That's it. It's starting to look better already

 

Honda-guy, that is more or less what we have been doing for the last 12 years to fix this issue. I would focus on it a little higher up and then cut back in sharper but its getting there. Opening up the actually outlet into the O2 dump was needed (which you already did) as well.

aaron

 

Yeah. That is the right area. Think axial flow path. Exhaust enters the turbine inlet area and is flowing straight through. So, you have to divert, or start to redirect some of that flow into the right angle bypass passage. The entrance radius that the flow hits first is the only important radius. Once axial flow of the exhaust gas through the turbine inlet gets past the center line of the bypass port...it ain't coming back and it ain't gonna make a sharp right turn. So do more work on easing the radii of the leading edge that the exhaust flow contacts. Bring it down more. Feather the entry radius even more.

 

since you've had a lot of first hand experience with this, what's the success rate have you seen from this kind of porting, like how much boost creep were you able to drop? thanks

 

The more that I look at that last pic that you have posted the more that I notice the telltale signs indicating that you did not gasket match at the turbine inlet. There appears to be a shadow where the exhaust gases have left a 1/4" darkened edge on at least one of the sides. It looks like a pretty major mismatch at the inlet mounting flange interface.

 

^ I did not gasket match, just port match and clean the casting. The gasket is significantly larger than the ports on the mani and turbo. Like I said, I didn't want to cut too much materials away since this is a track car, and also the reason why I don't use tubular manifold. I do 30+ track days a year.

 

Yup. I see it clearly in pic #5, 0f your post #63 of this same thread. Both of the twin turbine inlet areas need a lot more material removed out to the gasket line before you can say that you have ported the inlet (s). Are you runningthe factory gasket?

There should not exist a misalignment of this magnitude at that interface between manifold exit flange opening and turbine inlet flange opening. The factory gasket is true. The inlet needs to be gasket matched.

What do you mean that the mismatch will help you in road racing? You lost me there. A mismatch is a mismatch. Call a spade, a spade.

 

hmm this has me thinking to about wat u just said sparky...hondaguy- did u reuse the oem one or did u use the one from fp that came with the install kit? o and where in PA u from? i'm from state college area.

 

I'm using oem gasket. I'm not concern about hogging out the mani or turbine housing as much as port matching. I removed enough materials to match the ports. Porting service without the manifold to match up isn't necessary good.

 

yo where in PA u at?

 

FB doesn't not come with install kit or gasket. I have evo 9 and don't need install kit.

I'm in the Carlisle area

 

yea i had to get the install kit. i wonder if thats my issue. or do they not port the inlet of the turbine housing?

 

You should see casting marks if they didn't port it. But if you got the porting option, then they ported the inlet for sure, but not sure if they port the waste gate ports though, that's the question.

 

i had the porting option done, but wouldnt they send a new gasket to fit that inlet if it changed ne. thats wat im wonderin now.

 

EDITED: A repeat post. Sorry.