Oval Tubing Exhaust
07-21-2018, 02:03 PM
#2
Instructor
I am not sure of who has made one but I know dr gas products has most of the tubing. I was researching them a few years ago when I was prepping a circle track car. Is this for a street car or track only?
07-22-2018, 03:06 PM
#6
I have made exhausts systems and am looking forward to making one for the 944. I was hoping someone had a list of bends needed, especially for the turbo down pipe. Also if someone has made an oval exhaust before what they liked or disliked about it. In the past oval was a rare tubing and I had the number of one of the few tubing companies that offered, manufactured oval tubing. Another local fabricator used it to reinforce 356's and he even put 944 front suspension on a few.
Today you can get oval from burns of course but also vibrant and everyone else either makes it or retails it... summit...jegs.. very common in stainless. my thought was to use it as part of the crossover and from the down pipe back in like 3.5in.
Anyone have thoughts on how the size would compare, seems like many of the large diameter exhausts are just large near the muffler and smaller near the turbo. This is nearly opposite of talley cars or really any other exhaust system I have seen and although there may be a small decrease in back pressure as the exhaust gas cools so does the velocity and therefore its ability to add significantly to the back pressure.
Seems like with oval we could make a large high flowing exhaust while maintaining some reasonable ground clearance.
Today you can get oval from burns of course but also vibrant and everyone else either makes it or retails it... summit...jegs.. very common in stainless. my thought was to use it as part of the crossover and from the down pipe back in like 3.5in.
Anyone have thoughts on how the size would compare, seems like many of the large diameter exhausts are just large near the muffler and smaller near the turbo. This is nearly opposite of talley cars or really any other exhaust system I have seen and although there may be a small decrease in back pressure as the exhaust gas cools so does the velocity and therefore its ability to add significantly to the back pressure.
Seems like with oval we could make a large high flowing exhaust while maintaining some reasonable ground clearance.
07-22-2018, 03:11 PM
#7
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07-22-2018, 03:53 PM
#8
Drifting
Now with the upper one piece double pipe flange would work great at it’s intended location as the start of the twin scroll crossover but not under the pan. Not enough room.
How about make a two piece twin scroll crossover with a twin waste gate setup? Possibly make the crossover turbo mount go to a twin scroll GTX or similar turbocharger? Maybe use a v band clamp at the turbo and a one piece flange holding both crossover pipes at the two pice intersection(like the LR crossover mod but with two pipes, the best would be using a flat face double pipe flange like that found on the lower LR headers and using the same style flange but with O-rings groved like that found on the later crossovers at the header collector). Then use the oval tubing as a heat shield to hide your treasure and help with heat protection between the oil pan and crossover. Then use the oval tube from if you still think you need it from the bottom of the turbo downpipe out.
07-22-2018, 05:01 PM
#9
Rainman
Rennlist Member
Rennlist Member
as you know oval tubing is available but its retardedly expensive.
super easy to just get round tubing in the flow diameter you need and squish it a little on a press to make an ellipse (support the inside)
or you can lay it on the ground, put some wood on either side of it (stacked lower than the tube diameter) and drive a car over it. the wood stack height determines the "squish dimension" as the car weight will squish the tube down until the tire rests on the wood instead of the tube...seriously works well, have done this recently lol
super easy to just get round tubing in the flow diameter you need and squish it a little on a press to make an ellipse (support the inside)
or you can lay it on the ground, put some wood on either side of it (stacked lower than the tube diameter) and drive a car over it. the wood stack height determines the "squish dimension" as the car weight will squish the tube down until the tire rests on the wood instead of the tube...seriously works well, have done this recently lol
08-02-2018, 05:24 PM
#10
you know its a good point about just squeezing it. i have done this before to clear things but didnt really think about it for a larger section.
On the twin scroll thing. Is there a big advantage?
I am still planning my rebuilt and trying to get everything decided before hand. So i have not worked on the exhaust yet. But having just replaced turbo thing.
On the twin scroll thing. Is there a big advantage?
I am still planning my rebuilt and trying to get everything decided before hand. So i have not worked on the exhaust yet. But having just replaced turbo thing.
08-02-2018, 06:12 PM
#12
Rainman
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it should have the same CSA and diameter as the original round pipe but taken to extremes the change in shape could affect how neatly the air flows through the tube.
so going up to the next incremental size, if available, is a good solution.
so going up to the next incremental size, if available, is a good solution.
08-03-2018, 12:48 AM
#13
Drifting
I think so. But it cost a bit more for our cars due to supply and demand. It has to do with keeping the exhaust pulses separated so they don’t overlap each other like a 4/2/1 exhaust setup, like the stock exhaust is on a 951. So 1/4 and 2/3 exhaust pulses are paired up because they don’t overlap which creates high exhaust back pressure at higher RPM’s. The advantage is faster spool up times and the chance of exhaust reversion is dramatically reduced is what it boils down to. It’s something to research yourself and see if it’s right for you. In most cases the stock setup is fine. But for those who take it to the next level regarding the exhaust manifold to the turbo on four bangers like to use twin scroll turbo setups.
08-03-2018, 05:30 AM
#14
Addict
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