509whp / 357wtq @ 15psi
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From: Chiswick
Originally Posted by candymanjl,May 9 2009, 02:34 PM
I know that with the full-race manifolds they used to have a lot of boost creep problems until they changed the manifold design. the newer full-race manifolds flare out the section going into the wastegate so it's easier for the air to bypass the turbo when the wastegate is open.
it makes sense, before it was a simple pipe off the manifold at a 90 degree angle. air doesn't like to change direction all of a sudden, it wants a gradual turn, that's why ram horn setups gain power on the intake side. with a sharp 90 degree the air is more likely to fly right past the opening to the wastegate and continue to the turbo than exit the wastegate and bypass the turbo.
I'm sure the turbo itself gains momentum and can boost creep on it's own but I believe the manifold and wastegate play into the boost creep problem more than the turbo itself. Tial wastegates are great, heck my buddy had a chinese knockoff ebay one that worked amazingly well, so I doubt it's the wastegate. I'd
bet money that the manifold itself needs to be tweaked similar to how full-race tweaked theirs.
it makes sense, before it was a simple pipe off the manifold at a 90 degree angle. air doesn't like to change direction all of a sudden, it wants a gradual turn, that's why ram horn setups gain power on the intake side. with a sharp 90 degree the air is more likely to fly right past the opening to the wastegate and continue to the turbo than exit the wastegate and bypass the turbo.
I'm sure the turbo itself gains momentum and can boost creep on it's own but I believe the manifold and wastegate play into the boost creep problem more than the turbo itself. Tial wastegates are great, heck my buddy had a chinese knockoff ebay one that worked amazingly well, so I doubt it's the wastegate. I'd
bet money that the manifold itself needs to be tweaked similar to how full-race tweaked theirs.
From doing research on my car with logs and my exhaust cutout, i found that my 44mm Tial (full-race v.2) with the stock exhaust, (cutout closed) i was able to control boost to about 7-8psi (7 psi spring). All tests were done with the boost controller off. With the exhaust cutout open, that same boost pressure increased to about 10-11 psi. The only change in the system was more back pressure post turbo. This means that the system became more efficient and in doing so, made the pressure differential between the wastegate and the Downpipe less. This means that the exhaust gas wanted to flow through the turbo, instead of going through the wastegate, and in doing so, increased boost.
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From: Around
Originally Posted by s2kswe,May 9 2009, 02:59 PM
Yes I am also completely sure of that the characteristics around creep is decided by the manifold to the biggest extent. And as Candy says, the angle of the direction change for the air is very much affecting these characteristics.
Then the WG size will play a role if it cant flow enough gas with a low delta P, but thats another thing that comes after the actual manifold design.
I had no creep with the ILP cast mani and 38mm WG.
On my current design I will have some creep but i plan to regulate the boost above the creep value so the creep wont be "seen".
Then the WG size will play a role if it cant flow enough gas with a low delta P, but thats another thing that comes after the actual manifold design.
I had no creep with the ILP cast mani and 38mm WG.
On my current design I will have some creep but i plan to regulate the boost above the creep value so the creep wont be "seen".
Wastegate design is a HUGE part of it, when I referenced the 30r, I should have been more specific. It is b/c the turbo spools so fast..and causes the issue to show itself.
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From: Around
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