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HP exhaust manifold verses Header comparison

62440

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Merry Christmas Everyone, My headers look awful, I've been thinking about getting cast HP manifolds and wonder about the difference in Horse Power. Also would anyone know the weight differences?
Cheers Everyone
 
I been researching the same thing and it’s a pretty big restriction with manifolds. Nick’s garage on YouTube does a Dyno comparison on a 440 that will tell you a lot. I think it depends on the build mild vs. wild my builder told me around 20% is the HP loss with manifolds. Guess it all depends on what you doing with the car

 
I have really been undecided on running headers or not on my 493 just don’t care for the ground clearance issues and the price tag.
 
I been researching the same thing and it’s a pretty big restriction with manifolds. Nick’s garage on YouTube does a Dyno comparison on a 440 that will tell you a lot. I think it depends on the build mild vs. wild my builder told me around 20% is the HP loss with manifolds. Guess it all depends on what you doing with the car


The horsepower loss has alot to do with how the engine is built, if its mainly a high rpm race engine with a camshaft with a narrow lobe seperation and very little difference on the amount of duration on the exhaust lobe compared to the intake lobe you will probably notice a good amount of power loss but if the engine is built with a fairly wide lobe seperation and the exhaust has a good amount more of duration on the exhaust compared to the intake with HP manifolds the power loss won't be as noticable escpecially if its mainly street driven.
 
I have really been undecided on running headers or not on my 493 just don’t care for the ground clearance issues and the price tag.
Not to mention, having to fuss with headers fairly often (according to brand, of course).
I've just had to get under the car and reposition the exhaust, then crank down on the collector bolts
AGAIN....shiyat gets old, man.
I'm sure having Hedmans has something to do with it, as does having these ridiculous 3" pipes, but....
dangit, I've had to tighten most every bolt on both sides, at engine and at collector, more than once
since the last engine install.
 
Merry Christmas Everyone, My headers look awful, I've been thinking about getting cast HP manifolds and wonder about the difference in Horse Power. Also would anyone know the weight differences?
Cheers Everyone

I run HP's on my old stock 440 and plan on running HP's on my 505 stroker being built. I went to Mr Porter of Porter Racing Heads and told him what I want and to use HP's. He massaged the Stealth heads and set them up for me to use a roller cam he had ground to his specs for the HP's. For me going to a 505 of any kind is going to be a huge improvement over what I have now and am sure I will be happy. It was also designed from the get go with HP manifolds in mind. But if you have always run headers and then went to HP's all bets are off I would think. Might be ok depending on what you expect. For me I don't know what I am missing with headers but the gains will be huge compared to what I have now. Don't blame you with the headaches that some say are very possible and the cost with headers. For me I just wanted a car that I can go anywhere anytime.
 
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Weight and heat enough reason to go with headers for me.
 
My car will be 100% street driven and don’t mind to lose a few horses it’s the torque you feel in the seat of the pants anyhow.
 
I think the use of manifolds is likely to cost 20-30 HP.
The loss would be more as you revved the engine higher.
 
Mopar built their engines for great response. The addition of headers in many applications actually caused more problems then they are worth. The may over heat the starter. The burn thru spark plug cables. So if you are not building a HP motor you may find it is better to stick to Exhaust manifolds. I am not the professional but I have had troubles before and have gone back to Stock Exhaust manifolds.
 
Weight and heat enough reason to go with headers for me.
I am curious, headers create more heat then factory exhausts. The may burn thru cables if spark plug cables contact them. They cause so much heat that they may cause the starter to over heat if you do not have a cover. They leak easy. They do not give you that much more power then one might think. The cause a lot of problems when working on steering. Just what I have experienced using headers.
 
I think the use of manifolds is likely to cost 20-30 HP.
The loss would be more as you revved the engine higher.

According to Nick's video above HP's lost 22.8 HP and 20.6 torque over 2 inch headers but all runs ended before 6000 rpms. I would guess the headers would shine above that and the HP's would shut down. Since my stroker will never see 6000 rpms I think I will be fine.Torque peak for both headers and manifolds peaked at the same rpms. Horsepower however peaked at 5700 and 4900 rpms with the HP exhaust manifolds..
 
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According to Nick's video above HP's lost 22.8 HP and 20.6 torque over 2 inch headers but all runs ended before 6000 rpms. I would guess the headers would shine above that and the HP's would shut down. Since my stroker will never see 6000 rpms I think I will be fine.Torque peak for both headers and manifolds peaked at the same rpms. HP however peaked at 5700 and 4900 rpms with the HP exhaust manifolds..

That’s me my stroker will never see 6000 rpm I’m thinking I’ll run manifolds and the option is there to run headers if the need ever arises.
 
I am curious, headers create more heat then factory exhausts. The may burn thru cables if spark plug cables contact them. They cause so much heat that they may cause the starter to over heat if you do not have a cover. They leak easy. They do not give you that much more power then one might think. The cause a lot of problems when working on steering. Just what I have experienced using headers.
Mine has the ceramic coated million dollar TTI’s. Under hood temperatures 100 degrees cooler with them. Weight savings huge.
 
Mine has the ceramic coated million dollar TTI’s. Under hood temperatures 100 degrees cooler with them. Weight savings huge.

How much ground clearance with the TTI and what diameter tubes?
 
Got headers out of my system when I was 18... almost 40 years later now and this is how it's gonna be until I'm gone, well unless I build a '68 Dart.. LOL

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With a larger capacity stroker engine the manifolds could cost you 50 hp.
You can get air fuel in but if you cannot get it out the cost will be more as engine size and revs go up.
 
With a larger capacity stroker engine the manifolds could cost you 50 hp.
You can get air fuel in but if you cannot get it out the cost will be more as engine size and revs go up.
Yes I understand that. I believe Mr Porter took that into consideration when he ground the cam for me to make the best of that situation. My car a 69 Fury III 2 door and weights in at 4100 pounds and has a 3.23 rear which I want to keep to blast down highways. What I am looking for is 500 to 600 ft lbs of torque down around 2800 to 5000 rpms to get this beast moving with ease. That is it's sweet spot. Not a drag car. Not a street racer but a real sweet cruiser with some hair on em.
 
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