HP exhaust manifolds

[Terry Hauck]

I am building an RV 440 for my 69 Roadrunner. It will be a mild street build with about 10.5 comp, 509 cam, 906 heads. Because of starter and power steering header clearance I am thinking of using my stock HP exhaust manifolds. Thoughts and suggestions please. Thanks

 

[Russ69Runner]

Those should be fine. Watched a video of a guy who tested header's then the HP original manifold's and the HP's made more House power. Would use 2 1/2 exhaust pipes going out the back form the Manifold's. Dual's of course.

 

[Russ69Runner]

Terry that was Nick's garage surf him on the net.

 

[ACME A12]

The F.A.S.T. Racing guys run 10's with manifolds so....

 

[69hemibeep]

The F.A.S.T. Racing guys run 10's with manifolds so....

Those have been worked over just a bit LOL

 

[Russ69Runner]

So what do they do with them as far as worked over 69hemibeep.

 

[ACME A12]

They are extrude honed (Abrasive Flow Machining).

 

[Terry Hauck]

I watched that episode of Nick's Garage. He compared HP manifolds, Max Wedge manifolds and Hooker Headers. The headers were #1, Max Wedge #2 and the HPs were last. Headers and max wedge were close like 5 horses but the HPs lost 50. I might have to rethink my plan. Another thing is my headers are Doug's 1 3/4 for a 383. Probably should go with 1 7/8 with a 440. Comments please.

 

[quikbird]

1 7\8 will work fine. They also acid dip the internals of the stock headers as well to thin them from the inside in f.a.s.t. Class.

 

[Lil 383]

It’s gone 11.45 @ 119.9 after this. Only work done to the manifolds was port match and heat riser flapper removal.

 

[69hemibeep]

The more flow the more restrictive they become IE built motor or cubic inches. That being said I avoid headers on mild street builds just added maintenance.

 

[Terry Hauck]

A lot more clearance too. I had to use a high torque mini starter and still had to dent in the #1 tube. Doug's headers do not fit like a glove.