Da bung hole...

[Chuck Leeper]

Just unpacked the new PTE 5831E. Checked the w/g puck vs the exh hsg port.
Here's a pic. The puck doesn't come even close to centered. {or, the hole is way off}. Had that problem, before!
The puck is 1.5", the hole is <1".
As you can see, there's very little "overlap" at one side.
Would I be GTG, to port the hole out on the "fat side" to within 1/8+, and stay off of the skinny side?
As it is now, it looks to me to be a recipe for boost control issues.
I could do a bit of hole elongation on the dp flange, and get a bit better overlap at the skinny side.....

Opinions??

 

[turbo nasty]

That's the normal stagger. Dont go that thin at first as you may not need that much for control. Also contour the turbine entrance slightly over towards the hole.

 

[fastblackracing]

My 71 was off more than that. We had to make up a stainless ring and press it on the flappper/puck and weld it up, I think we ended up at 1 5/8" puck size when all was said and done. Ported the hole to just under 1", But I am not concerned about low boost......If that has what appears to be 1/8" overlap to the hole I think you are good to go ...What boost do you intend to run will dictate how big to open it. If your too big its a pita to run hi boost.

 

[dynoman]

I had the same problem with wastegate puck misalignment , only mine was not even completely covering the hole . I still got 19 psi out of it but that was all , and I needed 25-28 psi . First I got a plate from Bison to relocate the hole and I had it machined to 1.19" for a 1.5" puck . After that I could not get boost over 24 psi , so I ordered a new plate machined it to .95" per Bison's suggestion . Now boost is set at 28 psi with some room left on the boost controller . I would leave it as is , if boost runs away port the hole .

 

[Chuck Leeper]

As "small" as this turbo is, I'll just leave it for now. Totally a streeter
It's equipped w/ Alky Control, totally stock long block, injs, dp, PTC converter, and a stock i/c. I'm guessing it's tongue will be hangin out at 22-maybe 24 psi
Turbo is "supposed to" move enough air for 580 at the fly. We'll see.

Thanks for the help!

 

[aminga]

 

[bison]

I had the same problem with wastegate puck misalignment , only mine was not even completely covering the hole . I still got 19 psi out of it but that was all , and I needed 25-28 psi . First I got a plate from Bison to relocate the hole and I had it machined to 1.19" for a 1.5" puck . After that I could not get boost over 24 psi , so I ordered a new plate machined it to .95" per Bison's suggestion . Now boost is set at 28 psi with some room left on the boost controller . I would leave it as is , if boost runs away port the hole .View attachment 261891 View attachment 261892 View attachment 261893

Nice work. Most look at the wastegate as a regulator of manifold pressure. If you look at it as a regulator of exhaust pressure it's easier to understand the relationship to its effect on manifold pressure. Doubling the surface area doubles the exhaust pressures mechanical advantage to help overcome the wastegate spring. Going from 1.2" to .950" is a 36.3% reduction in cross section. The cracking pressure can be calculated based off this info. There's other things that come into play as it opens but the big problem is usually overshoot or low boost. The cross section is very important when trying to get the correct operational range


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[Chuck Leeper]

I left it alone. The hole measured right at 15/16"....real close to .95".....938. GTG.

 

[fastblackracing]

Nice work. Most look at the wastegate as a regulator of manifold pressure. If you look at it as a regulator of exhaust pressure it's easier to understand the relationship to its effect on manifold pressure. Doubling the surface area doubles the exhaust pressures mechanical advantage to help overcome the wastegate spring. Going from 1.2" to .950" is a 36.3% reduction in cross section. The cracking pressure can be calculated based off this info. There's other things that come into play as it opens but the big problem is usually overshoot or low boost. The cross section is very important when trying to get the correct operational range .
It does make a big difference when I opened mine up from .940 to .990ish, just under 1 inch, the boost came down 5 pounds with no other changes. best to take baby steps if you going to use the turbo to make some power.