Will 340 HP manifolds fit 360 crate engine?

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migsBIG

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My first post in the tech section, so I hope this the right spot for it.

I have a 68' dart that I want to swap out to a v-8 from a slant 6. My problem is the exauxt. I have some 1968 HP 340 manifolds and the engine is a 400hp crate engine. DOes anybody know if I can use those ex manifolds on the magnum engine? I figure I might loose a little hp by not going with headers,but I want it to look as stock as possible under the hood. ANyone try this or are these and natural bolt on for it?
 
thanks for the info.

YOu wouldn't happen to have a guesimate on how much hp diffrence between the manifolds and say a set of nice doug headers? I plan on power steering and like the thought of the manifolds being away from the ps box unlike headers that have atendancy of cooking those a bit.
 
Not a for sure number....but I would guess the Doug's would be the way to go if you have the coin...Those things are nice!! But if you want to stay stock looking they will flow as good as you need a street engine to.
 
It's hard to say how much you will give up using manifolds vs a good header.
On a mild engine it will be little to nothing. On your 400hp, 360 it will be more.

On my 340 (fairly aggressive, high RPM build), I lost 13 mph and over 1 second in the 1/4 mile when I cut off my headers and went with 340 manifolds (other small changes were also made but most of the loss came from this exhaust change).
 
Wow, that's a big diff in exaust loss on the headers vs manifolds.

Might have to decide if the ease of mantiance/ stock look will be worth the hp loss.

Thanks again for the info there.
 
Wow, that's a big diff in exaust loss on the headers vs manifolds.

Might have to decide if the ease of mantiance/ stock look will be worth the hp loss.

Thanks again for the info there.

YOU CAN NOT GO BY MY LOSS!!!!!!!!!!


What I said is that the loss/gain will depend on the build.

My build was all high RPM (8000rpm shift point) so I lost a bunch because the manifolds would not flow there.

The posted link above comes up all the time…… It is also useless unless you are building a 300hp, 360 (or similar engine).
 
thanks for the correction. After reading the infomation from that article, I beleive my motor will do fine.

Thanks to everyone who got me on the right track.
 
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