Don Terrill’s Speed-Talk

On my car bracket race I have had several exhaust set ups. Nothing made a huge difference track testing but I was curious about what effect different set ups have. I bought 4-2-1 collectors with race bullets at a swap meet off a sprint car header. Tried those sounded nice but no noticable gain from standard 4-1 collectors. Then I used my 4-1 collectors and put longer pipes on that exit by the rear wheels with a 3" x pipe. It changed the sound of the motor completely. Sounds like I'm reving it to 10K when I'm only shifting at 6500. It sounds really cool and people are always asking about it, but again it was a minimal if nothing on track gain. Obviously it changed something with the tone of the engine but why no results in et? I was wondering what is causing the change. An older guy asked me if I had 180deg headers on my car? Never heard of it but he says thats how they sounded years ago.

Header tube size has a direct effect on the engines performance.
Different tube sizes and even a stepped tube size can produce dramatic gains in power and its more effective on lower HP engines with small port sizes and volumes.Bigger is not always better.
Many years ago I found on some limited engines guys had they responded very well to small tube size and longer tube length.
1 engine that used a dyno style header with 1 3/4" tube 34" long made an extra 55 Hp and 50 Ft/Lbs going to 1 1/2 ' stepped to 1 5/8" tubes same length.

The x pipe does a good job at, in very short terms, splitting up each exhaust pulse and sending an uneven portion of each pulse down each pipe after the x. With the x you are hearing in effect double the exhaust pulses of a split exhaust, so it 'sounds' like the engine is pulling a lot more rpm. It's not as cut and dried as that, but thats the basis of the 'higher rpm' sound from the x pipe setup.

I get the same comments on the sound of my car. It has a Dr Gas X-pipe and mufflers. Engine is a 374CI (4.125 x 3.5). People come up to me after a run (autocross) and always ask about the unique sound.

People usually ask me what gears I'm running or what I'm shifting at. Kind of funny. It is a unique sound for sure.

We did one of the first X pipes in our Trans Am Javelin
funny watching the Ford guys sneaking a peek under the car
The really can sound different
and we thought helped torque off the corner and we could make the exit pipes smaller for ground clerance

wyrmrider wrote:We did one of the first X pipes in our Trans Am Javelin
funny watching the Ford guys sneaking a peek under the car
The really can sound different
and we thought helped torque off the corner and we could make the exit pipes smaller for ground clerance

x or h both allow smaller exit pipes, shared/smoothed exhaust flow they both achieve in slightly different ways allows this.

cgarb wrote: An older guy asked me if I had 180 deg headers on my car? Never heard of it but he says thats how they sounded years ago.

I had some 180 degree headers on my dragster. Real bundle of snakes but it sounded like a Formula 1 car.
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cgarb wrote:On my car bracket race I have had several exhaust set ups. Nothing made a huge difference track testing but I was curious about what effect different set ups have. I bought 4-2-1 collectors with race bullets at a swap meet off a sprint car header. Tried those sounded nice but no noticable gain from standard 4-1 collectors. Then I used my 4-1 collectors and put longer pipes on that exit by the rear wheels with a 3" x pipe. It changed the sound of the motor completely. Sounds like I'm reving it to 10K when I'm only shifting at 6500. It sounds really cool and people are always asking about it, but again it was a minimal if nothing on track gain. Obviously it changed something with the tone of the engine but why no results in et? I was wondering what is causing the change. An older guy asked me if I had 180deg headers on my car? Never heard of it but he says thats how they sounded years ago.

thats a 180 header.

http://youtu.be/-f6VZKolGQs?t=4m42s
https://www.youtube.com/watch?v=MSZTbR6C6Lw

makes it sound like
an engine that actually has a 180 crank
http://youtu.be/rQEL_4MkoNQ

For 180* headers, on a standard firing order small block chev 18436572 what primary tubes get routed together? or does it work better with a 4/7 or a 4/7+2/3 swap cam?

Bob Hollinshead wrote:For 180* headers, on a standard firing order small block chev 18436572 what primary tubes get routed together? or does it work better with a 4/7 or a 4/7+2/3 swap cam?

Well "180" headers are 8 tubes going into 2 4into1 collectors. The way you do it is to have each cylinder in the firing order go into alternating collectors. The result is a even 180 degrees of crank rotation that each collector sees a pressure wave. it is not easy to keep short enough on modern high rpm engines so you do not see them.

Firing order makes no difference.

Now a 8into4into1 header is a bit different, but a different question.

englertracing wrote:

cgarb wrote:
makes it sound like
an engine that actually has a 180 crank

Not only does it sound like and engine with a flat crank, the engine runs like it has a flat crank in it...

this makes it a little easier to set up the 180 headers for high rpm use

englertracing wrote:

this makes it a little easier to set up the 180 headers for high rpm use

Ha , sure does.

on a sbc you'd make the four center cylinders (3-5-4-6) primary header tube cross over to the other cylinder bank's collector.

... Use the stock firing order for this.