Boiler2
20+ Year Contributor
- 149
- 1
- Mar 9, 2003
-
Lancaster,
Pennsylvania
I am posting this thread for all those people having boost creep problems on the EVOIII 16G turbo.
My mod list is up to date and if you notice I have a ported 2G O2 housing and full 3 turboback exhaust. I bought my EVO3 from SBR back in Sept of 2003. It has the 34mm flapper mod.
I installed it in early Oct of 2003. In the process, I ported my 2G exhaust housing exit to match the already ported 7cm turbo housing done by SBR. It is true about what you read about the 2G O2 housings not exactly matching the SBR EVO3 turbo housing exit. The bolt holes match up though, which is all you need because you can port match the rest.
After the initial install, I could not run less than 22ps,i which is not too good on pump gas for me because I saw a bad timing curve. Sometimes it would creep to 24 psi. I disconnected the boost controller and it would pause at 11psi(stock wastegate pressure) then rocket to 22 and hold there. And I knew colder weather was coming which could cause more problems (I am in the South, but from the North).
Thinking about how to control boost creep it is all about the air following the path of least resistance, which in my case was through the turbine wheel and out which caused me boost creep and more boost than I wanted.
I then dropped the turbo and ported the hell out of a few things. First, I drastically cut back the divider in the O2 housing to make the exit wastegate path larger. I had already ported the exit of the O2 housing so that was left alone. Second, I ported the O2 housing inlet side to match the turbo exhaust housing. Third, I ported the step at the bottom of the turbine housing wastegate area. This is where the air coming out of the wastegate hole practically hits a perpendicular wall and then has to flow out. I simply removed this so the air exiting the wastegate hole hit more of a curves wall then out to the O2 housing. Then I put everything back together and started it up.
After a few settings, I still had boost creep but it was only ever to 20psi, which is a little better on pump gas but not where I wanted to be. Then it got colder (November) and I started having serious creep back to 24psi. So it was time for plan B.
I dropped the turbo again and this time ported the wastegate hole on the turbo slightly making sure I would still get a good seal with the flapper. The other thing I did was from a vfaq I saw. I ported a step in the 7cm housing area so the air would flow towards the wastegate hole better when it opened. If you looked down into the 7cm housing, I ported it so you could see the flapper door easily. I removed a good bit of material. That was it so I again put everything back together.
I turned the boost down and to my surprise, it held at 14psi which is where I set it. I could go lower to the stock spring setting but that was good enough for me. I now run a happy 18psi on pump gas and it holds perfectly with no more timing retard from high boost levels. I have run a 7.81 at our local 1/8th mile track @ 83mph. (our track is 60 feet shorter than a true 1/8th mile dont ask). This should be good for mid to upper 12s on a true ¼ mile.
Sorry I do not have any pictures, but you can email questions and I can try to answer. Thanks.
My mod list is up to date and if you notice I have a ported 2G O2 housing and full 3 turboback exhaust. I bought my EVO3 from SBR back in Sept of 2003. It has the 34mm flapper mod.
I installed it in early Oct of 2003. In the process, I ported my 2G exhaust housing exit to match the already ported 7cm turbo housing done by SBR. It is true about what you read about the 2G O2 housings not exactly matching the SBR EVO3 turbo housing exit. The bolt holes match up though, which is all you need because you can port match the rest.
After the initial install, I could not run less than 22ps,i which is not too good on pump gas for me because I saw a bad timing curve. Sometimes it would creep to 24 psi. I disconnected the boost controller and it would pause at 11psi(stock wastegate pressure) then rocket to 22 and hold there. And I knew colder weather was coming which could cause more problems (I am in the South, but from the North).
Thinking about how to control boost creep it is all about the air following the path of least resistance, which in my case was through the turbine wheel and out which caused me boost creep and more boost than I wanted.
I then dropped the turbo and ported the hell out of a few things. First, I drastically cut back the divider in the O2 housing to make the exit wastegate path larger. I had already ported the exit of the O2 housing so that was left alone. Second, I ported the O2 housing inlet side to match the turbo exhaust housing. Third, I ported the step at the bottom of the turbine housing wastegate area. This is where the air coming out of the wastegate hole practically hits a perpendicular wall and then has to flow out. I simply removed this so the air exiting the wastegate hole hit more of a curves wall then out to the O2 housing. Then I put everything back together and started it up.
After a few settings, I still had boost creep but it was only ever to 20psi, which is a little better on pump gas but not where I wanted to be. Then it got colder (November) and I started having serious creep back to 24psi. So it was time for plan B.
I dropped the turbo again and this time ported the wastegate hole on the turbo slightly making sure I would still get a good seal with the flapper. The other thing I did was from a vfaq I saw. I ported a step in the 7cm housing area so the air would flow towards the wastegate hole better when it opened. If you looked down into the 7cm housing, I ported it so you could see the flapper door easily. I removed a good bit of material. That was it so I again put everything back together.
I turned the boost down and to my surprise, it held at 14psi which is where I set it. I could go lower to the stock spring setting but that was good enough for me. I now run a happy 18psi on pump gas and it holds perfectly with no more timing retard from high boost levels. I have run a 7.81 at our local 1/8th mile track @ 83mph. (our track is 60 feet shorter than a true 1/8th mile dont ask). This should be good for mid to upper 12s on a true ¼ mile.
Sorry I do not have any pictures, but you can email questions and I can try to answer. Thanks.
I dont. BTW what track are you referring to? Irvington?
))
