I'm hoping and engine builder has actually measured. Do the specs of a solid roller camshaft take into consideration the suggested valve lash? If the duration at 50 is 236 at the lobe what would the duration at the valve be, more or less than that of a hydraulic roller. If one had two camshafts, one a hydraulic roller and one a solid roller with the same duration lift etc. and tested with mechanical rollers on both, would the hydraulic roller cam have more or less duration at the valve than the mechanical roller cam?
If one had a hydraulic roller with a duration of 236 what size solid camshaft would be needed to get the same at the valve duration?
Anyone know for sure? I've heard many opinions all conflicting. thanks
The solid cams specs do not take lash into consideration when advertising duration. Thus if it said 236 in duration, that is without lash deductions. You lose duration with the lash for sure. That is why a solid cam is normally longer in duration to be equivalent to a hydraulic cams duration..
Thank you for that reply. The reason I ask is one cam supplier told me one thing and another told me just the opposite. I'd like to know if anyone has actually taken a hydraulic roller and a mechanical roller camshaft with the same duration and lift specs, installed them in the same block and tested the said specs.
I believe the Engine masters has done that test with a chevy engine. Check out https://youtu.be/8UaXhfbAMF0 Really interesting results. Bottom line, the hydraulic roller makes a little less power but still preferable to a solid for street use.
Thanks for that, not really what I was looking for but interesting. I think one would expect more top end power with a solid over a hydraulic on same spec camshaft.
I did find a test that was done on a spintron machine where the lift at the valve could be measured with the engine being turned over with the spintron. A hydraulic roller with a lobe duration at 50 of 230 had an at the valve duration of 243 with zero lash and an at the valve duration of 240 with 0.006 inches of lash [hydraulic cushion] . A solid roller with a 50 thou duration of 236 also had an at the valve duration of 243 with 12 thou lash and 241* with a valve lash of 16 thou. So to get the same at the valve duration, a solid roller had to have 236 degrees lobe duration compared to the hydraulic's 230 degrees lobe duration. So if I switch to a solid roller i'll have to add at least six degrees duration to get the comparable duration of the hydraulic roller.