In the automotive world, where the engines are all of 3 or more cylinders, the best use of such testing is not to measure for a specific number as much as to test for excessive variations cylinder to cylinder. 100 PSI A healthy engine should have 100 PSI per cylinder. Lol. I bought a truck with a built shortblock in it back in August and just got it back from Rhodes Custom Auto after having a roll bar installed. Conventional compression testing is not a particularly accurate measure of either engine health or compression ratio. I have the dual plane stealth intake. I'm no more than 5psi difference in all 8 cylinders. And m carb is way to small. much cyl pressure will todays pump gas We use data about you for a number of purposes explained in the links below. Use this calculator to see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio. I make sure no kids or anyone else is near the vehicle! Looks like I have alot to research. No doubt, I am very familiar with that combo though. For a good example, two of my most recent motors were measured at 190 PSI and 210 PSI. How to convert a compression ratio to PSI - Quora Please support our sponsors and let them know you heard about their products on Cruisers Forums. http://www.gregsengine.com/cylinder-compression-testing.html I bet your compression comes up when done this way. So a 10:1 ratio yields 147psi. Or bored over or the exact timing of the cam to ensure its advanced 4*. google_ad_type = "text_image"; 7.0 to 1 = 140 psi 8.0 to 1 = 160 psi 9.0 to 1 = 180 psi 10.0 to 1 = 200 psi etc. so compressive heating is a variable in cranking pressure. It may not display this or other websites correctly. The static compression ratio is approximately 10.94:1, intake valve closes about 60 degrees after bottom dead center and compression pressure is 190 PSI. Multiplying the low-speed effective compression ratio of 7.32:1 x 14.7 would yield a compression pressure of 108.84 The engine sounds different to me on 87 octane so I run it on 93. You can't directly convert cylinder cranking pressure to static compression ratio. You could have 20:1 static compression and close the intake valve at 90 ABDC to get really low cranking pressure. You can approximate it with dynamic compression ratio. If you don't have a leak tester, you can squirt a little, Powered by vBulletin Version 3.8.8 Beta 1. First the compression ratio is the comparison of the cylinder volume when the piton is all the way down (bottom dead center, BDC) (maximum) and when the piston I never questioned him but alot of people have said I'd benefit from a 850. So if you 770 street avenger. Ill see what options I have for the distributor I have. That means that the engine is giving more push on the piston, and more torque is generated. Cranking pressure vs Compression Ratio - ThumperTalk