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Duration/Lift : Power Guideline on RB26.

25K views 26 replies 11 participants last post by  R32 Combat 
Anyone got an answer to this? More torque on 272?
Increased duration cams require higher revs to deliver their maximum power.

There is also the ramp angle on the cam to consider, greater angle means higher loads to turn the cam.

Higher lift cams will deliver more power at a slightly higher RPM compared to their lower lift family assuming the same ramp angle.

Titanium buckets reduce the mass of the valve that has to be opened, so can be opened faster using an increased ramp angle.

Cams are designed so that they can be used with a specific mass of valve, spring, retainers etc at up to a safe working RPM.

Pretty hard to nail down what you want.

Tomei manufacture and sell great cams with matching valves and springs with titanium followers for the higher lift.

Tomei manufacture cams for a number of the Japanese suppliers, great quality and hard to beat.
 
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.
 
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
 
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