Is 3" all the way a good thing!!
10-14-2007, 10:34 PM
#7
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Join Date: Sep 2007
Posts: 57
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corky says that your downpipe MUST start at the size of your turbo outlet flange, and should only increase from there at no more than 15 degrees at a time. a sudden change in size, and therefore pressure, will result in a turbulent flow, and therefore more drag, making it less efficent than a smoothly changed diameter pipe.
after that, 3" would be better(no exhaust would be best) but a 2.5" system that is smoother with less restrictions would be better than a 3" system with shitty welds and lots of bends.
after that, 3" would be better(no exhaust would be best) but a 2.5" system that is smoother with less restrictions would be better than a 3" system with shitty welds and lots of bends.
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10-15-2007, 12:47 AM
#11
corky says that your downpipe MUST start at the size of your turbo outlet flange, and should only increase from there at no more than 15 degrees at a time. a sudden change in size, and therefore pressure, will result in a turbulent flow, and therefore more drag, making it less efficent than a smoothly changed diameter pipe.
after that, 3" would be better(no exhaust would be best) but a 2.5" system that is smoother with less restrictions would be better than a 3" system with shitty welds and lots of bends.
after that, 3" would be better(no exhaust would be best) but a 2.5" system that is smoother with less restrictions would be better than a 3" system with shitty welds and lots of bends.
I'm all for 3" as soon as you can get it. To me its the best compromise of size/cost/fitment/sound etc...
On that note... I won't run any turbo car with less than 3" at this point.
Did I mention that the 3" off the turbo and all the way back... is on my beater?
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10-15-2007, 12:50 AM
#12
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Toyota Supras start at 4" downpipes, and they make 5" and even 6" downpipes. You want a 3" downpipe.
BEGI's 2.75" DP starts at 2.25" or so and steps up slowly like Corky talks about to the end size. You can have them make it into a 3" DP at the end for another $30 or so. Order up a 3" Enthuza setup, and the car will be nice and quiet and flow very nicely.
BEGI's 2.75" DP starts at 2.25" or so and steps up slowly like Corky talks about to the end size. You can have them make it into a 3" DP at the end for another $30 or so. Order up a 3" Enthuza setup, and the car will be nice and quiet and flow very nicely.
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10-15-2007, 03:09 PM
#13
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Join Date: Dec 2005
Location: San Antonio
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Avoid turbulence (easier said than done).
Avoid steps and abrupt transistions in size.
Mandrel-bent pipes.
Swage the pipes so pipe inlets fit "over" the previous pipe's outlet.
Avoid sharp turns or protruberances.
Use quality catalytic convertor and muffler.
Reduce backpressure as much as possible after the turbo.
Separate the wastegate flow from the main flow.
Don't forget you have to fit all of that under the car and into the engine compartment. The larger everything is the more likely the exhaust will bang on the frame under cornering or when the engine torques. Mazda Competition's racing motor mounts helped my car significantly.
My system that Corky custom-built for me?
Downpipe entry: 4 inches square area
Downpipe to cat: 4.9 inches square
Mid-pipe: 7.1 inches square
Muffler inlet: 8 inches square
Exhaust outlet: 9.6 inches square
And...he guaranteed me at least one horsepower increase over stock. Pretty good deal in my book....
Barry
PS. I'm still waiting to hear confirmation from Corky about the final details of the Bonneville Streamliner on which he modified the intercooling system. The fellow who ran that Streamliner and another one (the guy makes a good living) at Bonneville set a new class record and, first time at Bonneville, became the 8th fastest human on wheels. Corky does good work.
Now...time for me to get back to work.
Avoid steps and abrupt transistions in size.
Mandrel-bent pipes.
Swage the pipes so pipe inlets fit "over" the previous pipe's outlet.
Avoid sharp turns or protruberances.
Use quality catalytic convertor and muffler.
Reduce backpressure as much as possible after the turbo.
Separate the wastegate flow from the main flow.
Don't forget you have to fit all of that under the car and into the engine compartment. The larger everything is the more likely the exhaust will bang on the frame under cornering or when the engine torques. Mazda Competition's racing motor mounts helped my car significantly.
My system that Corky custom-built for me?
Downpipe entry: 4 inches square area
Downpipe to cat: 4.9 inches square
Mid-pipe: 7.1 inches square
Muffler inlet: 8 inches square
Exhaust outlet: 9.6 inches square
And...he guaranteed me at least one horsepower increase over stock. Pretty good deal in my book....
Barry
PS. I'm still waiting to hear confirmation from Corky about the final details of the Bonneville Streamliner on which he modified the intercooling system. The fellow who ran that Streamliner and another one (the guy makes a good living) at Bonneville set a new class record and, first time at Bonneville, became the 8th fastest human on wheels. Corky does good work.
Now...time for me to get back to work.
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for more than one guaranteed horsepower
10-15-2007, 04:30 PM
#19
Toyota Supras start at 4" downpipes, and they make 5" and even 6" downpipes. You want a 3" downpipe.
BEGI's 2.75" DP starts at 2.25" or so and steps up slowly like Corky talks about to the end size. You can have them make it into a 3" DP at the end for another $30 or so. Order up a 3" Enthuza setup, and the car will be nice and quiet and flow very nicely.
BEGI's 2.75" DP starts at 2.25" or so and steps up slowly like Corky talks about to the end size. You can have them make it into a 3" DP at the end for another $30 or so. Order up a 3" Enthuza setup, and the car will be nice and quiet and flow very nicely.
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10-15-2007, 06:13 PM
#20
Junior Member
Join Date: Sep 2007
Posts: 57
Total Cats: 0
Thanks BEGITechRep and others for stepping in and helping me out. Maximum boost and the BEGI website is fresh in my mind, but since I dont have a turbo yet, I feel like I dont have any real rep points here. when someone starts spouting their HP PSI details at me, ive got nothing to go on, unless they have tried scientific studies with various sized pipes.
i also am aiming for a similar goal as corky's engineering goal, which is the most HP per PSI, not total PSI. once I get my system up and running, then I can start bouncing numbers back when people say "ZOMG, ive got 30 more HP than you running 15 more PSI!!!1"
i also am aiming for a similar goal as corky's engineering goal, which is the most HP per PSI, not total PSI. once I get my system up and running, then I can start bouncing numbers back when people say "ZOMG, ive got 30 more HP than you running 15 more PSI!!!1"
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