Exhaust headers

[kenparker]

I have a new high performance engine in my almost finished S/W. Bored .60 over, B cam, enlarged (.073) intake valves, porting in the intake valve area, inserts and some other goodies. Currently, I have a stock Zenith and intake and Stock exhaust manifold on it. My plans are to replace the Zenith with the Weber carb and Weber intake manifold and replace the Exhaust with Headers.

My question to you fellers - What are the advantages and disadvantages to the Tube Headers vs the Cast Iron Header that are available? Your input is appreciated. Ken

[Cajun]

Tube headers are available from "Red's Headers" in both single and dual exhaust. I put the duals on my speedster. They sound and look good.

A local engine builder said that he tests somewhat higher HP with the headers.

Your intake valves are probably 1.73

[1931 flamingo]

I think the tube headers may "wear out" quicker,burn thru if o/heated, welds crack, etc. JMO
Paul in CT

[Purdy Swoft]

Tube headers give off more heat and won't last as long as the cast iron header.

[Jason in TX]

I put the Reds Headers dual header on my coupe. I was NOT happy with the quality when I received it but it was cheap. I had a friend do some TIG work on it and the muffler shop had to bend it to make it fit. But now that I've painted it, and done a lot of work to it, I'm happy. I went with no mufflers and the "sound" is excellent, but it is WAY too loud. Get glasspacks or cherry bombs.

[31Tudor]

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I am using the tube headers on a speedster. I had them aluminum powder coated. They have been on the car 12 years and still look like new.

[Larry Brumfield]

Because of the thin tubing, tube headers emit more noise than cast iron headers. I like the performance of tube headers but I never liked that tinny sound they produce in and around the engine.

Also, tube headers have more surface area so they give off more heat in the engine compartment. What will Mr. Ethanol think about that?

They also seem to rust easy and rot through unlike a cast iron manifold which will most likely last until you rot through 6 feet under.

BUT, a properly tuned tube header will produce more power because they optimize or tune the engine to run better in certain RPM ranges by creating a low pressure area at the exhaust port and the exhaust just naturally wants to flow out more easily when the valves open.


Larry B.

[MrTube]

I was under the assumption any quality exhaust components were always made out of stainless these days, including headers?

Or is it just that there is no stainless header for the model A?

Though honestly I have to wonder how much a free flowing exhaust really helps a flathead engine breath in the end.

[Pete]

Headers have a tinny sound as compared to cast iron manifolds.
They will last as long as long as needed if you take care of them.
The production ones available offer slight hp increase but are usually
poor quality workmanship.
No "W" type production headers are available. This type will show the most hp increase but are do it yourself. If building these they should have reversion dams and 34 inch downtubes for a model A/B..They should collect in a 4 inch tube..This info was collected from dyno tests.

[Larry Brumfield]

Originally Posted by MrTube

Though honestly I have to wonder how much a free flowing exhaust really helps a flathead engine breath in the end.

Why do you wonder this? When there's not much horsepower to start with every little improvement helps.

[youngrodder1929]

i have a reds header and a smittys glass pack on my a it seems to sound pretty good and really for less than 200 bucks you cant bitch quality to much lol

[Old182]

Steel headers are an excellent way of making more power than with a stock iron exhaust manifold IF the intake system is compatible. Engines are all air-limited (you can put fuel in with a coffee can, but you're stuck with the day's barometer regarding air). Steel headers are smoother and lighter than iron, and should be designed with equal length tubes (check Pete's note and the neat pic), and should match the exhaust port for smoothest flow. Typically, the tube diameter is the same as the exhaust valve, and tube length is based on what rpm range the engine is to be tuned for. The calculations I've seen refer to ending the tube at nodes or antinodes of the sound waves produced by the engine at the desired speed. If done correctly, the reflected wave will generate a scavenging effect (low pressure) that "pulls" exhaust gases from the engine, creating better breathing. More air in + more air out = more power = . The downsides of steel headers have already been posted.

