Headers vs. Exhaust Manifolds ~ 'Let The Debate Begin'

[69 Cuda 440]

'Headers' vs. 'Exhaust Manifolds'

Just what does a set of 'typical run' Headers deliver in Horsepower gain
over a set of 'factory stock' Exhaust Manifolds in a 'Stock Engine'.

For one, there is a difference between 'Big Block' and 'Small Block' in
Horsepower gain.

~ Small Block ~

Generally, most of the 'exhaust system experts' state that a set of
Long-Tube Headers with {1 5/8" Primary Tubes} will produce a
'minimum' of 15 Horsepower over the 'factory stock' Exhaust Manifolds,
and running thru the exhaust system piping {primary pipes, mufflers
and tail-pipes}.

In other words, a set of 'Street-Type Headers' running closed and connected
to a conventional Exhaust System should gain you +15 Horsepower.

 

[abodyjoe]

Just what does a set of 'typical run' Headers deliver in Horsepower gain
over a set of 'factory stock' Exhaust Manifolds.

kinda a loaded question..

it all depends on the build itself. too many variables for an absolute answer.

 

[LocuMob]

The headers I put on my Polara breathe way better than my leaky exhaust manifolds on the 440. I've heard all things being equal with the build, I should have gotten 20hp.

 

[famous bob]

The headers I put on my Polara breathe way better than my leaky exhaust manifolds on the 440. I've heard all things being equal with the build, I should have gotten 20hp.

what`s to debate? headers flow many times better than any cast iron manifolds .

 

[69 Cuda 440]

kinda a loaded question..

it all depends on the build itself. too many variables for an absolute answer.

A-Body-Joe


'Brand-X' Headers installed on a factory stock {1970 'Duster 340'} in place of the
Exhaust Manifolds.

I'm sure you can come up with an approximate Horsepower Gain.

And you should 'rinse off' your Avatar Girl.

 

[abodyjoe]

I'm sure you can come up with an approximate Horsepower Gain.

only a dyno or time slips will give ya the real answer. after proper tuning ofcourse..

 

[TF360]

The only negative thing with Headers, especially on a a-body, is fit. Most do not fit just right.

 

[abodyjoe]

The only negative thing with Headers, especially on a a-body, is fit. Most do not fit just right.

tti fit awesome on my dart. no denting , plenty of ground clearance and tons of plug access..

 

[mderoy340]

If you are doing a resto or hate headers stick with manifolds.

Here's 2 dyno tests with #s. 1st test with dyno mufflers, 2nd test open pipes.
It's not just about HP #s; bottom end torque is up and that is exactly what you need on a street/strip car.

http://www.moparmusclemagazine.com/...ing_headers_and_manifolds/hooker_headers.html

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0307_mopar_crate_engine_exhaust/

 

[JBrian]

What I get out of this is if I have to smack my brand new TTI headers for my 6.1 Hemi, it's not going to make any difference in power generated, it will just look ugly!

 

[rumblefish360]

I liked those old articles but wished they stepped up the power program on the engine.
I'm running the Hooker Super Comps on my mostly stock 5.9. While I will get to a cam later, I'm still OK with the choice due to fit and a much cheaper price than the tti header. The cost difference between the two is a few bucks but huge when there's no coating.

Sometimes, it is a budget thing.

 

[replicaracer43]

A lot of these header vs manifold discussions are based on some dyno test of a typically low output engine, to make the argument that the manifolds are as good as headers. Like most things engine related, its all build specific, but a stock 2 barrel 318 wouldn't see as much gain as better built 360 for example in most cases. But take a 500 HP 408 stroker and it would be a much bigger difference.

 

[69 Cuda 440]

Correct Replica Racer 43

Even on a 'basic' 318/200 HP, you will gain something with
a set of long-tube Headers.

On the 'Chassis Dyno' we usually saw an increase of
{10 to 12} Horsepower @ 3000 RPM's on the Mopar 318
with it's 'fire-breathing' BBD 2-Barrel.

And with a nice improvement in Low-End Torque as well.

With the small primary tubes, we could gain approximately
25 Ft/Lbs. of Torque @ 3000 RPM's.

 

[Locomotion]

As with an intake or cam change, it may be helpful to recalibrate/optimize the carb (jets/squirter/accelerator pump) to get the most out of a change in the exhaust system.

 

[Captainkirk]

what`s to debate? headers flow many times better than any cast iron manifolds .

^^^^^^^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^

I always look forward to your posts, 69Cuda, but I don't see a debate here. Headers gain +15HP on a SB LA motor? No-brainer so far....

 

[mderoy340]

As with an intake or cam change, it may be helpful to recalibrate/optimize the carb (jets/squirter/accelerator pump) to get the most out of a change in the exhaust system.

I agree! The articles I posted were just bolt on and run. They show a positive trend for headers. If the engine was tuned after every change the trend would of been wider IMO.
I recently changed from 73 340 exhaust manifolds to Summit headers and their 2.5 inch exhaust and the performance is night and day.

