It's not really about the actually wastegate diameter size, it's about directing the exhaust into to promote the flow.

Right now the path of least resistance is still just going through turbine.





Think about a highway, would you rather have to stop and turn 90° or take a nice offramp?

 

Also think about how you would force air to open the flapper. You want it to slip downward so it hits the wall of the wastegate and forces it open

Here is a shitty pic on a different turbo but as you can see the air in the before pic doesn't even want to go into the wastegate. So by dipping a valley and making the air ram into that wall it is able to create enough pressure to open the flap.

 

On my setup, a 2560r with the wastegate tied open, 4.8 psi at 7k is reasonable?

 

I swear I think you just post the opposite of everything. I know, I know, probably just another mis-post, but I feel I must correct you:
You DON'T want the exhaust pushing the flapper open. You never want the flapper blown open. It happens on other cars, and it sucks, because then you will have the opposite of boost creep, which also sucks.

It's about flow, not pressure. You want it to flow well to the port and through the port. OPening/closing is done by actuator only unless your actuator sucks

 

Yes. Frankly, anything below the target boost by enough margin to allow no creep under any circumstances should be sufficient. Account for the fact that cold weather conditions produce much denser air and more chance for creep.

 

Thanks.

I didnt create much of a channel for mine. I mainly worked on knocking down the inner radius leading into the port. Not sure if it will be the same on a churbo?

 

correct. the wastegate actuator pushes the wastegate flapper open once the boost pressure on the diphram overcomes the preload.

if you port the diameter of the wastegate hole, you could possibly run into this very situation where you can never raise boost with your current wastgate actuator, because the forces on the flapper is greater than the preload on the spring and it stays open when you want it closed to build more boost.

 

How the hell could the exhaust push the flapper open with preload on the WGA? No **** its about flow. I guess im just being misunderstood.

 

Ahh I see what I did "force air to open the flapper" I meant "force air through the open flapper". Assuming the flapper is open, the channel provides a smother bleed of boost to all more pressure to escape.

 

I don't think you realize how much pressure is in the hotside at high boost/high flow situations. There are numerous examples out there of flappers being blown open by exhaust pressure and the wga pre-load can't hold it, so the car drops boost.

*edit:
ok so we're cool then. lol

 

danger to the butt plug.

 

LOL I still cant even write a damn sentence correct even when I edit myself. I guess its the price I pay for sneaking on MT at work

 

I vehemently disagree with the majority of you here.

Port diameter is about ten times as important as blending on this turbo, no material or room to "blend" anything. You'll never ever blow the wastegate on this turbo open, it's not happening. You should be able to make much less than 6 pounds at redline. A 1.6 can't be that different, I make less than 2 psi with the gate wired open. A 1.6 can't flow that much less than 1.8, nope.

Also, new same turbo that looks different.

REV9 T3 Turbo turbocharger Compressor AR42 Turbine 48 Internal Wastegate 350HP | eBay

 

Im gonna disagree with you. Pressure trying to go around a 90 degree corner is always harder than pressure going around a 45 degree one and who drives a 1.6 anymore? I though we all just used them as garage art or made coffee tables out of them

 

I read the early pages about size, pressure and flow. I focused on smoothing and radiusing and didn't increase the diameter but I wussed out on the channel since Lars blew that hole in his housing, going a little too far.
What about the back side? I guess we don't want to make it easy for air to slip back out. I left mine alone except for smoothing out a few nicks I made by mistake.
There is still room for more on mine without increasing the diameter.

 

Lars went way to far on the port. Just go slow and use a micrometer to measure thickness as you go. Right at the edge of the whole you should have a little over the thickness of a nickle then taper upwards and blend the walls.

 

this was my port:







this was my last dyno I ever did (im trying to find my logs to show the wastegate):

 

Was this on a 1.6?

 

yes.