internal vs. external waste gate question.
Thread Starter
AudiWorld Member
Joined: Dec 2003
Posts: 429
Likes: 0
internal vs. external waste gate question.
what are the pros and cons of both? i can see that internal is alot easier for fabrication, but is there a gain from one to tne other, also does an external need any tuning or tweeking? thanks
AudiWorld Senior Member
Joined: Mar 2000
Posts: 1,173
Likes: 0
Re: internal vs. external waste gate question.
Internal wastegates are a fixed size. Generally suit smaller turbo chargers.
On larger ones, they have not got the room to make the wastegate big enough to fit in a small exhaust housing, so what you may find is you will suffer from Boost Creep.
On larger ones, they have not got the room to make the wastegate big enough to fit in a small exhaust housing, so what you may find is you will suffer from Boost Creep.
New Member
Joined: Aug 2005
Posts: 343
Likes: 0
Boost creep is no longer a problem. ATP sells a GT3076R WG Turbo
Good for 500hp and internally wastegated.
They've had very good results with it.
And you don't have to mess with a $400 external wastegate and additional labor to get to 500hp.
Less work, less $.....Sounds good to me
They've had very good results with it.
And you don't have to mess with a $400 external wastegate and additional labor to get to 500hp.
Less work, less $.....Sounds good to me
AudiWorld Super User
Joined: Mar 2000
Posts: 13,200
Likes: 2
Boost creep is part of the tuning, so as long as the tuner anticipates it, the problem is controlled
But as Lucas pointed out, external will always have better control or elimination of boost creep. This is because the more expensive valves pop open vertically, not hinged as in an external wastegate. The hinged gates (imagine a trashcan lid opened by a foot lever), will always have uneven opening area as they start to open. This crack is what is anticipated to minimize severe boost spikes. For example, if you want the turbo to start opening around 10 psi, you might want to start applying pressures around 6 (called crack pressure) to an internal wastegate so that by the time the gate is open enough, it's around 10. FOr a good external gate, you can almost just let it open at 10, or a smaller value closer to 10.
AudiWorld Super User
Joined: Sep 2003
Posts: 3,931
Likes: 0
Boost creep is a part of BAD TUNING not good tuning
Boost creep means you cannot get enough air to the WG to bleed boost. Once it starts there is not a cure except to have the WG bleed more. I understand that internal WG cars are notorious for this when the turbo is large. I go to ext. WWG 1st thing so I cant say I have experience with them, but only cure in a ext. WG car is a smaller turbo or a bigger WG. I would never pay for a chip where boost creep was a part of the programming, why would anyone allow it?
Rod
Rod
AudiWorld Super User
Joined: Mar 2000
Posts: 13,200
Likes: 2
But since boost creep is essentially an artifact of most internal WG designs,
if the tuner is not careful to program the duty cycle control with respect to boost demand and the rising RPMs, then there is a danger of getting massive boost spikes and/or boost creeping upwards until the internal wastegate is open large enough such that the turbine slows down. That's my point about the boost creep and the tuning, or the need to attend to it. I won't be surprised if some kits out there had initial problems because of detonation - from boost spikes and from ignoring boost creep
Thread
Thread Starter
Forum
Replies
Last Post
quattrorally
A4 (B5 Platform) Discussion
0
May 24, 2007 07:20 PM
3fordasho
Audi Original "S" Cars
7
Nov 16, 2006 11:45 AM
zhenya
S4 / RS4 (B5 Platform) Discussion
2
May 17, 2005 04:45 PM
