Do headers really help flatheads make horsepower

manifolds verses headers do headers make a difference?

 

It cant hurt. I would think any motor that breaths better will make more H.P.

 

My opinion. They help a bit on stock engines. They are crucial to realizing the potential of hopped up flatheads. And, they sound good.

 

Flatheads have some of the most restrictive stock manifold designs in history, some worse than others depending on application, so YES headers will help!

 

Some of the guys on the ford barn have done dyno testing on this very subject,from what I read on a stocker they don't give you anything as far as hp gains.I find it hard to beleive but thats what I read.I was told by someone else that they may run a bit cooler,with the headers.I would think they have to help,they certainly can't hurt plus running the duels will sound good.

 

You should pick up a copy of FLATHEAD FACTS by John Lawson, a great book that answers all these types of questions by actual dyno pulls. In his book he states and I quote "On a stock flathead engine there was no improvement when changing from exhaust manifolds to headers".
Get his book, it is worth every penny.

 

True. And upstream from the manifolds are some of the most restrictive exhaust ports. Headers can't hurt, but they won't help much until the ports are improved.

Bob

 

I put a set of cheap headers, glass packs and dual exhausts on my otherwise stock 50 Ford
flathead and while it may not make more horsepower it runs smoother down the road and sounds great and makes me smile. I'd do it again.

 

Here's a slice of an old chassis dyno/drag flog of an essentiall stock 239:

A repost:
Here’s a dyno/drag test from about 1954, excerpted from the 1955 HRM annual. Real numbers from these times are scarce, and even E.T.’s were rarely reported. Most drag results were strictly MPH.
Note a few things about these tests: They are modifications on an existing used car, not a full build up. They are entirely bolt-on mods on a stock 239 short block, without even a cam change. The HP numbers are rear-wheel chassis dyno numbers, NOT flywheel HP. Onward:

The car involved was a stock 1940 Merc club coupe, which would have been a typical back-row-of-the-used-car-lot teenager’s car in 1954. The engine was a commercial rebuild, described as “in neither excellent nor in poor shape” with 12,000 miles since rebuild. The pictures show it to have a Stromberg and a dime store chrome aircleaner, probably giving a slight power loss from stock.

Stock with distributor freshly strobed and new plugs (H 10), it pulled 69 HP at 50 MPH on the rollers and turned a blazing 17.23 @65.47 MPH at the Santa Ana dragstrip.

Test 2 added a Sharp super dual with two 97's, stock except for .048 jets (I would think a bit rich?). This produced a 16.56 @ 71.01 MPH, power peak moved to 80 at 55MPH. (Power was tested at speeds from 30 to 60 in high, with practically all mods showing improvement at all tested power levels, by the way).

Test 3 was with the addition of 8.5 to 1 rated finned heads; They carefully avoid stating or showing brands, I would guess because they had so many advertisers to offend. They were R type heads requiring changing out the shorter studs. This produced 84 HP at the wheels at 55, and went16.07 @74.99 at Santa Ana.
Test 4 added dual exhausts and a pair of Hollywood Deeptone mufflers, used with stock manifolds. 86HP, 16 flat @ 75.01.

Test 6 added a Harmon-Collins dual coil, which produced only trivial gains over the fresh stock distributor.

And that was it for that issue–only modifications that an ignorant teenager with $5.00 worth of tools could have performed in dad’s driveway on Saturday. I really wish they had gone on to a cam and headers, but no such luck. Bruce.


So there's a test showing slight gains with duals. Remember that early flatheads had very small single pipe...not surwe when they went larger, certainly by '42, don't know about this Merc.
Headers not tested there... might be more important on '49-53, with truly awful looking stock setup.

 

x big times 2

 

Different sizes, lengths, bends, changes in diameter, etc. will promote or hinder torque and horsepower. So short answer is yes, headers will make a difference. What difference, depends. There's lots of information out there on exhaust design. Whether you are talking about Briggs and Strattons or Fords, the basics will help you with your decision.

 

On the 49 up Merc engines the logs on the exhaust manifold is larger than the fords.

 

I ran 3 different flatheads all 8ba's , on Calverts Dyno last summer. We ran 3x2s ,4x2's ,Hillborns , MSD , Vertex, and two different sets of headers. We ran the 97s and Demons . Two motors were 292 c.i. And one was a 317 c.i. Isky roller in the 317. Best combo was vertex , 292 c.i. , Hillborn with taller stacks, bigger tube headers ,flat tappet cam.

 

What cams where in th engines.....?

 

YES,

The first thing I learned, 'bout building any Engine (Mill) IS.......

You can't do just One Thing an see (Feel) results.
It' a combination of many things,
Headers Carbs Ignition Balancing, On Flatheads......Porting & Relieving,
Cuttin' everother impeller off the waterpumps, light flywheel, etc.
And you must have Porter Muffs, Haveto ! and lots of $$$
Bye

 

Very interesting and very fast for a 3000? pound car with 86 rear wheel HP.Notice the MPH is very low for the ET .................
Shifting through old car road tests,that damn back lot more or less stock Flathead would beat a variety of far more powerful cars in the 1/4 mile.Cars with a slower ET,book road tests,57 283 Fuelie Chevy sedan,58 Ford 352 Interceptor,a huge variety of Olds,Pontiac,Mopars and the old flattie just loses to a 66 Mustang 289 271 HP by 3 tenths.
To good to be true?

