Header collector size

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joes68340s

joes68340s

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Has anyone experimented with collector diameter. Like running 3 inch collectors and then running 2 1/2 collector extensions. Any idea if it would make a big difference in ET or mph. I ask because a friend bought a Drag car and that was how it was set up. We wondered how much it would slow it down.
 
Depends on the combo,there is NO proper answer to this question.
 
Use the same size pipe as the header is for this distance.

Paint them make a pass then cut them off at the burn mark. Should be between 18 to 24 inches. Add a cross over mid way. You will see a difference. This is not done for cars with Boost.
 
Ah the ol' paint the collector extension myth. The only thing one will find doing that is the paint's thermal resistance. To answer your question extension length / diameter is combo specific. Years ago I went from 2.5" exhaust to 3" exhaust and knocked off nearly 3 tenths on a high 12 sec car. That being said I don't doubt the 2.5" extensions are helping your friends cause.
 
joes68340s said:
Has anyone experimented with collector diameter. Like running 3 inch collectors and then running 2 1/2 collector extensions. Any idea if it would make a big difference in ET or mph. I ask because a friend bought a Drag car and that was how it was set up. We wondered how much it would slow it down.
Click to expand...

If you are serious about getting the right length for your engine combo, you need to buy this software.

http://www.maxracesoftware.com/PIPE39.htm

PipeMax is designed to predict proper header length, diameter and collector length.
PipeMax is a grate program

But there is many other freebies that come with this program.

It's well worth the money. if not........the - "paint and cut" - is as close as you will ever get.
 
This isnt about length it was diameter. Since the car came with a 2 1/2 collector ext, I was wondering if it could have been used for a tuning method, such as trying to slow car down a little to fit into class. It was done for a perpose since it had the evac lines attached. Just wondering if anyone has done something like this.
 
joes68340s said:
This isnt about length it was diameter. Since the car came with a 2 1/2 collector ext, I was wondering if it could have been used for a tuning method, such as trying to slow car down a little to fit into class. It was done for a perpose since it had the evac lines attached. Just wondering if anyone has done something like this.
Click to expand...

Maybe to get more vac out of the evac. smaller pipe, more velocity= more pan evacuation:dontknow::dontknow:
 
joes68340s said:
This isnt about length it was diameter. Since the car came with a 2 1/2 collector ext, I was wondering if it could have been used for a tuning method, such as trying to slow car down a little to fit into class. It was done for a perpose since it had the evac lines attached. Just wondering if anyone has done something like this.
Click to expand...

The increase in velocity through the 2.5 may actually increase the performance due to the scavenging effect.
Don't know for sure, but it's possible.
 
my 2 cents,

Hit it hard, chop it, get it stopped quickly and use an infrared thermometer to find the hot spot on your extension tube. Start about 18" back. The spot where you have the highest reading is likely to be very close to your best length.

Seen a bunch of people use smaller extensions than the collector sizing to tune for an outcome.
 
I'm curious to know what car, engine size and combo he's running? Look at some of the 40yr old, little engine stock/superstock and even mod eliminator type cars. Some guys used smaller diameter and long collectors to try and build a little more torque on engines that virtually had none.
 
That makes sense as that is what I believe the car was. 71 Duster 340 727, 4.88. Recently installed tti headers with the 2 1/2 dia collectors. runs 11.50-11.70s. Not a real fan of the tti.
 
hi, what size are the primary pipes? they small or large? collector dia will depend on their size.its the total package.
 
TTI 1 5/8 to 1 3/4, 3 inch collectors with 2 1/2 header extension. Not a TTI header fan.
 
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