cam overlaping

[motohd66]

i know its reccomended to slot the intake cam sprocket to get the cam timing overlaped a bit on a turbo but i was wondering if anyone has tried this on a non turbo/supercharged apex. i was just wondering if it was worth the time?
thanks
brent

 

[TWIN TURBO]

Don't quite know if you have an full understanding of the cam timing changes being made on the turbo applications. The object of the game with turbo engine is to REDUCE the overlap. Overlap meaning the time in degree's where the exhaust valve is closing and the intake valve is opening. Turbo's tend to create back pressure in the exhaust and if both valve's are open at the same time when the piston is at TDC you could have exhaust moving back in the cylinder and up the intake track. To minimze that from happening you spread the lobe centers and reduce the amount of time in degree's when both valve's are open.
Now very generaly speaking, to answer your question, Spreading lobe centers, reducing overlap, tends to flatten the power band at the expense of reducing peak power. I don't see a reason to do this in a non-turbocharged/supercharged engine without specific knowledge of a need for it. A racing engine with a proper exhaust system can benefit from valve overlap as the exhaust pulls fresh charge into the cylinder. If your not turbocharging leave it alone.

 

[motohd66]

hey thanks! thats exactly what i was looking for in a answer, i just remember hauck selling sloted cam sprockets for a rx-1 and i was wondering if it applied to an apex as well, all though im sure it didnt gain much on the rx. thanks again!

 

[shiznitt]

have ran into a couple of guys that have sloted the cams on a head shim install and they claim that after a few runs it slips back to original position, just what i have been told. if you are not s/c or turbo, do not take apart