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Old 04-16-2010, 04:43 AM
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Quote:
Originally Posted by crussell85
The thoughts that I am having is that I need less duration because I am holding the intake and exhaust valve open together to long and am dumping raw fuel out the exhaust.
From what I have researched and read this is the cam (08-465-8) I came up with http://www.compcams.com/Cam_Specs/Ca...?csid=206&sb=0
It is also one that comp cams recommends in their cam selection software. I ran it on my Desktop Dyno and it is showing a great amount of improvement. I was just wanting some feedback or a straight up yes or no before I would commit to buy.
What you're running into w/the cam you've selected, is a cam w/"short" duration and basically no overlap in combination w/a static CR of over 10:1 being too high of a 'dynamic' CR. There will be enough "efficiency" of the small cam to actually cause the 10:1-10.5:1 CR (or whatever it is, exactly) to cause detonation. When that happens, power takes a nose dive and parts breakage will happen.

You need to lower the static CR, OR choose a larger cam, duration/overlap-wise and the gears and torque converter to make it all work together.

The cam Comp spec'ed for you presumably has specs that will allow your CR to be compatible w/the cam and the rest of your combination of parts and gear ratios. It would be a better choice, IMO than the cam you picked. Is there a reason for not going with Comp's recommendation?

Here are the specs, from them you can see how the cam Comp suggested will not have as high of a DCR as the "little" cam you picked for yourself.

252XFI HR13 #08-464-8
Intake open 17BTDC close 55ABDC
Exhaust open 69 BBDC close 15ATDC

Comp's choice: XR269HR #08-502-8
Intake open 26BTDC close 62ABDC
Exhaust open 74 BBDC close 22ATDC

I hope this helps you, and doesn't just confuse the issue more.

Good luck.
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