I've heard these terms mentioned enough times before so I figured it was about time I asked the question - what do they mean exactly?!

Cheers,

Pete

i believe overrun is when you come off the gas at high revs, ie the engine is being pushed round with the throttle fully or partially closed Might be wrong though!

Overrun - When said of a vehicle engine: to slow down in response to a reverse torque transmitted through the gears from the wheels.

Overrun is when you come off the power and the wheels begin to slow the engine, ie the wheel speed is greater than the engine speed ie the wheels are over running the engine.

Coming off Cam - Camshafts are designed to produce the max power/torque at a particular rev range. to be off Cam is that your engine is reving below the the optimum revs for the camshaft, therefore not producing the maximum power (it really to do with the timing of the valves and the opening/closing times.. the duration)

Scott

'Coming off the cam' is normally used when talking about very 'peaky' full race cams. These often have power graphs that look like mount everest. You get massive power, but only over a very small band of revs, either side it drops off so quickly that if you get a gear change wrong you end up falling off the peak and losing most of your power, usually when you really need it.

Thanks guys, I thought that was what they meant (honest guv! )

Pete