[Joe428]

Hey guys I have a set of shorty headers on my 355 sbc and have heard that the long tubes provide a better exhaust flow, therefore a "little" better power gain, is this true?

[eric32]

I have two chevy s10's with v8's in them both and one has shorty headers and the other has long tube headers.

I am not an expert on headers but from what I have read long tube headers will make more power overall then shorty headers but shorty headers are way better then exhaust manifolds though. I don't have much experience except between my trucks but they both run very well and good with a dual exhaust system on them with turbo mufflers and have no back pressure issues.

In a nutshell the bigger the header and longer to some degree and if they are tuned well more power will be made to some degree with a trade off at a certain point with the tube size.
Eric

[Joe428]

Thanks Eric my dads c10 has long tubes and my c10 has shorties so I was wondering the plus and minuses Thanks for your reply I appreciate it.

[oldbogie]

Originally Posted by Joe428

Hey guys I have a set of shorty headers on my 355 sbc and have heard that the long tubes provide a better exhaust flow, therefore a "little" better power gain, is this true?

Actually they don't provide better flow, what long tubes do is cause a deep pressure depression that pulls really, really hard on the intake during overlap. This gets the speed of the incoming mixture up well before it would be if it just depended on piston movement. This enhances the ramming of mixture into the cylinder.

Shorties do a good job of emptying the cylinder of exhaust but don't offer much ram aid because they don't generate very strong negative pressure waves.

Getting more mixture into the engine with these reverse negative pressure waves is why long tube headers become increasingly effective as cam duration and overlap periods get longer. With a mild cam where there is more dependence on efficient expelling of the exhaust than pressure wave utilization, there isn't a lot of difference between short and long tubes. To repeat myself it takes a decent cam, high compression and to some extent high RPMs to really get what long tube headers can deliver. The back side is they can over-scavenge the cylinder which will require richening the mixture, but that's another subject.

Bogie

[Joe428]

Thanks bogie my motor is 10.9 - 1 compression and has a blower/nitrous cam...would I benefit from long tube headers?

[oldbogie]

Originally Posted by Joe428

Thanks bogie my motor is 10.9 - 1 compression and has a blower/nitrous cam...would I benefit from long tube headers?

It's all additive, the harder the exhaust pulls on the intake just puts that much more on top of what the blower and laughing gas deliver.

Bogie

[F-BIRD'88]

A supercharged motor is not so dependant on the scavenging effect of the long tube headers. The short tubes are ok as long as they are big enough
to get rid of all the exhaust.

[ap72]

Originally Posted by F-BIRD'88

A supercharged motor is not so dependant on the scavenging effect of the long tube headers. The short tubes are ok as long as they are big enough
to get rid of all the exhaust.

Supercharged engines don't bennefit from exhaust scavenging?

[SSedan64]

Ap72 is that the Liberal Spin of Fbird88's Post?

[Joe428]

So if in the near future I have plans of going blown and or nitrous should I pick up a set of the 1 3/4 long tubes?

[ap72]

Originally Posted by Joe428

So if in the near future I have plans of going blown and or nitrous should I pick up a set of the 1 3/4 long tubes?

. No headers are still important on supercharged engines. They still work as they are designed to. Tuned exhauast has a dramatic effect on na, supercharged and turbocharged engines.

[bentwings]

I've been running supercharged cars and turbo charged trucks since the 60's and I can assure you "tuned pipes" make no improvement and can hurt if the pipes are not big enough.

My current ride has short headers that I cut the 2 1/2 inch collector off and added a 3" carefully smoothing the tubes to blend. They were then coated with Jet Hot to keep underhood temp in line. I also run 3" ex all the way back to the rear of the car. It took only 3 u-bends to make the complete ex from the headers back. No X of H pipe either.

The T-bird SC is another example. Headers were not available for a long time but when the 3" ex came along the cars began to take flight. This is just a 3.8 liter motor too. One of the aall time best bolt on's I ever did.

The funnycars all have 2 1/2 tubes with an insulator jacket. These are angled out and back and up. There is a very large thrust component from the fuel cars somewhat less from the alcohol cars. If there was a tuning effect believe me the fuel guys woud be using it.

My Cummins diesel has a 4" pipe all the way back and no muffler. I get up to 28 pounds of boost.
Many guys have tried all sorts of different pipe sizes on these. Anything over 4 in is fine untill you get to the 600 hp/1200 ft lbs range at the rear wheels. Then a 5 in works to advantage. There have been many attempts to make fancy stainless steel "header" for these and none have worked. the stock manifold or the 3 piece replacement are plenty good for this work horse.

Tuned ex is fine for NA but leave it home if you run the blown stuff. The bigger the better.

[ap72]

Originally Posted by bentwings

I've been running supercharged cars and turbo charged trucks since the 60's and I can assure you "tuned pipes" make no improvement and can hurt if the pipes are not big enough.

My current ride has short headers that I cut the 2 1/2 inch collector off and added a 3" carefully smoothing the tubes to blend. They were then coated with Jet Hot to keep underhood temp in line. I also run 3" ex all the way back to the rear of the car. It took only 3 u-bends to make the complete ex from the headers back. No X of H pipe either.

The T-bird SC is another example. Headers were not available for a long time but when the 3" ex came along the cars began to take flight. This is just a 3.8 liter motor too. One of the aall time best bolt on's I ever did.

The funnycars all have 2 1/2 tubes with an insulator jacket. These are angled out and back and up. There is a very large thrust component from the fuel cars somewhat less from the alcohol cars. If there was a tuning effect believe me the fuel guys woud be using it.

My Cummins diesel has a 4" pipe all the way back and no muffler. I get up to 28 pounds of boost.
Many guys have tried all sorts of different pipe sizes on these. Anything over 4 in is fine untill you get to the 600 hp/1200 ft lbs range at the rear wheels. Then a 5 in works to advantage. There have been many attempts to make fancy stainless steel "header" for these and none have worked. the stock manifold or the 3 piece replacement are plenty good for this work horse.

Tuned ex is fine for NA but leave it home if you run the blown stuff. The bigger the better.

thrust component from the exhaust?

Funny cars do have tuned exhausts, the pipe, length, bend, and even the angle at which the tips are cut has a LOT of research time and money put into it to tune it for maximum power they're not simply 2 1/2" pipes slapped on there.

Tuned exhaust and scavenging works on any IC engine, it can be NA, supercharged, turbo charged, nitroused, 2 stroke, rotary, etc. The only thing your anecdotes show is that an adequate exhaust pipe diameter is important, which is also very true.

[F-BIRD'88]

The supercharger does the work. The camshaft exhaust timing is different too.

[oldbogie]

Originally Posted by Joe428

So if in the near future I have plans of going blown and or nitrous should I pick up a set of the 1 3/4 long tubes?

A blower hides a lot of sins it also benefits when those sins aren't committed. But the result is probably more for dyno numbers than seat of the pants performance. The average guy will find it easier to tweak the blower output rather than refine the porting. But if you're running on top of the heap and the blower is as tweaked as it'll put up with, anything you can do in the porting to make a few extra ponies can improve payday.

Yes bigger tubes are a must. An easy way to think of this is that the engine thinks it's bigger in displacement by the ratio of blower pressure over atmospheric. So you have to move just that much more stuff through the exhaust. For an in car installation where open tubes aren't used large tube headers are a must. They can be a shorty with a very large diameter collector or long tubes with very large collector as well. the important thing is not to choke the collector diameter down.


Bogie