What Gives a Cam that "Pull" Power?
12-28-2007, 01:26 AM
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What Gives a Cam that "Pull" Power? Just curious, i know that certain cams are ranged at certain power bands, but i'm just wondering what exactly causes it to "yank" at that certain RPM and up. I mean, is there a magical threshold that once it reaches that, magic happens in the block. I'm engine illiterate, i was hoping someone could enlighten me.
12-28-2007, 01:55 AM
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If the car is set up right this isnt a concern anyway, but I think it's caused by too much duration for a given # of cubes. That yanking rpm point is the cam just beginning to work effectively.
12-28-2007, 04:13 AM
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Basicly air/fuel can only move so fast into and out of the cylinders. This isn't a problem at low rpms but at high rpms everything is moving too fast for the air to get in and out of the cylinder. Agressive duration cams will open the valves early and leave them open longer to let the air have more time to get into/out of the cylinder at high rpms but at low rpms the air can just pass right through and effective compression won't be happening until later because the valve is open later when the piston is coming back up. Which is simply put why cams have different rpm ranges that they were designed to make power and is why bigger isn't always better.