[Pete]

"Typically, the tube diameter is the same as the exhaust valve"

Correct, and this will typically have the tube 1/4 inch bigger than the port exit in the block. This step is the reversion dam and little or no scavenging will take place without it. The pressure wave travels along the surface of the tube and has to have a wall to stop it and reflect it.

[Old182]

So THAT's what a reversion dam is...the info I read said the reflected wave would go all the way back the exhaust valve seat where it would then see a pressure difference in the cylinder and that reflected wave would create the scavenging effect. I don't dispute what you say, but I've seen a lot of small block Chevy gurus spend a lot of time matching the exhaust port to the header with no step. Is it simply another way of getting the same results or are V8s tuned differently or...? Your thoughts?

[PC/SR]

Pete: I have heard that the headers should be larger than the port but did not really know why, now I get it. Thanks. Would it make sense to use B headers on the A as a compromise given the difference in port sizes? The local exhaust guy wants a bundle to make the W/custom headers. I am running dual Holley 92's, HC head, Elgin cam. What do you think of Charlie Yapp's cast iron dual "y" types? Your intake looks like custom dual intakes with an equalizing tube and Stombergs adapted? Very nice, clean set up. How does the thottle linkage work? Picking your brain here, and hope you dont mind. Looking for ideas. I'm not building a track racer, but do want something more than usual. Thanks, Pat

[Pete]

Old182, on a 900 hp sprint car engine you probably could not tell the difference with or without reversion dams. It does help slightly on A/B's and flat V8's.

PC/SR, I am not familiar with Yapp's stuff....I think he is a dipshit.

On the engine in the pic, it had 4 intake ports with straight runners.
No equalizer...Standard 2 carb throttle linkage..Stromberg 48 carbs with bored oversize venturi's..Radius lifter cam with .488 lift.
10 to 1 compression ratio. Made over 160 hp on av gas.

[PC/SR]

Neat. How did you get 10:1? Lots of lift, lots of duration I assume. Running RPM? Really curious if you used babbitt or inserts. I assume full pressure. Thanks

[skip]

Since the exhaust runs through the block and not the head it does not matter if it's a tubular header [frit coated and heat wrapped] or a cast iron header until you decide to hog out the exhaust area in the block. At that point it would be important to 'blueprint' the racing block in these ares. Frank Odde's book on the Flathead V-8 details the whole complete argument of making flathead, 'A's or V-8's breath.

skip.

[Larry Brumfield]

Originally Posted by Old182

Steel headers are an excellent way of making more power than with a stock iron exhaust manifold IF the intake system is compatible. Engines are all air-limited (you can put fuel in with a coffee can, but you're stuck with the day's barometer regarding air).

I'm not speaking directly about Model A's but much of that depends on just how restrictive the stock exhaust manifold is regardless of the intake system.

[just plain bill]

Originally Posted by skip

Since the exhaust runs through the block and not the head it does not matter if it's a tubular header [frit coated and heat wrapped] or a cast iron header until you decide to hog out the exhaust area in the block. At that point it would be important to 'blueprint' the racing block in these ares. Frank Odde's book on the Flathead V-8 details the whole complete argument of making flathead, 'A's or V-8's breath.

skip.

I have an "A" engine that I have modified and I have tube headers on it. The off the shelf headers have been extensively modified to fit into the tight area left after fitting the engine into the after market frame purchased at a yard sale . I am from the school that developed before the use of flow benches and I perfectly matched the ports to the header plate as I was taught that any restriction reverse or other wise was 'bad" as it caused eddy points and would slow the flow. No modifications to engine exhaust ports other than opening the valve seat area to 1.540 and installing a 1.650 valve. I realize that this ole time info was incorrect but this incorrectly modified engine moved my 1500 lb. car to 82 MPH with a 15.9 ET. Also, this was with a "shade tree" modified "B" distributor and the coil off of my tractor