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Exactly how does a performance camshaft perform better giving more horsepower?
Without going to deep into camdesign semantics I suggest the following, in general:
1 Let's name the area limited by; outer dia of the valve x the valve lift, the "flow-window" or flow curtain"
2 The larger this flowarea at max lift the larger the POSSIBLE flow from a specific cam. This improves generally the overall performance.
3 Larger flowarea can also be gained by letting the valve stay open longer (=duration). This does usually improve the torquecurve in the upper rpm and consequently less torque in lower rpm...
If higher airflow is possible the combustionpressure = torque = bhp might be higher and/or fall less in upper rpm, if the set-up is properly.
This improves the performance
A little more advanced definition of camshaft function could be as follows:
The cam area is the area beneath the valvelift curve and above the clearanceline.
This area, which is directly correlated to the possible flow a certain cam might allow, is possible to enlarge in a few ways:
1 More valvelift, no real disadvantages...
2 Higer valve accelerationrate/deceleration, more strain
3 More valveopening time, duration, lifts the performance upwards and weakens the lower range...
Then ther is another area, the overlap:
The overlap, and corresponding overlap area, decides how high up in the rpm the flow might continue; with a lot overlaparea the engine is weaker in bottom rpm and, yes, stronger up, and with less overlaparea the opposite.!
N.B. The engine might utilize higher flowrate out of a camreplacement ONLY if the rest of the flowsystem (from the airfilter to the exhaust tailpipe end...) allows it, in general...
BR
M.Aaro
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