HP exhaust manifold verses Header comparison

[Kern Dog]

You can swim pretty fast with your shoes on but would be faster without them.
In every instance of an engine with any hint of high performance, Headers increase power. You would have to be a real idiot to look at a cast iron manifold sitting next to a header and NOT see why.
The volume is only part of it; larger internal passages do free up the flow.
The collector helps draw out exhaust pulses as well.
A stock 383 or 440 will see an 18 HP gain, minimum.
Any engine with a bigger cam, bigger carburetor and better heads will absolutely love the headers compared to any exhaust manifold.

 

[strokie]

No problems...
I don't say headers don't make more power, but manifolds can make power too...

 

[Aeronet]

Maybe it should be said that you can make power even with manifolds.

 

[strokie]

My 1967 Dodge Charger 1/4 mile ET is 12.87 at 109.26 mph with manifolds...
Stock tires with 3.23 suregrip.
Personally I don't need headers...

 

[RemCharger]

All depends on the goal! If goal = 12.50s.... you might need headers!
Very nice car!

 

[BSB67]

All depends on the goal! If goal = 12.50s.... you might need headers!
Very nice car!

I think you meant 11.50

 

[Turboomni]

My 1967 Dodge Charger 1/4 mile ET is 12.87 at 109.26 mph with manifolds...
Stock tires with 3.23 suregrip.
Personally I don't need headers...

Absolutely Love it man!

 

[Turboomni]

Got my 505 being built and I am in MA. Haven't talked with him in a while and hope he is ok! Will call him this week. Got 2 sets of HP's in good shape.
One on my present 440 and a set for my 505. The Hp exhaust manifolds really hug the valve cover as you know or at least some of them. If you plane them flat and they get too close to the valve cover can you weld some meat to the exhaust manifold inlets and the plane them again for better clearance?

 

[strokie]

Got my 505 being built and I am in MA. Haven't talked with him in a while and hope he is ok! Will call him this week. Got 2 sets of HP's in good shape.
One on my present 440 and a set for my 505. The Hp exhaust manifolds really hug the valve cover as you know or at least some of them. If you plane them flat and they get too close to the valve cover can you weld some meat to the exhaust manifold inlets and the plane them again for better clearance?

Or may be make a steel plate to get some distance...

What will help, but it's a PITA (if you can fit them at all): 1" thick steel exhaust flange as a spacer between the manifolds and the head (with longer studs). If you can't water-jet etc. you could use 3 X 3/8" common flanges each side.
1. straighter path for gas leaving the port before the turn
2. more volume inside the casting
3. keeps the pulses separated longer before merge
Yes, 6" thick would be better, but...



Boffin Emeritus

 

[BSB67]

This runs 11.70's @ 120 with manifolds.

 

[Turboomni]

This runs 11.70's @ 120 with manifolds.

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Very nice! Got a link /pic and description of your car? Love to see and read about it.

 

[BSB67]

Thanks
Http://508charger.yolasite.com

67 specs

 

[PeteBell68]

Beautiful car love the stock look . Great time as well on the track

 

[Turboomni]

Thanks for posting that BSB67. If my 505 69 Fury build even approaches your time I will be extremely happy. I am using HP Manifolds and 3.23 rear also

 

[Turboomni]

May I ask a question here between HP and Torque. I saw a post that stated "HP you calculate and Torque you feel" I think he was speaking of street performance , not sure. In my case with the HP manifolds on my stroker ,it will make lots of torque from 3000 rpms to I guess 4500 rpms . Question is if I am at such a low rpm in my torque power band with my setup with HP manifolds and do not require huge high rpm airflow will I be in a better place with the manifolds than with full flow headers?? Rpm limit I think will be 5500.

 

[BSB67]

May I ask a question here between HP and Torque. I saw a post that stated "HP you calculate and Torque you feel" I think he was speaking of street performance , not sure. In my case with the HP manifolds on my stroker ,it will make lots of torque from 3000 rpms to I guess 4500 rpms . Question is if I am at such a low rpm in my torque power band with my setup with HP manifolds and do not require huge high rpm airflow will I be in a better place with the manifolds than with full flow headers?? Rpm limit I think will be 5500.

No. It's a matter of what happens when both the intake and exhaust valves are open at the same time, and not that much of a function of rpm itself, although will become worse. You will make more torque with the headers, even at lower rpm.

 

[Bee1971]

WI Snowmobiling

Speed = How fast you can get to the bars while staying on the trails

Torque = How many trees you take out once you leave the trails after the bars

 

[RJRENTON]

IMO....
Continuing the header vs factory HP manifold controversy....one of the absolute best set of factory HP manifolds I've ever sern was on the Max Wedge cars... 4 into 2 into one EQUAL LENGTH CAST IRON MANIFOLDS with the removable caps on the manifold outlet pipes......extremely rare but extremely well designed and ABSOLUTELY and Totally cool looking. I've only witnessed 2 different cars with this option...a 1964 Plymouth Savoy and a Dodge 2 dr sedan.....sure beats anything currently offered....

I think that only 30-40 sets were ever profuced. They were relatively heavy @ ~ 40#, compared to tubular headers.....
BOB RENTON

 

[BSB67]

Certainly the FAST and PSMCDR class has put a light on the performance potential hierachy of the the factory offerings. The Max wedge manifolds are up there, but the Hemi is still on top for team Mopar.

 

[GOLDMYN]

IMO....
Continuing the header vs factory HP manifold controversy....one of the absolute best set of factory HP manifolds I've ever sern was on the Max Wedge cars... 4 into 2 into one EQUAL LENGTH CAST IRON MANIFOLDS with the removable caps on the manifold outlet pipes......extremely rare but extremely well designed and ABSOLUTELY and Totally cool looking. I've only witnessed 2 different cars with this option...a 1964 Plymouth Savoy and a Dodge 2 dr sedan.....sure beats anything currently offered....

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I think that only 30-40 sets were ever profuced. They were relatively heavy @ ~ 40#, compared to tubular headers.....
BOB RENTON

NOT NOW https://www.ebay.com/itm/Mopar-62-6...666440?hash=item54895a8f88:g:440AAMXQMmJRMW2x