Out of curiousity why does everyone use 2.5" on the crossover pipe
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From: Port Tobacco, MD
Out of curiousity why does everyone use 2.5" on the crossover pipe Why does everyone use 2.5" tubing for the crossover in almost every turbo kit done on here for a setup designed for 600-1000hp?
JMO.... but the headers, crossover, merge section need to be sized accordingly based on velocity of the exhaust based on what the motor will do at max boost, peak airflow.
Discuss...
JMO.... but the headers, crossover, merge section need to be sized accordingly based on velocity of the exhaust based on what the motor will do at max boost, peak airflow.
Discuss...
My cross over is 2.25" ID...probably only at the 600 WHP mark at this point but stepping it up this spring to 750 WHP.
I do know that there was a 3" cross over that was tried with a member on here with a T6 large turbo and he has since reduced his pipe to 2.5".
When I did build my hot side, I calculated my cross-sectional areas to keep the volumes of the pipes "equal"
Area of 2.25" ID pipe = 3.97"
Area of a 3" ID piper = 7.065"
If two 2.25" pipes merged into a 3" pipe, they would supply the turbo with less of a pressure/area difference then a 2.5" crossover.
Is this an answer that you were looking for by chance?
I do know that there was a 3" cross over that was tried with a member on here with a T6 large turbo and he has since reduced his pipe to 2.5".
When I did build my hot side, I calculated my cross-sectional areas to keep the volumes of the pipes "equal"
Area of 2.25" ID pipe = 3.97"
Area of a 3" ID piper = 7.065"
If two 2.25" pipes merged into a 3" pipe, they would supply the turbo with less of a pressure/area difference then a 2.5" crossover.
Is this an answer that you were looking for by chance?
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From: Port Tobacco, MD
TracyRR did some testing awhile back....
Ended up going to smaller pipes that worked better in the calculator...
Boost response was better to the point he wanted to put a larger turbine housing on
With the smaller pipes and the larger AR turbine housing the combo made boost down low quicker than the big pipes and the small AR
http://www.yellowbullet.com/forum/sh...=turbocharging
Ended up going to smaller pipes that worked better in the calculator...
Boost response was better to the point he wanted to put a larger turbine housing on
With the smaller pipes and the larger AR turbine housing the combo made boost down low quicker than the big pipes and the small AR
http://www.yellowbullet.com/forum/sh...=turbocharging
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From: Port Tobacco, MD
2.5" crossover will support 2300hp+
So why would you use a 2.5" crossover that will support 2300+hp in a 700hp application?
Velocity can't exceed the speed of sound(11xx FPS) inside the pipe
So why would you use a 2.5" crossover that will support 2300+hp in a 700hp application?
Velocity can't exceed the speed of sound(11xx FPS) inside the pipe
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From: Port Tobacco, MD
My cross over is 2.25" ID...probably only at the 600 WHP mark at this point but stepping it up this spring to 750 WHP.
I do know that there was a 3" cross over that was tried with a member on here with a T6 large turbo and he has since reduced his pipe to 2.5".
When I did build my hot side, I calculated my cross-sectional areas to keep the volumes of the pipes "equal"
Area of 2.25" ID pipe = 3.97"
Area of a 3" ID piper = 7.065"
If two 2.25" pipes merged into a 3" pipe, they would supply the turbo with less of a pressure/area difference then a 2.5" crossover.
Is this an answer that you were looking for by chance?
I do know that there was a 3" cross over that was tried with a member on here with a T6 large turbo and he has since reduced his pipe to 2.5".
When I did build my hot side, I calculated my cross-sectional areas to keep the volumes of the pipes "equal"
Area of 2.25" ID pipe = 3.97"
Area of a 3" ID piper = 7.065"
If two 2.25" pipes merged into a 3" pipe, they would supply the turbo with less of a pressure/area difference then a 2.5" crossover.
Is this an answer that you were looking for by chance?
On my setup the velocity at the throat of the turbo is ~ 1100fps.
I cut up my truck manifolds, and those suckers pinch down to a 2.25"! That's the size crossover I'm running in my 67. 4.5" of exhaust (combined) is more than enough for 1000whp.
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I would vote that if you have 1 5/8" primary tubes that either feed a log or forward mount turbo header, you should use 2.25" cross over that merges into a T4 flange.
If you are upping the ante and have a T6, you should have a 1 3/4" primary (it does make a difference....) to a 2.5" crossover which then will go into the massive T6 flange.
Just my two cents...computed with basic math.
If you are upping the ante and have a T6, you should have a 1 3/4" primary (it does make a difference....) to a 2.5" crossover which then will go into the massive T6 flange.
Just my two cents...computed with basic math.
Ive used 2.25" since you and i talked about almost 2 years ago, and cannot help but think your math was flawless then as i came to a very similar conclusion. 
For the record, i was considering 2 1/8" until i realized how hard it was to find.
Phil= Da man!
Also, on the t6 note, 2.25" pipe squares out perfect to fit inside a divided t6 flange.
For the record, i was considering 2 1/8" until i realized how hard it was to find.
Phil= Da man!
Also, on the t6 note, 2.25" pipe squares out perfect to fit inside a divided t6 flange.
Which formula?
Cross sectional area, I used this formula many many times, each time it seems to be in an exhaust talk, lol
http://www.engineeringtoolbox.com/pi...ons-d_873.html
Cross sectional area, I used this formula many many times, each time it seems to be in an exhaust talk, lol
http://www.engineeringtoolbox.com/pi...ons-d_873.html
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From: Port Tobacco, MD
On a 370", setup to run x275, 88mm turbo, 25# of boost, I'd like to see 1 3/4" stepped headers to 1 5/8. 2 1/8 or 2 1/4 to 2.5" or 2.75" into the turbo. Velocity gradually increases to a max of 1000fps at the turbo. About 400fps at the valve
300-350fps in the header
600-650fps in the crossover
925-975fps in the merge
1050-1100 at the turbo
Out of the turbo is another story. Usually 120% of the exducer and external wastegates is a good start.
300-350fps in the header
600-650fps in the crossover
925-975fps in the merge
1050-1100 at the turbo
Out of the turbo is another story. Usually 120% of the exducer and external wastegates is a good start.
