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Why Headers?
https://slantsix.org/forum/viewtopic.php?t=23413		 Page 1 of 1
Author:  bwhitejr [ Thu May 31, 2007 9:44 am ]
Post subject:  Why Headers?
Why would headers be better? The stock exhaust manifold is larger than any tubes of headers I have seen for a SL6. And besides, only one cylinder uses the manifold at a time. What am I missing here? Just ignorant, I guess. :roll:

Some one set me straight.

bwhitejr
Author:  SlantSixDan [ Thu May 31, 2007 9:52 am ]
Post subject: 
The idea behind headers is that they provide a lower-restriction path for the exhaust gas, since the bends are less severe. And, each pipe is much longer before they join together at the collector, so there's less pipe space that must be shared by the exhaust from multiple cylinders. If the headers are of the "tuned" variety, the pipe length works with the pressure pulses to extract the burnt gas from the cylinders.

That's the idea behind headers. Sometimes they work that way, sometimes they don't. And there are negatives to be factored in as well (noise, leaks, increased heat in the engine compartment). Furthermore, compared to e.g. Dutra Duals (split cast iron exhaust manifold system), a set of headers really only offers a practical reduction in exhaust restriction at extremely high engine RPMs many/most of us never see.
Author:  dakight [ Thu May 31, 2007 1:25 pm ]
Post subject: 
One other factor is that headers can be tuned by carefully choosing the length and diameter of the tubes to give more efficient scavenging of spent gasses. An open manifold does nothing to prevent pulses from nearby cylinders from interfering with each other. Headers will have a power band in which they operate best. Long headers work better for low RPM applications while shorter headers are more optimum for high RPM use.
Author:  Wesola78 [ Thu May 31, 2007 2:59 pm ]
Post subject: 
The two previous posts summed it up. The only thing I might add is that dutra duals are more practical for a daily driver than headers, but that is just my opinion. Some folks have headers on their daily driver slant sixes and really like them. So, whatever floats yer boat man!
Author:  70valiant [ Fri Jun 01, 2007 1:58 pm ]
Post subject: 
Dutra duals are also much more expensive than headers.
Author:  slantzilla [ Fri Jun 01, 2007 2:07 pm ]
Post subject: 
Whenever I get my Cliffords back from Harold I will do a back-to-back test either on a chassis dyno or at the track and we will see the exact difference between DD's and headers. The motor in my car is pretty stock so I think it will be a fair test. :D
Author:  slantvaliant [ Fri Jun 01, 2007 2:53 pm ]
Post subject: 
Quote:
Dutra duals are also much more expensive than headers.
True for initial purchase, assuming appropriate headers are even made for your car, and the vendor actually delivers.
Dutra's should last a lot longer than headers. Once you start replacing headers, they aren't such a bargain.
Author:  Ron Parker [ Fri Jun 01, 2007 4:26 pm ]
Post subject: 
Dutra Duals are the way to go for a street car or street/strip car. I have never had any luck with headers on a built engine street car. Once a complete exhust system is on the cars that I have tried the tube headers flex and move. On a Slant that could cause problems because you can not torque the head/intake bolts real tight. But i have had problems with small block cars too. If it is a all race car I would use tuned headers. Anything less I would use Dutra Duals. Thanks Ron Parker :D






Jaggers Fabrication Slanted Attitude Dart
Author:  slantzilla [ Fri Jun 01, 2007 6:31 pm ]
Post subject: 
As much as I dislike Clifford, I have to say that my headers are in very good shape for being 10 years old. They also spent at least 4 winters on the street. They are not coated, and the original paint took all of maybe 10 minutes to burn off. :shock:
Author:  Mister Twister [ Tue Jun 05, 2007 9:14 am ]
Post subject: 
Hummmmmmmmm,looks,performance,looks,performance,looks,performance!!! Sounds like Header/Headers will work for us. :twisted:
Author:  AnotherSix [ Wed Jun 06, 2007 11:34 am ]
Post subject: 
Whether or not headers make more power depends on the quality of the header too. Even on v-8 cars they often do not do as much as one would hope on a street car. Often the engine makes less low end torque, marginally more top end power.

I have used quite a few different headers on street cars. I have somewhat resolved that they do not do much on a setup that is running less than about 220 degrees of cam duration at .050". Below that you just don't have the rpm range to need them. Cleaned up stock manifolds might do better. Turbo engines are a different story, but then they are pretty much custom and usually stainless. Turbo engines also can have 40 plus psi pressure in the exhaust under boost, much higher than you would ever see in a normally aspirated engine.

The only trouble free headers I have used are Doug Thorley try -ys. I used them on a 440 motor home and I have them on my 69 Chevy wagon. They actually fit, are nice and thick, quiet and chrome plated. Power overall is good with no bottom end loss. Of course they don't make them for a slant.

I just picked up a new pair of Cliffords for our slant, but not from Clifford. One of those sets on ebay. I paid less and actually have them already. I may or may not run them. It is not a daily driver. I suspect they will not be available down the road and I may stash them for later use.

The 1/2" flanges are really only 7/16", there is one tube to flange weld that is incomplete by 1/8", easy enough to fix. They may or may not fit without work. The flanges do not look flat by eye. They will need a going over before actually being usable in my opinion.

I scaled them at 13 lbs 4 0z. without collectors. A stock sixties exhaust manifold I have that is reasonably clean scaled at 24 lbs 14 oz. So the weight savings will be less than 11 pounds with collectors.

If you have a race car you probably want them. For a daily driver, kind of an ongoing problem to deal with.
Author:  Mister Twister [ Thu Jun 07, 2007 8:56 am ]
Post subject:  Header/Headers
Sounds like a discription of a dirt bike almost, power band, when we mounted 3 diff sets of Headers all diff range of the same sound, some where around 3000rpm. I know someone has heard the same thing, I am not crazy. I don't hear this when installed on the V8. Is this the slant's sound, or the inline 6?
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