Mopar exhaust

[1970340t/a]

hey guys i have a 340 with exhaust manifolds from a 318 and i was wondering what is the biggest pipe i can run with these exhaust manifolds?

[peg leg]

Measure the ID of the outlet. You can neck up bigger after that. Chances are it's 1 3/4 or 2.0

[DonCarr]

I think the limit on pipe diameter has more to do with road clearance than manifold size. You may want to allow for the future installation of headers, 2-1/2 should do that.

[passing you]

I'm with don, neck it down to 2 1/2 for headers in the future.

[TeamDart]

You could go as big as you want technically... But I wouldn't go over 2 1/2" Myself.... A good combination for "stocker" or very mild motors I've tried on a few, is 2" Going into the muffler, and 2 1/2" comming out... Nice deep growl without the Gloggyness of going too big

[Tarrbabe]

Have been to step headers. This allows for the resistance of the exhaust flow to grow less as the length extends. The idea is to have a free flowing exhaust system to increase the flow. 2 1/2 sounds good to me.

[DonCarr]

David Vizard puts a good dual 2-1/2" system as up to 375 HP before power loss begins. That would be with mandrel bends and appropriate mufflers. That's an easy number to reach for a 340 with headers. Cheaper bends and mufflers would drop that number.

Vizard says he's never lost any power with an H-pipe or X-pipe and often gains up to 12 HP while dropping noise a bit. 20-40 HP gains are possible with proper collectors, termination mufflers and h/x -pipe, over straight duals.

Sounds like 2-1/2 pipe with cheap bends would be perfect for stock manifolds and mild engine, but may drop a few HP in header use.

Hint - Magnum truck manifolds are rear dump, look cool, flow better and fit e-bodies, may nick steering box (grind box a bit or angle mill manifold ?)

[BELVEDERE2]

Originally Posted by DonCarr

Hint - Magnum truck manifolds are rear dump, look cool, flow better and fit e-bodies, may nick steering box (grind box a bit or angle mill manifold ?)

If you're stuck on using manifolds I would go this route. Can't say I would want to run 318 manifolds on my 340. And I'd bet there is a ton of 360 manifolds just waiting to be picked up for cheap.