[Hugh Keir]

Are camshaft ramp rates the same for the rise and fall of the valve?

I have not seen ramp rates quoted, but can recall a conversation many years ago with the engineer that developed the Metro 6R4 engine for BL Motorsport, where they spent some considerable time trying on the engine dyno trying to sort out the best compromise on lift, duration and ramp angle.

As a check at what they thought was the end of the process, they asked for a set of Cosworth profiles to be ground on to some blanks and the engine torque and power jumped noticeably.

There is also nothing that I can think of that would suggest the need for the angles to be the same, although they generally do.

 

[R32 Combat]

I have not seen ramp rates quoted, but can recall a conversation many years ago with the engineer that developed the Metro 6R4 engine for BL Motorsport, where they spent some considerable time trying on the engine dyno trying to sort out the best compromise on lift, duration and ramp angle.

As a check at what they thought was the end of the process, they asked for a set of Cosworth profiles to be ground on to some blanks and the engine torque and power jumped noticeably.

There is also nothing that I can think of that would suggest the need for the angles to be the same, although they generally do.

If the angles are the same, then are you sure the steeper the ramp rate the more torque is required to turn the camshaft?

 

[Hugh Keir]

If the angles are the same, then are you sure the steeper the ramp rate the more torque is required to turn the camshaft?

Yup, as you increase the camshaft ramp angle you will increase the speed that the valve opens and therefore the work being done while the valve is opening, so inevitably increasing the torque required to turn the cam.

Bit like walking up a steep hill compared to walking up a gentle slope hill

 

[R32 Combat]

Yup, as you increase the camshaft ramp angle you will increase the speed that the valve opens and therefore the work being done while the valve is opening, so inevitably increasing the torque required to turn the cam.

Bit like walking up a steep hill compared to walking up a gentle slope hill

This is counter acted completely by the valve pushing the cam lobe up?

 

[Hugh Keir]

This is counter acted completely by the valve pushing the cam lobe up?

So you think it takes the the same effort to open the valve slowly or quickly?

 

[CSB]

Can a well timed 272 beat a 260 lower down the curve?

 

[R32 Combat]

Steeper ramp would require more effort I would think.