 

[duster360]

I personally would like to see how this turns out.

 

[67redcudavert]

In late '73 I bought a new '74 B300 van with a 318, auto and 3:73 gears. It was not very peppy. In the summer of '74 I got a custom dual exhaust system with turbo mufflers installed on it which did nothing to change the performance of it, but it did sound a little better. In '75 I installed some Cyclone brand headers on it, wow, what a difference, it had a lot more grunt.

It turned out that the manifold outlet was maybe 1 1/2, 1 3/4 in. diameter so that's why the headers were such a major improvement. Of all the vehicles that I have put headers on over the years none of them showed such a dramatic change like the van did.

I also found out through personal experience that some brands of headers are much better than others. My van saw use year round so after 3-4 years the headers rusted out. The replacement headers were a different brand. After installation I could tell I lost power. In physically comparing the two it was obvious that the Cyclones had a lot more thought put into their design. It proved to be a classic example of you get what you pay for.

In another 3-4 years I needed to replace the headers again so this time a bought another set of Cyclones, after installing them I could tell that the lost power had returned.

 

[stroked340]

Not even worth discussing headers all the way..we use to remove the stock manifolds and throw them in the trash all the time

 

[crackedback]

A lot of these header vs manifold discussions are based on some dyno test of a typically low output engine, to make the argument that the manifolds are as good as headers. Like most things engine related, its all build specific, but a stock 2 barrel 318 wouldn't see as much gain as better built 360 for example in most cases. But take a 500 HP 408 stroker and it would be a much bigger difference.

Agreed.

 

[roccodart440]

only a dyno or time slips will give ya the real answer. after proper tuning ofcourse..

Read the comparison of Schumacher's (which blow away stock manifolds) vs. TTI's.

Almost a 1/2 second in the quarter difference in the same car with a mild build.

It take a hell of a lot more than 15 hp to make a change like that.

My car really woke up when I went to TTi's from the schumachers.


In regards to the whole low end BS. I call BS. More often than not you'll see an increase across the range. Been there done that with the whole intake comparisons.

 

[duster360]

I think some of you are not catching what the first sentence is saying. 'Stock Engine'

'Headers' vs. 'Exhaust Manifolds'

Just what does a set of 'typical run' Headers deliver in Horsepower gain
over a set of 'factory stock' Exhaust Manifolds in a 'Stock Engine'.

 

[duster360]

This one also.


[QUOTE=69 Cuda 440


'Brand-X' Headers installed on a factory stock {1970 'Duster 340'} in place of the
Exhaust Manifolds.

I'm sure you can come up with an approximate Horsepower Gain.

 

[Inertia]

I seem to remember the Magazines I read during the day,, said to expect 10 - 15%hp increase,, but I respect 69Cuda440 reference material.

This is the way I see it.. .

An exhaust manifold is about a 2 inch inside dia pipe, that has 4 entry doors in a row, leading to one exit door , of 2” dia.. at one end..

While running, the manifold is a high pressure area ,cuz when an ex valve opens, it is greeted by all the exhaust from other doors all trying to get out the small door at one end.. The exhaust trying to get to the exit, is blown backwards as another door between it and the exit opens,.. Also consider that the piston is forcing exhaust out as it comes up, but before the ex valve can close, another exhaust valve opens into manifold,, thus actually blowing exhaust (extinguisher) back into cylinder.. So the cylinder is still partially full of extinguisher, as the intake opens and takes a smaller charge of fuel, cuz cyl isn’t empty.. and mixture is contaminated, so less power… protract that,.. then consider..

While running, long tube header is low pressure, the exhaust valve opens and is greeted by an empty tube, that actually has vacuum created by the pulse of hot gas that’s halfway down a 3 ft. pipe,, aaaaAND that pulse of exhaust is being scavenged into the collector by the flow of gasses entering from the other pipes,,.. when the piston rises in the exhaust stroke, there is little resistance as the gases are sucked out, (more power) when the ex valve closes, the cylinder is nearly empty, with no loss of power forcing exhaust gasses into manifold,.. intake opens,, and full charge of uncontaminated fuel fills the cyl. (more power)

And I maintain long tube headers is the most cost effective way to gain horsepower..

jmo

 

[69 Cuda 440]

Brand 'X' Headers

* Appliance Headers
* Black-Jack Headers
* Cragar Headers

These 'Brand-X' Headers were 'The Bargain Headers'.

The tubing, bends and collectors were fine, but the 'welds' around the
port-openings of the 'Header-Flange' were usually atrocious.

And sometimes the 'Flange-Headers' were not square {'Exhaust Leak City'}.

Still, for a low-cost Header {sometimes $89.99} on a weak street machine, they gave you a decent sound and a guarantee of some additional Horsepower ^^^.

And, the 'Chicks' loved the decals. They always made your Car go faster.