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Old 06-20-2007, 08:39 PM
PTAddict PTAddict is offline
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This is definitely a more aggressive cam, and will easily put you into low/mid 500s in HP with fully ported Track 1s. It's going to idle fairly lumpy, but will still be streetable. Since you're using a manual trans, you can bump the idle speed up if you want less idle shake and crisper off-idle throttle response.

IMO, there's no need to go to a 1.6 rocker on the exhaust. Extra high exhaust lift on a normally aspirated motor usually doesn't produce more power to speak of - it's the intake side which benefits more from extra lift, due to the larger diameter of the intake valve requiring more lift to max out the port flow.

Sounds like a fun motor. Enjoy.
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Old 06-20-2007, 11:15 PM
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tyoneal tyoneal is offline
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PTaddict

Thanks for the information.

I was concerned that not keeping the ratios of lift the same, that it might not run as well as it should.

Is there a lot of slack in the specifications numbers of a Cam where performance doesn't degrade if it is not run or cut according to a specific set of numbers?

Thanks,

Ty
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Old 06-21-2007, 05:23 PM
PTAddict PTAddict is offline
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Quote:
Originally Posted by tyoneal
PTaddict

Is there a lot of slack in the specifications numbers of a Cam where performance doesn't degrade if it is not run or cut according to a specific set of numbers?
Basically, yes. The most important specs of a cam are actually the "valve events" - the opening and closing points of intake and exhaust valves. The optimum valve events for a given application depend on a bunch of parameters - port efficiency, valve size, intake runner length, cross section, and taper, compression ratio, header specs, and then desired operating parameters like peak power RPM, idle quality, etc, to name just some of them. Any off-the-shelf cam will only be a rough approximation of the "ideal" valve events, and variances from the specs of that cam may improve or degrade performance.

Cams for OEM engines these days start out as quite precise optimizations from very advanced engine simulation software, with final refinement in real world dyno testing. As performance enthusiasts, we don't have access to these kinds of simulation resources, so we have to rely more on advice from cam manufacturers and fellow enthusiasts. But nobody - not Crower, and for sure not me, can tell you for sure the "perfect" specs for your cam. Fortunately, you can still get very good results by being "close enough".
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Old 06-21-2007, 10:32 PM
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tyoneal tyoneal is offline
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Quote:
Originally Posted by PTAddict
Basically, yes. The most important specs of a cam are actually the "valve events" - the opening and closing points of intake and exhaust valves. The optimum valve events for a given application depend on a bunch of parameters - port efficiency, valve size, intake runner length, cross section, and taper, compression ratio, header specs, and then desired operating parameters like peak power RPM, idle quality, etc, to name just some of them. Any off-the-shelf cam will only be a rough approximation of the "ideal" valve events, and variances from the specs of that cam may improve or degrade performance.

Cams for OEM engines these days start out as quite precise optimizations from very advanced engine simulation software, with final refinement in real world dyno testing. As performance enthusiasts, we don't have access to these kinds of simulation resources, so we have to rely more on advice from cam manufacturers and fellow enthusiasts. But nobody - not Crower, and for sure not me, can tell you for sure the "perfect" specs for your cam. Fortunately, you can still get very good results by being "close enough".
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PTaddict:

Thanks for your explanation. It is clear now. I appreciate you taking the time to educate me.

Ty
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