2.5" or 3" exhaust?

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2.5" or 3" exhaust?

Post  Hangman on July 5th 2013, 11:14 pm

I'm at kind of a road block and need your input guys.

Getting ready to do the exhaust on my project truck ('81 F100 w/460) and need a little advise. Currently the engine is a '77 460 out of a LTD. Updates are: Weiand Stealth intake, Cam timing straight up, Edelbrock 800 carb, D5TE exhaust manifolds. Now, in the future, the truck is getting a fresh engine (this one is just to hold me over for the build without emptying my wallet completely). It will consist of a pair of C8VE heads, 2.19 and 1.76 valves, between 9.5 and 10:1 compression (has to run on premium or less pump gas), truck rods, same intake, carb, exhaust manifolds and such.

The manifolds will accept 2.5" pipe, but I don't have anything to do that size. I have all kinds of 3" stainless tubing (polished inside and out), mandrel bends, 3" stainless mufflers. I can always pick up all the 2.5" tubing I need if that's the best route.

Which is going to be the better tubing size for BOTH engines?
Is the 2.5" going to flow enough?
If you think I should run the 3", how far away from the manifolds should I put the adapters to go from 2.5 to 3"?

This is only a street truck and will probably never see over 5500 rpms, so I'm not worried about really revving it.

Any help would be greatly appreciated.

Dave

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Re: 2.5" or 3" exhaust?

Post  cletus66 on July 6th 2013, 2:31 am

Go big or go home. LOL. Step it up where the headers you will eventually use come to an end. Twisted Evil 
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Re: 2.5" or 3" exhaust?

Post  dfree383 on July 6th 2013, 2:43 am

Spend the money on some headers and use the 3" tube, its well worth the upgrade over manifolds.
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Re: 2.5" or 3" exhaust?

Post  Hangman on July 6th 2013, 12:13 pm

Those were the responses I kind of expected.  Thanks for the push in the right direction. Save money on the tubing, build some headers.

Thanks guys! Very Happy

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