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Old 07-09-2005, 09:53 PM
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what size exhaust


i have a newly rebuilt 350 bored .40 over, 268 lunati voodoo cam with matching lifters, springs, locks, and retainers, , h345np hyperuetectic pistons, 76cc cylinder heads, stock rods, and reground crank ( i don't think that matters), and a double roller timing chain, the specs on the cam are duration at .050 .227/233, the advertised duration is 268/276 the lift is .489/.504 the lobe seperation is 110 and the lobe centerline is 106 , hopefully i will be getting a performer rpm intake manifold, and a 650 holley double pumper, hopefully soon i will bump up the compression to 10:1 and get better flowing heads, anyways what size exhaust should i get, 3" or 2.5" it will be duals going into force mufflers, turned down before the rearend, or i might get it going out in front of the rear tires, it has headers on it also

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Old 07-09-2005, 10:39 PM
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2.5" should do fine little more backpressure out of it will provided better scavanging too IMO

Regards Mike
77 Z28 496 9 inch
10.23 @ 129
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Old 07-09-2005, 10:39 PM
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You have a very similar engine setup to what I have, and I have a mandrel bent 3" single exhaust (it does wrap over the rear end), with 1-5/8" shorty headers. It goes into a single Pro-Flo muffler (I think this sounds awesome, better than the hollow sounding Flowmasters), and it has dual 2.5" outlets. This setup seems to work great for my engine, as it makes good launching torque and still breathes good at high RPM. If you wanted to go to a dual setup I would go with 2-1/2" pipes, if you want a single exhaust, then go 3". Make sure it is mandrel bent to avoid restrictions, and if you get it installed by a muffler shop, watch very closely what they do when they wrap it around the rear end (if you end up doing this) - don't let them "cheat" and pinch it off, like they initially did to mine!
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Old 07-10-2005, 11:03 AM
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You should be great if you went with dual 2.5 inch pipes
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Old 07-10-2005, 11:28 AM
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I am making tons of power with 2.5" exhausts on my 11:1 400 with Sportsman II heads and a decent cam.

It is better to err to the small side.
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