I am considering headers for my vette and I like the price of the shortys compaired to the full length ones in ceramic. I know the full lengths will help out torque and flow a little better. Will the difference be dramatic in a 383 stroker engine? plus do shortys fit ok?

Tumarr,
I was kicking around with the same dilemma on the forum here awhile back. I went with the full length header over the shorty headers. If you are running a 383 stroker, stick with the full length. Obviously you went with 383 for some serious power. Why stop short now? Wait a little and save up a couple more bucks for the full length. How much of a price difference between the shortys and the long ones?
And that my .02 cents
Sarge

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

For what it worth, the long tube are better overall performance, but will perform much better at lower RPM than the shorty. Very noticable. The shorty is usually easier to install.

Ken Styer

you won't regret the extra expense when you dust off a mustang by half a car. but if you lose by half a car you would have wished you put the longs on

|UPDATED|1/6/2004 5:35:57 AM (AZT)|/UPDATED|


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Have a 383 in my 84. Have dyno tested both short and long tube. Long tube are the way to go and not much difference in cost.

John73

can you post the results?

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For those of us who really don't understand exactly how headers improve performance could someone layout the basics of the issue? Not just long vs. short, but exhaust headers in general. I hate to sound like a complete ingnoramus on this issue . . . but I am!

fun71 said: For those of us who really don't understand exactly how headers improve performance could someone layout the basics of the issue? Not just long vs. short, but exhaust headers in general. I hate to sound like a complete ingnoramus on this issue . . . but I am!

Hey Joe!
I try to keep it simple. Example: Typical small block manifold is just like a pipe w/4 exhaust port openings and 1 outlet. As the engine runs all the exhaust gases are colliding into each other within the manifold which is basically a pipe. And the gases are trying to get out of a small opening onto the exhaust system.
Headers allow exhaust gases to pass through each exhaust ports own separate pipe. So there is no turbulence of gases colliding into each other. And at the collector where all 4 tubes meet into 1 opening. There is less restriction and more of a "scavenging" effect happening. Hope this kinda helps.
Sarge

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

To continue that a bit, an object in motion tends to stay in motion. When the exhaust is traveling out of the cylinder, it's moving fast. Then the exhaust valve slams shut. Now the gas keeps moving, but has no supply. This creates a vacuum pulse in the exhaust system everytime a valve shuts. Headers allow the exhaust to flow evenly and faster with the less backpressure and smoother flow path. This makes the exhaust to flow faster. This creates a greater vacuum. When the header pipes come together at the collector, the vacuum created by one pipe creates vacuum on the other pipes. This sucks more exhaust out of the cylinder when the next exhaust valve opens. With the increased volocity the cylinder empties more, allowing more fresh air fuel mix in to the cylinder, creating more power. Each one helps the next. If the headers are too big for the engine, you lose the effect due to the larger size slowing down the flow. Much as a slow moving river compared to a narrow spot that flows faster. If it's restricted too much, it also slows down the flow and leaves WAY to much in the cylinder.
The term tuned headers mean the header pipes are all the same length and volume. They work better than shorty untuned headers. The shorty is better than stock manifolds.

Ken Styer

I really appreciate the education guys! I just have two last dumb questions.

1. What are the best headers for a '71 LS5 454? I assume long? Or ??
2. If headers have such a significant effect on performance, why are they not used more often as "standard equipment" ??

Long headers are always better.
The factory does not put them on partly due to cost, part due to space limitations, part due to assembely limitations, part due to emissions. Plus most people don't know the difference, or care. We do.

Ken Styer

i installed hooker super competition long tube headers on my 74 ls4 454, made a world of difference, if you're really looking for an improvement, i'd definitely recommend them.

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i installed hooker super competition long tube headers on my 74 ls4 454, made a world of difference, if you're really looking for an improvement, i'd definitely recommend them.

I'm glad to hear that. I'm having the same ones installed on our 74.

diameter of the tubes is also very important. as stated above too large of a diameter will lessen the scavaging effect and hurt low end power, too small diameter will increase low end power at the cost of high RPM power. I suggest to error on the smaller size as most driving is done at lower RPM

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What is the correct pipe diameter for a high compression 350?


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'69 350/350 conv.

1-5/8" diameter for low HP 1-3/4" for higher HP. I wouldn't go any larger than 1 3/4

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