Exhust Headers

[Mike snyder]

http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWA:IT&viewitem=&item=170168990971&rd=1

These are for sale on e-bay. Has anyone used them? And what did you think of them? What are the other options that are out there?
Thanks,
Mike Snyder

 

[Jeff Scoville]

These are made through a member here (see the add in the for sale section)

 

[atallamcs]

header

Hi Mike,

Many members have bought these--all telling me the header is great. Ian even bought one--you might want to ask him. I personally think there is no comparison to the ones sold by SS--the quality alone is superior, just my opinion.

Bill

 

[RootesRacer]

Hi Mike,

Many members have bought these--all telling me the header is great. Ian even bought one--you might want to ask him. I personally think there is no comparison to the ones sold by SS--the quality alone is superior, just my opinion.

Bill

But why not equal length?

 

[Bill Blue]

Jarrid, it seems to me the question could also be posed. "Why equal length?".

Equal length concentrates all the benefit of tuning into a narrow power band. Fine for racing or to prop up a weak rpm range. Unequal length spreads the benefit out over a wider band. Good for street use. The effect is not as strong, but the area under the curve is roughly the same. If a person is going to go to equal length headers, they should be designed with a specific result in mind so the benefit can used to max advantage. Headers tuned to the wrong rpm range will do you little good. For generic street use don't the unequal length do just as well?

Bill

 

[RootesRacer]

Jarrid, it seems to me the question could also be posed. "Why equal length?".

Equal length concentrates all the benefit of tuning into a narrow power band. Fine for racing or to prop up a weak rpm range. Unequal length spreads the benefit out over a wider band. Good for street use. The effect is not as strong, but the area under the curve is roughly the same. If a person is going to go to equal length headers, they should be designed with a specific result in mind so the benefit can used to max advantage. Headers tuned to the wrong rpm range will do you little good. For generic street use don't the unequal length do just as well?

Bill

Ok, fair argument, but there already was an aftermarket tri-y header sold (in stainless) sold by SS. Now there are mentions of quality issues, I have no comment to this effect since Ive never bought one.

Seems to me that folks that would pony up the coin for a header, would desire something not already available, or something that is somewhat superior to stock. After all, the stock SV cast exhaust is also a tri-y and flows surprisingly well compared to the earlier headers (which were abandoned in favor of cost). I ran a SV exhaust on the alpine with EFI for years, and when I swapped over to a factory header, the only change was the ticky sound you get from the thin tubing.

I waited for years looking for someone to supply a quality equal length header, but one day I saw a custom one on ebay and bought that sucker up.

Trust me here when I say, those in the know and racing rootes stuff would prefer and pay for a quality equal length header. Plenty of folks have already paid top dollar for one offs.

 

[V6 JOSE]

Bill,

I have seen intake systems that used different length runners, so that it would spread the power curve over a wider range, but I have never seen an exhaust system that had different length tubes for the exhaust. The idea is to get every cylinder to breathe the same, so that there is no restriction. Having different length exhaust pipes, just introduces another complication to tuning the engine.

In my personal experience, equal length tubular headers are the best way to go on a street or race engine. Most stock exhaust manifolds are of an unequal length design and are the biggest restriction to power. This is why every professional engine builder I have dealt with, has recommended equal length tubular headers, for any high performance application.

Jose

 

[Bill Blue]

Bill,

I have seen intake systems that used different length runners, so that it would spread the power curve over a wider range, but I have never seen an exhaust system that had different length tubes for the exhaust.

Jose

I have, years (maybe 30?) ago on Chebby headers. They were pretty common around this part of the world. You didn't even have to get the tape measure out to know they were not equal length. I was pretty surprised as I was used to looking at the Alpine headers.

I have no problem with equal length headers, especially on high performance engines. But we are talking about engines that are most likely medium high performance and will probably be used on the street. Lots of different cams, different carburation, compression ratios and displacements. Just don't see how one header configured with equal length primaries can be really effective to all users in that scenario.

Do power restrictive stock manifolds restrict power because they are unequal length or because they do not flow worth a crap?

Bill

 

[V6 JOSE]

I have, years (maybe 30?) ago on Chebby headers. They were pretty common around this part of the world. You didn't even have to get the tape measure out to know they were not equal length. I was pretty surprised as I was used to looking at the Alpine headers.

I have no problem with equal length headers, especially on high performance engines. But we are talking about engines that are most likely medium high performance and will probably be used on the street. Lots of different cams, different carburation, compression ratios and displacements. Just don't see how one header configured with equal length primaries can be really effective to all users in that scenario.

Do power restrictive stock manifolds restrict power because they are unequal length or because they do not flow worth a crap?

Bill

You've answered your own question. If all the tubes are equal. all the cylinders breathe the same. You can change the characteristics of the exhaust, by making them shorter or longer, to accommodate cam, carburetor and other variables but to be most efficient with any combination, they all need to be the same length.

