Turbo makes boost with wategate open?

[DBB mini]

Finally got my hybrid conversion running and driving. I can't control the boost. I even removed the wastegate actuator arm to let the puck float and at 4500 it starts at 15psi and climbing. With the actator connected it spiked to 30psi before blowing off an ic hose. I ran the same turbo in 2006 on an 8v setup and no problems. Its a Garrett gt2871r turbo with a gt3071 compressor wheel and housing, hot side is a ATP.63ar t3 inlet with a 3"id ATP ultimate internal wastegate and 3" mandrel downpipe. 100% stainless header I made and full3" exhaust straight thru muffler. My theory is that there is not enough backpressure in the turbine housing to allow the exhaust to bypass the turbine. Any thoughts? Ideas? I am going to try to machine the wastegate exit on the scroll at more of an angle, try to almost guide the exhaust a little towards the wastegate. Right now its just a hole drilled in the scroll at 90 degrees with exhaust flow, unless the scroll is under pressure, it can't escape out the wastegate. Did I make any sense?

Coy

[DBB mini]

A pic of the header.

Header (Before I relocated the flange) and the ATP ultimate internal wastegate. I did not run this on the 8v setup.

[cordes]

You may want to open up the WG hole a little bit. What is the timing like? I doubt that is your problem, but if you really pull timing it will spool the turbo like nobodies business.

When you say the WG was all the way open, you mean the puck was flapping around in the breeze?

[DBB mini]

You may want to open up the WG hole a little bit. What is the timing like? I doubt that is your problem, but if you really pull timing it will spool the turbo like nobodies business.

When you say the WG was all the way open, you mean the puck was flapping around in the breeze?

Yes flappin in the breeze, 15psi boost and climbing fast. Timing is set at 10, G head cal I've been playin with but I've done nothing to the timing.

[turbovanman²]

Do you have any preload on the puck?

[contraption22]

That's a pretty tiny turbine for a hybrid, isn't it?

[DBB mini]

Do you have any preload on the puck?

Nope. It was flapping, then I hooked the actuator arm back up (preload) and it went to 30psi

[DBB mini]

That's a pretty tiny turbine for a hybrid, isn't it?

Capable of over 480hp with the T3 housing, good enough for me. Plus it spools insane. Garrett advertises it for a 1.8 to 3L engine making 300-475hp with the tiny T25 inlet.

[turbovanman²]

Nope. It was flapping, then I hooked the actuator arm back up (preload) and it went to 30psi

Interesting, maybe the wastegate hole needs porting. What happens if you just run manifold vacuum to the can?

[bakes]

The waste gate hole is to small for the amount of exhaust needed to be dumped
I was making 20# with the puck removed since then ported the waste gate hole and reinstalled the puck boost is now stable.

[DBB mini]

Interesting, maybe the wastegate hole needs porting. What happens if you just run manifold vacuum to the can?

Boost will go higher with manifold vacuum, holds the can tighter.

[DBB mini]

The waste gate hole is to small for the amount of exhaust needed to be dumped
I was making 20# with the puck removed since then ported the waste gate hole and reinstalled the puck boost is now stable.

Do you have any pics?

[roachjuice]

i am a witness to this mystery boost lol.

[Mopar318]

With the wastegate unhooked and the valve flapping...couldnt the back pressure in the exhaust still hold the valve closed? It seems like a better test would be to pull it open and wire it upen. So it cant close up on you.

[DBB mini]

With the wastegate unhooked and the valve flapping...couldnt the back pressure in the exhaust still hold the valve closed? It seems like a better test would be to pull it open and wire it upen. So it cant close up on you.

If this is true then when the wastegate is open it will spool the turbo even harder because it would be drawing thru the wastegate and the header. Not likely. Besides I probably have near to zero backpressure from the turbine wheel back.

[DBB mini]

One more thought... I machined a chamfer on the turbine at the exit of the turbine wheel. This opened it up a bit right as the exhaust exits the exducer of the turbine. I'm wondering if it reduced turbine pressure that much? Surely not.

I removed the turbo today thinkin about takin it to the shop tomorrow for some port work on the wastegate. I took a couple pics.

Here you can see the chamfer.


A side shot of the wastegate/assy

[cordes]

There is a ton of meat there that you can remove, and that should help the problem.

[DBB mini]

Well I ported a ton on the wastegate hole and it WORKED!!!
It now holds 10psi of boost on my lowest setting with the can hooked up woot!!
Now its time to tune and then post a video of a big smokey burnout Thanks for all the help.

I ported until a one inch dia pin went thru.

[gasketmaster]

Looks nice

[turbovanman²]

I would port the outlet hole too, looks like it could be ALOT bigger.