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Forum nameTurbo/Nitrous Tech
Topic subjectWastegate Pipe Length?
Topic URLhttp://forums.2gnt.com/dcboard.php?az=show_topic&forum=8&topic_id=108871
108871, Wastegate Pipe Length?
Posted by Progress, Dec-31-69 06:00 PM
I am getting tired of my atmospheric dump on my external wastegate so I am going to have the dump pipe welded into the exhaust... Now, my question is, what is the overall difference in how long you have the dump tube before it enters the exhaust, I have seen alot of track use cars that have about a 2'-2 1/2' length of dump pipe, most street cars have the dump tube enter the exhaust about 6inches from the downpipe flange, and some are welded straight on at a 90degree angle and some at a 45degree angle, almost like it would cause a vacume to help pull the exhaust out of the wastegate faster. Is there any overall difference in any of this or is it just a matter of taste/setup?
108917, RE: Wastegate Pipe Length?
Posted by Dstach, Dec-31-69 06:00 PM
All I would see is the 45 has a better flow that the 90. Personally I would use a gradual like a 45 if I wanted to pipe it into the exhaust but I'm doing atmospheric dump on my build.
108918, RE: Wastegate Pipe Length?
Posted by DarkOne, Dec-31-69 06:00 PM
The more gradual the angle, the less turbulence at the point the bypassed gases enter the main exhaust.
108938, RE: Wastegate Pipe Length?
Posted by Progress, Dec-31-69 06:00 PM
Thank you for the info, I already had my dump pipe welded back into the exhaust before the replys, but again thank you for the responce. On that same subject, the guys at the local speed shop who build some seriously high horsepowered motors, v8's mainly, turbo and NA, gave me a reason why you will find most race use cars with dump tubes welded back into the exhaust, are welded further down the exhaust on "purpose"... It is because the velosity of the exhaust gasses comming out of the exhaust side of the turbo just as it enters the downpipe on a high horsepower/high boost setup, causes too much of a vacume and can actually draw more exhaust through the wastegate from the manifold than what there is suppose to be exiting and can cause a surge in boost, lag time in spool, and even boost creep due to vacume, and thats because the exhaust velosity 3feet from the hotside of the turbo vs 4-6 inches from the hotside, is almost half of what it is comming directly out of the hotside... But he said that is normally not an issue for someone under 25psi or not running a high displacment motor.. So placing the dump pipe anywhere on the downpipe with my 2.slow and otherwise dinky 50trim on 12psi should be fine. And I say dinky because compaired to this polished 116mm honker they had bolted to this Camaro, mine is dinky!
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