Cam and compression ratio compatibility
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| + | ==The following is for fellows who know nothing about engines== | ||
| + | You do not match characteristics of camshafts. You design the camshaft to create the performance characteristics you desire from your engine components. The following are as they describe it, "only rules of thumb", "ballpark figures", "a little more" or "a little less", a "starting point" and "nowhere near scientific or definite in it's scope". If you are interested in the facts about selecting the proper camshaft, you can receive the facts and mathematics on the internet from Controlled Induction Software. | ||
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==Matching cam to compression ratio== | ==Matching cam to compression ratio== | ||
Sometimes it's difficult trying to explain to fellows who are new to hot rodding that you have to match the characteristics of the camshaft to the static compression ratio of the motor along with the operating range where the cam makes power. The camshaft is not a stand-alone piece. It must be coordinated with other motor and drivetrain parts in order to arrive at a combination of parts that will all work together toward a common goal. | Sometimes it's difficult trying to explain to fellows who are new to hot rodding that you have to match the characteristics of the camshaft to the static compression ratio of the motor along with the operating range where the cam makes power. The camshaft is not a stand-alone piece. It must be coordinated with other motor and drivetrain parts in order to arrive at a combination of parts that will all work together toward a common goal. | ||
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| + | ==STOP RIGHT HERE, THIS IS INCORRECT== | ||
| + | What size stroke is in these engines that these figures above are suppose to represent. You can't believe that an engine with a 3.000" stroke is going to have the same RPM range as an engine with a 4.500" stroke, using the same duration cam? It won't and all of these generalizations are ridiculous. The duration of a camshaft is determined by the Mean Port Velocity and the Mean Piston Velocity, which is determined by the Stroke and RPM. You're trying to fill the cylinder at a given RPM, and in order to due that you need to control the Mean Port Velocity during the induction process. Controlled Induction! Compression does not have anything to do with determining the correct cam duration for your engine and desired Peak HP RPM? | ||
| + | ((Mean Piston Velocity FPM / Mean Port Velocity FPM) * PI), and 2 more calculations give you the valve seat duration. You can find it in Controlled Induction. | ||
==Additional reading/engine theory== | ==Additional reading/engine theory== | ||
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