Which Headers

[jeepguy1948]

This question is probably not for the purist’s out there. I am in the process of choosing headers. As far as I know, there are 3 types. Tube (Like From Red’s), cast iron 4 into 1, and the Charlie Yapp/Secrets of speed 2 into 1 cast iron. There may be more that I have forgotten or don’t know about. Who likes what, and why? (Yes, I am using a downdraft intake)

[Richard in Anaheim CA]

1. The cast iron "header" is attractive and popular. It isn't the most efficient for making more power but better than the stock manifold

2. Charlie Yapp's cast headers are attractive but the wrong cylinders are connected together for optimum power. 1&4 should be together and 2&3

3. Reds Headers will produce the most power and their long length will maximize torque.

Richard
Anaheim CA

[nkaminar]

I did not see any difference in power up to 3,000 rpm between some tube headers and a stock exhaust manifold with a performance Ares muffler. I have a Weber carburetor and high compression head (6.5:1). I think if you are going racing then headers make sense, otherwise I would stick with the stock manifold. Or use the headers if you want the engine to look cool.

[updraught]

Can't see how a low compression engine can create the "suck" from headers when the exhaust leaves the head by tuning the exhaust pulses with equal length long tubes.

[nkaminar]

When I was in college, a lifetime ago, I studied scavenging and learned about wave propagation and how that could suck exhaust out. Now I have learned how the design of the exhaust valve and port at the head (or block) can be made to suck exhaust out. I still think that the wave propagation works and is important, but that the whole exhaust system is more complicated and all tied together.

For an exhaust system to be helpful it has to be designed for the engine and the rpm that the engine is used at. Even a low compression stock Model A could benefit from the right exhaust system, but the "header" pipes would have to be very long and probably be collected somewhere in the middle of the car. The collection is important because the pulses from the different cylinders reinforce each other.

When in high school I experimented with a Briggs and Stanton engine from a lawn mower by changing the length of the exhaust pipe. Those old engine had a pipe thread where the exhaust went into the block so it easy to change the length by using different length water pipes. This is an interesting experiment to do and easy with the right engine. A 10 foot pipe makes the engine run badly as the exhaust pulse returns to the exhaust valve at the completely wrong time.

The exhaust positive (pressure) pulse travels down the exhaust header at the speed of sound in that hot gas. It then reverses at the end and the negative pulse travels up the header, again at the speed of sound, to suck out the exhaust. So the length can be calculated based on this. But the final cut is made by testing. If there is a significant overlap of the intake and exhaust valves the suction at the exhaust valve can also help to suck in some fresh air and fuel.

[ModelA29]

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These little exhaust scavengers help performance greatly. I had one on a 2.8L Capri and it would keep up with a 1966 HiPo Mustang.

[johnneilson]

Good question
You will get opinions
Logic would suggest a tube header will just offer better performance than a cast manifold type
This is not always true
Besides a 10% performance difference is on the order of 5-10 hp

If you are going above 250 hp you need a tuned system
For that start with 1-3/4” for 10-11” then step up to 1-7/8 for 22-24”
Then into a merge and 2-1/2 exhaust

J

[Gene F]

About 1980 Cyclone came out with headers for V-8 engines with a little cup just beyond the engine head. It was called anti-reversion header. I was told that Cyclone had a patent for that little development, and the technology was proven on a dyno. The idea was to manage the backpressure.

At that time I worked for a professional dragracer (super stock) and Cyclone invited him to bring his car to them, and they hand made a set of large tube headers for his car. Of course he put their sticker on his car. As I recall his car did pick up a bit from this modification.

I'd think the downdraft carb would help more than the exhaust system.

[Pete]

In an exhaust system designed to scavenge, the pulses travel along the tube right against the pipe wall, not down the middle area. It is a pulse, not actual gas flow.

A 1/8 reversion step is definitely worth the effort on a flathead race engine with "W" headers.

There was a book written by a guy named Ricardo many years ago explained the whole thing so any rocket scientist could understand it.

[CarlG]

This is what I have, I'm satisfied with it.

[Dodge]

I'm using a Dan Price Header, DAN4BANGER and modifing the collector for low end torque.

[bruceincam]

I've just installed the Red's tube header. It was nicely built, finished pretty well and fit great. I primed and painted it with high heat stuff and then wrapped it. Just finished a couple of weeks ago and so far, I really like it. First impression was that I could feel more low end torque and power. It ran much "more freely". FWIW

[Jim Brierley]

4 into 1 tube header is the most efficient but at the RPM most guys run with their A's, it makes little difference. Cast iron headers or manifold retain heat and, I've found, make your car hotter inside.