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Old 04-11-2014, 09:47 PM   #74
Super73
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Join Date: Nov 2007
Location: Bay Area, Ca
Posts: 2,841
Re: Another 489bbc question

Sorry, if I was building a motor for a target RPM, the cam is the very last thing in the motor I would figure out not the first.

Stick a large duration/high overlap cam in a motor intended for high rpm, in a motor with a long runner dual plain and a small tube header, Peak TQ rpm is going to change from the large single plain / big tube header is should have. Those valve events are no longer optimal for that runner and header.

I have seen many combo's that the above example applies to. Big cam for high RPM yet choked off by intake and wrong headers. Power band is way earlier than initially thought. Or the opposite, small cam with a single plain and big tube headers, motor can't breath due to the small cam.

Valve events should always be figured out after all the supporting components are selected for intended usage.. As you said, the cam is the brains, if you don't go to school (supporting mods) how can you do your job (cam).

An optimal converter for best performance has to be selected once peak TQ RPM is identified. Otherwise you are only throwing darts.
__________________
------Motor---------------Bottle
60'---1.53---------------1.41
1/8---6.58 @ 105.92----5.87 @ 118.41
1/4---10.38 @ 126.97----9.24 @ 142.49
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