Most stock manifolds are crappy, but even the manifolds that came from the factory on a high performance engine, were pretty nice, but by necesity, were of an unequal length design. The first thing that most guys change, when trying to get better performance out of their engines, is a good set of equal length headers. I believe that any engine, stock, slightly modified, or full on racer, can benifit from a good equal length design.

Of course, I can't convince you if you don't want to be convinced. If they weren't of benefit over the unequal length headers, why do so many race mechanics spend the extra money to buy/fabricate them?

Jose

 

[Bill Blue]

Jose, I really did not have a question. But I'll pose one: When an engine builder hands the engine over to the customer, does he say "Slap on a set of equal length headers. Don't get too hung up on primary pipe size on length."?

To me, that is what Jarrid is proposing when he asks Bill with "Why not equal length?"

Bill

 

[V6 JOSE]

Jose, I really did not have a question. But I'll pose one: When an engine builder hands the engine over to the customer, does he say "Slap on a set of equal length headers. Don't get too hung up on primary pipe size on length."?

To me, that is what Jarrid is proposing when he asks Bill with "Why not equal length?"

Bill

The builder probably doesn't tell his customer that, because he assumes that the customer knows enough to go with the equal length header. The size of the primary pipe and stepping the pipe is very important too, because you want the highest velocity maintained in the pipe, but that doesn't have anything to do with equal length for the pipes.

Jose

 

[Bill Blue]

The builder probably doesn't tell his customer that, because he assumes that the customer knows enough to go with the equal length header. The size of the primary pipe and stepping the pipe is very important too, because you want the highest velocity maintained in the pipe, but that doesn't have anything to do with equal length for the pipes.

Jose

So if Bill were to have some equal length headers bent up what size and length primaries should he specify?.

 

[V6 JOSE]

So if Bill were to have some equal length headers bent up what size and length primaries should he specify?.

Bill,

The equal length headers are important for normally aspirated angines. I guess I should have specified that. A turbo engine has back pressure in the exhaust system, so equal length isn't critical. If I were you, I would talk to a turbo specialist, to get his opinion on what you should use, but if you can't find one to talk to, I would get a book on turbo installations and systems.

The headers for my turbo Alpine weren't equal length, but that didn't really affect it much, because there was 25lbs. of back pressure, when yhe engine was experiencing 10lbs. of boost. What I would suggest is that there be no kinks or tight turns in the header, and put as big an exhaust pipe after the turbo. Having no back pressure on a turbo is very important. If you could get away with running an open pipe straight from the turbo, would be the ideal, unfortunately, most municipalities require some sort of muffler, even though turbo exhaust isn't that loud.

Jose

 

[Bill Blue]

Jose, some confusion here with names. When I mentioned Bill, I was referring to Bill Atalla, who makes up a half dozen headers at a time and sells them to various Alpiners. Not Bill Blue who is lucky to have a manifold to bolt the turbo onto.

Sorry 'bout that, Chief.

Bill

 

[mike_also]

The real tradeoff

Sorry, I know this string is old, but had to jump in and expose my ignorance. In a steady flow fluid system the shortest piping path between two points implies less wall friction implies less "backpressure." I don't know if the same applies equally or at all with a gas system but have often wondered if the tuning advantaged gained with equal length exhaust isn't lost with the tortuous bends necessary to achieve it.

 

[RootesRacer]

Sorry, I know this string is old, but had to jump in and expose my ignorance. In a steady flow fluid system the shortest piping path between two points implies less wall friction implies less "backpressure." I don't know if the same applies equally or at all with a gas system but have often wondered if the tuning advantaged gained with equal length exhaust isn't lost with the tortuous bends necessary to achieve it.

A engine exhaust system is not a steady state system.

Pulses of exhaust gas get sent down the tube, when the tube (header) is designed so that at a given rate of pulses (engine RPM), the resonance of the tube(s) scavenges the exhaust from the head, which actually allows extra draw on the intake. Such a system can and actually do in many cases improve the volumetric efficiency of the engine beyond 100%.

As for tortuous bends, yeah a poorly designed or built equal length header can inhibit flow, but if you look at most headers, the angles of the bends are slight, and the closer cyls to the collector tend to have longer straighter runs prior to bends to give them the extra length needed to match them to the farther cyl lengths.

 

[mike_also]

A engine exhaust system is not a steady state system.

A steady flow open system is not synonymous with steady state operation - that's an apples and oranges comparison. Sorry about mislabeling it "steady flow fluid system;" it's been thirty or more years since they firehosed me with this knowledge.

As for tortuous bends, yeah a poorly designed or built equal length header can inhibit flow, but if you look at most headers, the angles of the bends are slight, and the closer cyls to the collector tend to have longer straighter runs prior to bends to give them the extra length needed to match them to the farther cyl lengths.

Thanks. I'll review PAW and Summit catalog Mustang header pictures to check this out.