Engine dyno software. Anything good on the Internet?
In cam manager you can set the advertised and .050 duration and it will calculate the acceleration rate. You can choose the lifter type as well. It will show the difference between the different types
A few people seem to be misunderstanding what I'm saying when i say that solid cams need more duration to make an "equal" power curve as a hydraulic camshaft in an otherwise identical engine.
In desktop dyno2003 changing from hydraulic to solid lifter (and leaving all other cam/engine specs the same. eg, adv duration, 0.050" duration, lift, lobe separation) does absolutely nothing to the simulated output when in reality it would dramatically lessen duration and overlap at the valve due to several crank degrees of cam duration being taken up by lash, creating an earlier power curve / less power at high RPM and more at low RPM.
Picture two engines side by side with identical camshafts. one has adjustable rockers and the other doesn't.
The one with adjustable rockers has .020" of valve lash. This means the LIFTERS move up about .014" before the valve begins to move. (0.014" x 1.5 rocker ratio = .021" lash. there's some loss from geometry there so 0.014" is probably a conservative example)
It takes several degrees of crank rotation to make the lifter move .014". 10 degrees seems to be a good number to work with.
When you rotate both motors at the same speed, the valves will start moving earlier and finish moving later on the one with zero lash. (like a hydraulic lifter) IE, spend more time open.
The one with 0.020" valve lash will start moving the valve later and finish earlier. IE spend less time OPEN
This need for valve lash makes the cam "seem" smaller, even though the cams are both identical, the valvetrain makes the motor respond completely differently.
But not in dyno2003. And that's a big oversight if you ask me.
Ramp rate doesn't really have anything to do with what I'm talking about. But it too remains unchanged when you switch from hyd lifter to a solid in Dyno2003.
Ramp rate is typically more reliable and accurate when the two points of reference are taken at .050" and .200" because they are standardized and not open to interpretation. Advertised duration is the one where every manufacturer chooses for themself when a tappet has begun to rise or finished falling. ie. 0.001? or 0.006? (nobody uses 0.001" just saying)