What wastegate mm are you 1UZ turbo guys using?

XR8tt

Moderator
Maybe...LOL. Just kidding. I never read the Corky book, it's what I have built on my SC. Or maybe the idea came from other sources and somehow it got into my mind. You know that no single human being could actually create anything from A-Z, he/she just learned from other sources and put them together.
Hope you didn't get it the wrong way??
I was complimenting...
Its the same with log style turbo exhaust manifolds ..
People often bag them, but built with close to 45* as above
they flow quite well...
 
To big or a gate will cause boost creep cause they barely open to divert flow. Remember, a WG uses both boost and exh. pressure to open the valve. If the flow that it is trying to control is so small that it over controls that flow cause the cracking point offers more then enough flow to contol that the particular amount of flow and thus boost, it will shut and thus allow boost to to slighly rise and try again. What ends up happening is that the valve flutters and causes boost creep. I had the same problem a while ago on my supra and was running a HKS 50mm gate at 8psi and it would slowly creep to about 12 in about 2 to 3 seconds. After logging a run through all gears I saw that once I hit 8psi, it would drop about a 1/4psi then rise about 1/2, then drop about a 1/4 again and rise about another 1/2 and so on until about 12psi where it would stop. It was happening so fast that all you would see was a slow rise on the gauge but in the datalog you could see the fluttering..... I upped to boost to about 14 and and it would rise as normal and stay at 14 all day long no more WG flutter and no creep beyond that point. I changed back down to a 40mm HKS unit and there was no creep at 8psi like there was with the 50mm.

The other thing that is can cause boost control problems with external gate is there placement in relationship to exhause flow path in the manifold. Poor placement of the gate will cause similiar issues. Any time you limit flow to the gate (i.e. at a right angle to the flow path or where it is only seeing a cylinder or two of flow), it will have a hard time controling boost.
Very interesting reading...Thank you
 
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