Drilled Exhaust Housing Divider, Lower Boost

[PKirby]

I have noticed I can't make as much boost with my new hybrid as with my old WH1C. I can't get over 28psi and I could hit 30 easy with the WH1C. when I added the hybrid, also added a 3k GSK and drilled the divider on the exhaust housing with a 9/16" bit. I am using the same 12cm housing from the old turbo and did not change any actuator settings.

I thought with the GSK and the new Super 40 wheel and housing the divider would need to be drilled. On my exhaust manifold type (4-2 split), only 2 cylinders were being wastegated.

 

[Forrest Nearing]

2psi difference isn't much. you might need to play with the wastegate setting... try pinching off the line and see what you get... then go from there with whatever boost level you're comfortable with

 

[PKirby]

It didn't have a boost elbow. I thought I had installed one back when I put the used eBay #6 plate in. It was just a plain brass elbow. I installed an adjustable needle valve and now the boost spikes to 35psi quick instead of slowly to 28. I slipped the clutch for the first time today in 5th gear.

 

[mattymac]

Just remember more boost doesnt mean more power, Its just a measure of restriction, depending on your setup you can flow more CFM at a lower PSI

 

[Forrest Nearing]

depending on your setup you can flow more CFM at a lower PSI

how? other than porting the head or a different camshaft of course...

 

[PKirby]

I am not sure if it has that much more power after the needle valve install, but it comes in a heck of a lot quicker. I liked it but my LUK clutch didn't.

 

[Jim Fulmer]

Didi you drill out the devider under the wastegate flapper? if so then when the gate openes it vents all 6 cylinders!



My old HX-40 does this too and holds about 35-36 psi on a truck that did 440 on #2 only, if it didn't have this mod it would pop that turbo without a doubt.



Jim

 

[PKirby]

Didi you drill out the devider under the wastegate flapper? if so then when the gate openes it vents all 6 cylinders!



My old HX-40 does this too and holds about 35-36 psi on a truck that did 440 on #2 only, if it didn't have this mod it would pop that turbo without a doubt.



Jim

Yes, I drilled the center divider. That must make a fairly bid difference because the old WH1C with the same exhaust housing before being drilled could make 30psi. Same drilled housing on the hybrid could only make 28 and built the boost from 20 to 28 more slowly. All of this was without a boost elbow.

 

[dpuckett]

Check your system for air leaks. WHen you took it all apart, you could have gotten something not quite up to snuff, and have a leak now.



Daniel

 

[BPonci]

It might be possible that since your gating all 6 cylinders that there is more surface load on the flapper and its creeping open. You might try a little more preload on your w/g arm.

 

[PKirby]

It might be possible that since your gating all 6 cylinders that there is more surface load on the flapper and its creeping open. You might try a little more preload on your w/g arm.

I have the actuator set at 3/16" shorter than closed. I was thinking about adding a spring and an adjustable eye bolt to help keep it closed and raise boost. I know exhaust backpressure would cause the condition you stated. My exhaust begins with 8" of 3" diamater pipe with about the same length of 3. 5" before changing to 4" with a straight through Walker off-road big truck muffler.































'