altitude : (Feet) RSR. Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 6.83 :1. Running Boost from a blower, turbo or other device, then you will want to try the Effective Compression Ratio calculator. The formula simplifies to: (D + BVTDC + CC) / (BVTDC + CC) CR. The 142 only puts out about 4-5 lbs of boost so it is not as hard on the internals as a 6-67 or 8-71 can be. If your comp ratio is over 9:1 then you really should not concider it with a stock lower end. Your dynamic cranking pressure is 129.94 PSI. I am running a Weiand 142 on a 350 crate engine and it gave t a real kick in the pants. Your dynamic compression ratio is 6.83:1. ( no computer controlled ignition, carb )įor the heck of it, I plugged in the numbers for an 元0 5.0LĮntering the calculated intake closing ABDC point for the '395' or ramjet camshaft ( not sure if there is advance ground in or not )Ĭamshaft, Rod Length, Boost and Altitude Correction to Compression Anyone used one? From what I have read, ideal max dynamic compression ratio would be 8.0-8.25, 8.5 borderline for a street engine on pump gas.

Compression ratio calculator sbc