 

What looks like it would work better? and in my opinion cast iron soaks some sound, tubes are louder, and must help somehow to use 2" main pipe. And if they are "out there" the cast iron looks lame, at least the original early manifold, late ones not quite so bad.
And making up the pipes was one of the most enjoyable part of the project.

 

Anytime you can make an engine breath better you will gain something, more in some engines less in others. Cast iron "Logs" with a crossover gets the gasses out but it's not the best set up.

This isn't Flathead relaited but it does show something. These are the results of dyno test using different type exhaust systems on a Y-block done by Ted Eaton on his 312 "Dyno mule" the only thing that was changed for each test was the exhaust. Notice the change in #s over the stock cross pipe exhaust with any other manifold/header.

http://www.y-blocksforever.com/forums/Topic55379-3-1.aspx?Highlight=header+test

 

I think the joker in the flathead ET deck when run through common HP vs 1/4 mile results is probably in the breadth of the flathead torque curve...the flathead can pull hard from 500 rpm so all the time spent pulling is pretty productive...
Also, remember that HP is a mathematical construct based on RPM vs torque; a mild flathead (and most '50's cars in general, OHV or not) does all its work below 5200 revs, meaning that the formula automatically produces low numbers.
look at the last national drags the flathead top eliminator (Cal Rice car, I think it was 1956).
The car defeated a field of blown chrysler hemis which had to be producing twice the power. To top that, Rice built the car with hemi and flathead mounting provisions, and ran the car at different events with each. The hemi produced slightly higher MPH than the flathead, the flathead was slightly better on ET...and so was chosen for the trip to the nationals.
Any research on THAT while thinking about horsepower only will hurt your head!
He did use headers, though

 

When I first got my 50 I had all kinds of things in mind that I wanted to do to the poor little flatty. But after I got it tuned up and reliable I found out I really liked it the way it was and I haven't had the heart to crack it open. With the exception of headers and dual exhaust it's stock. It's so quiet and smooth it's almost erie. It keeps up with traffic around town with no problem. It may only have 100 horsepower, but they're big horses. All that said, I really think the headers helped it breath better even with no other mods. That's just a seat of the pants opinion though.

 

headers are a start to building a performance mill. but a lot of oldtimers claim they are great for getting heat away from the engine. and they sound good.

 

V8 or banger ?

 

With exhaust ports on a ford v8 headers might be like a 3 inch outlet on a ricer muffler.

 

If I KNEW for a certain, absolute, positive fact that headers, glass packs and duals would not add one half of one horse power I would still run them. Other wise it just ain't a hot rod.

 

I think they help. I also think it depends on the type/shape. I think the center dump/Belond type is the best, but I also think that center exhaust port dividers work too. Installed correctly, of course

 

Recently dynoed a 295" Flathead and there was a nice 15+ increase in horsepower when switching from some home made headers with long pipes to a set of nicely fabbed shorter tubed headers with the larger center tubes and good looking collectors. Ted Eaton.

 

I'm in the same boat with Unclechet, I was going to go bigger cam, heads, dual intake...but once I got the headers on (1 3/4" all the way back both sides) and heard the cackle from the back end of the motor, oh baby. I have $60,000 lead sleds asking what I'm running to get that sound! While I would love to have a 292, I'll settle for a set of finned aluminum heads and a new 2GC carb this winter.

 

I don't have any hard fact or any dyno chart to show the enhancement in horse power that installing the headers on my flatty but it felt like the car ran better.

The original exhaust are somewhat restrictive. HRP

 

The logic function in our mechanical brains wants to say they help. Setting that aside, where does the power ultimately come from? The ENERGY that's in the FUEL, once burned at exactly the right time. Logic wants to say the engine will breathe better and produce more power, but where's the power coming from? How much better does it really have to breathe? What's the volumetric efficiency of the average flatty? Clearly nowhere near an OHV engine, right?

The sound/feel/breathe better idea is a maybe in my mind. If you're not going to PROCESS MORE ENERGY in the combustion chamber you're doing nothing. Once the OHV structure became common as well as the added efficiency, the OEMs were leaving some power behind in the name of comfort and profit. That power was easily exploited with simple bolt-on parts and tuning parameters. I probably agree that you do it for the sound and comfort more than power, and also to make things easier logistically for hot rod practices. I would toss a set of headers together as a matter of course and would probably care less if it made 4.791 additional HP, or in fact if it lost it.

But, BUT, BUT , do headers make a SBC run better? Sorry kids, I had to...

 

This goes back the the early 1970's when I was in High School. Our shop teacher was an old Hot Rodder, even owned a famous magazine roadster for a while. We had an engine Dyno, an old Stuska water brake that was donated to the school.
As an after school project we did some exhaust testing on two flat head motors. The first a stock, but relatively fresh 1936 221" motor. We ran it first with stock everything, including the exhaust system off the 36 Coupe. We then made our own dual exhaust using an old pair of Smithy's. We picked up 3-4 HP with no other changes. We then ran a set of Fenton Headers and found another 3 HP. Next we ran a set of tubular headers from a land speed roadster that were of unknown origin. It lost a little at 4800 RPM but had gained in the mid range. The conclusion was that it was over-scavenging at upper RPM and needed jetting which we didn't have the ability to do.
The second motor was a 286" with Evans heads, 9.5:1 heads, dual carbs and did the same testing. Over manifolds the Fentons were about 7-8 HP, But the mystery long tubes made over 20HP more. I can't remember the exact numbers (it was 40 years ago) but the motor was a little over 240HP