Is 3" exhaust overkill on a 5-600 hp 440 six-pack motor?

[Grec]

My goals for my 440 six-pack are, currently, 500-600 hp. Mildly tweaked.

Would a 3" exhaust set-up be overkill?

I'm assuming the 2" factory size would be too restrictive but am wondering if a 2.5 would do the trick.

I don't want to run into back-pressure/loss of torque issues.

Also, I plan on running stock exhaust manifolds to keep the engine bay nice and factory looking so that may be a bottle neck right there.

Not sure...

[Chryco Psycho]

with stock manifolds I would use 2.5" TTi mandrel bent pipe & use a cam with a 112* centerline to maximize the efficiency of the iron manifoldsI built a 440 6 Pack last year that looks bone stock with a custom cam & ported heads & it pulled 525 gross HP so about 130 more then stock with ease

[moper]

Stock manifolds wont support 600hp unless it's from 540 cubic inches...lol. The manifolds are teh cork, but I owuld go 3" anyway. I like loud aggressive exh notes tho. Really, headers and 3" would be a "must have" for over 500hp. But like CP said, the right cam, the right package, you can make more.

[Grec]

Ugh.

That's what I was thinking; that the manifolds would be a real bottleneck.

Tough call...

Thanks guys.

[72hemi]

I've heard of people extrude honing manifolds to increase flow, and 3 inch exhaust may sound cool, but I think it will hurt you, I'd go 2.5 inch.

[nivvy]

I would go 3" just because it looks cool....

[moper]

...and sounds badaz

[Moparal]

I ran 3 inch and flow masters on my 72 cuda for a few years before I went full out race car with it.  I had good results from it being this combo here, but I used headers to go 11.85

9.0/1 comp  355  8 3/4    4500 turbo action 9 inch  self ported 906 heads  hooker 2" headers  3" flow masters and 3" pipes. My car weighed 3780 lbs and I run a comp 555 solid and L 60 mickey super soft. Street car only. 850 4781 holley, 1/2 fuel line and sump in my tank, 8 springs lft, 9 rt. I made them myself too. The car 60 ft  1.51 in street trim. 

I had less hp then you will have, so it depends on the combo

Remember that if you are makeing a 5-600 hp engine for the street, don't forget the safety equipment. It can save your life....  Drive shaft loop, 3" rear studs, trans shield or blanket, sfi balancer, fire ext, Even street cars need this minimum if not more when makeing power.   Have fun and be safe

[JS29U]

   If you are going to use hp manifolds, read up on Andy Finkinbaumer, writer for popular hotrodding , car craft, etc and regular on moparts.  His 470 ehead, dual plane, 800 edelbrock, 528 mp cam and hp manifolds put out 550 hp and 470 r whl hp.  The key with hp man. is keeping overlap and duration down. His dyno results are on comp cams web site. They couldnt beat the 528 with bigger cams. And that was with comp cams helping out.  HP man. dont like much more than 60 degrees  overlap.

   Pontiac guru Jim Hand job proved that you dont need big tailpipes. The air is cooled out back and doesnt expand as much.  He found 3inch into a 2 1/2 x pipe was best with mufflers back as far as possible, like e bodies.

   Andy uses 3 inch pipes front pipes with 2 1/2 exhaust.

   The more hp u have, the more the manifolds will cost u.

   Get real wild, then u need 4 inch. My crane with 94 overlap ran like crap with factory mufflers.

[Grec]

Thanks, guys.

Alot to think about.

I guess the 1st decision is going to be whether or not to run those HP manifolds as it sounds like I'm going to be sacrificing quite a bit just to keep a factory look...

Does it really matter when doing a 440-6 in a '73 Challenger? No, not really.

But for some reason I think it would be pretty cool to have this thing set up like a factory car.

A 1-of-none! :-)

Heh. It'll probably come down to flipping a coin.

[todd383]

No, it wont be over kill, just installed a tti 3"  He already has 17/8 headers on it,  onto a friends 440 challenger. (it had a 21/2 system on it) it made the biggest difference in the world!!!! we used the x-pipe. I think he made 25 more RWHP. and sounds a hell of alot better