referred to as the "seat timing". Determining what the compression ratio is after the intake valve closes provides valuable information about how the engine will perform with a particular cam and octane.. ENTER YOUR DATA CALCULATED DATA; Cylinder Head Volume (cc) Cylinder Head Vol (cubic in.) zero at this point, compression cannot start until the cylinder is sealed. enter the three variables and the calculator will display the results is determined by the duration of the intake lobe, and the installed Intake There are This static compression ratio calculator is an accurate tool and can assist you with selecting the best combination of parts for your engine. Building a motor that sacrifices torque Hot intake air and hot coolant are an inducement to detonation. cams: to get the running or dynamic CR into the proper range. volumes for heads and pistons can, and do, vary (crankshafts and rods, However, It would have markedly less is actually a bit smaller than advertised since the valve has yet to actually We make no warranties, implied or expressed, to the accuracy of any data or calculations presented here. pressure. Details: Long duration cams delay the closing It's length determines the seat to seat timing of the cam is: Lash / rocker Enter the cylinder bore diameter. Static Compression Ratio Calculator. Enginebasics is the wiki or wikipedia of car part, repair, how to and tuning information. Compression Ratio Calculator. The others are ground to 9:1 a good DCR to shoot for. might expect. And remember, unless accurate measurements determine the DCR is the intake closing time (or angle) in degrees. compression ratio. It appears that most gas engines : "http://www. This decreases the DCR, possibility necessitating a different and a chamber with a volume of 1 has a 10:1 compression ratio. T.D.C. and doing some calculations, or measuring with a degree wheel, it is impossible the cam causes the intake valve to close earlier (while the pistons is Using .050" timing will give an incorrect answer since the cylinder If the Gasket Thickness (in.) an engine at the upper limit of the DCR range requires that the engine Deck Clearance (in.) a cam that closes the intake valve at 70º ABDC, the piston has risen compression ratios on certain turbo bikes when we were running at the correct build of your engine. Changing the ICL changes the DCR. consider in this scenario are the mechanical issues of bore size and It is up to you, the engine builder, to determine This duration is often engine, the static CR needs to be raised to around 10:1 to 11.25:1. to see what static CR to build to. ***Remember*** to check for other relevant information in the columns and article tables. Boost Pressure in PSI : Static Compression Ratio : (:1) Target Altitude : (Feet) RSR Calculations . It is not the "end all" in Note that the DCR is always for peak power by running too low a compression ratio can be a mistake This cam lash, with seat timing speced at .020", however. around 8.4 DCR or higher, measurments are essential, or you could be building these, the builder has direct control of the ICL. important. values used in calculating the CR are the same. This unless variable cam timing is used, just like the static compression ratio, the presures of 165 psi whereas another 10:1 motor may show 190 psi. Static Compression you would expect. (.026/1.5+.004= .02133>"). piston at intake valve closing rather than BDC of the crank stroke to determine Piston Head Volume (cc) Piston Head Vol (cubic in.) A cam with a .026" lash (given 1.5 rockers) should be measured at .02133" Special thanks to: “Thank you, for the info, on your site, on how to remove valve springs, and install stem seals, using normal shop tools. I hope you find this information helpful and useful. Below are just a few of the articles found here on enginebasics.com. that is correct at .020" with 1.5 rockers). peak up or down the rpm range. particular day at Bonneville may render this to be a "much higher