Think I need to port the wastegate hole??

Flyin Brian

Flyin Brian

Member
Joined
Jun 18, 2011
I did some searching on here and I think I know the answer but wanted opinions. I got my turbo upgraded from a 58 mm compressor to a 62 mm compressor. Garret .63 exhaust housing, .60 compressor housing, 65 mm turbine, GN1 3-1/2" downpipe with 46 mm external wastegate. With the old turbo and old cracked ATR headers and both the large 13 psi blue spring and small blue 7 psi springs in the wastegate the boost would max out around 25 psi. I took the large 13 psi spring out when I put the new turbo on and left only the small 7 psi spring in there thinking that would be safe. Also installed the TA headers. Did a run and the boost went up to nearly 28 psi. So, I ran the wastegate with no spring and took the hose off the top port so the gate is open all the time. Ran it again and the boost still went up to nearly 26 psi, slow spool-up. Wastegate hole is already at .950 inches now. Pipe to external gate is close to 1.125 ID. Do I need to port the hole further to get the boost down and controllable? I ask this as at 25 psi boost I am already out of injector now and running lean. Would like to run around 23 psi for now until I can get bigger injectors. Shift RPM also went up from around 5800 to 6300 but my converter is way wrong for this combo. New turbo seems to be moving a ton of air! Rest of build in my sig. Thanks.
 
You will need to open that hole up quite a bit to control the boost conventionally with both ports and a spring. Youre driving into the converter much harder thats why the shift rpm is higher.
 
I've seen the gn1 external gate not have the hole cut out all the way where the Wastegate plumbs back into the pipe. This would also cause an overboosting condition.


Posted from the TurboBuick.Com mobile app
 
The GN1 downpipes have a pretty small hole for the wastgate, way smaller than the pipe, that will need to be opened as well or you will never control the boost.

Bryan
 
Thanks Brian. That's what I was thinking. Want to get it where it is controllable. Will probably open it up to 1.05 and test first. Would be nice if I could get it to where it works with one of my existing wastegate springs so I don't have to buy another one. Going to buy the right converter in a couple of months. Turbo rocks by the way!
 
Thanks guys, I did notice the weld in the GN1 wastegate pipe at the turbo flange seems excessive. I plan on cleaning up these areas as much as possible without compromising weld integrity. Going to do it in steps so I don't go too far.
 
Ok, I ported the wastegate hole in the exhaust turbine housing out to 1.05" and radiused it back on the inside good. I also ported the hole in the downpipe flange out to 1.25 and did a ton of other porting and cleaning up on the wastegate pipes at the flanges. Did another run with no wastegate spring and the top port open and the minimum boost is still 26 psi. Should I open up the turbine hole to 1.15" now? Also how do I check the hole where the wastegate pipe joins back into the downpipe? It is impossible to see by looking down the pipe.
 
Yes, I have the Turbonetics manual boost controller. But I have the top port on the gate unhooked and the bottom port hooked up so all the boost signal is going to hold the gate open. Is my thinking right here?
 
Do you have the black controller or the billet controller? If you have the billet I would take it off IMMEDIATELY !!! They suck BALLS !!
Install the 7lb spring and connect the turbo to the bottom port on the wastegate. Take a spin to test...should get 6-8 psi.


Bryan
 
After testing...connect the turbo to the inlet of the controller and the outlet to the wastegate, unscrew the controller so that you are at the minimum and start slowly increasing the controller to your desired boost

Bryan
 
You can also T into the line between the turbo and controller to put pressure on the top port of the wastegate...this will give better results with control

Bryan
 
I have the black controller. If I have no spring in the wastegate and the bottom port of the wastegate hooked directly to the turbo now and get 26 psi boost, how is boost going to be lower if I put the 7 lb spring back in the wastegate? Am I missing something here?
 
Remove the controller, install spring, connect the turbo straight to the lower port to check first

Bryan
 
Also make sure you have the correct ports on the controller, they are backwards out of the box...inlet on the left outlet on the right

Bryan
 
You would need a boroscope to see the wastegate return opening in the dp. Either that or cut it off clean it up and have jt welded back on.


Posted from the TurboBuick.Com mobile app
 
When I had the wastegate off the downpipe last time I checked the opening and closing of it. With no spring in it you can open it all the way and close it all the way just by blowing in the bottom and top ports respectively. Is this enough to verify function? I can go ahead and put the spring back in it and do the test as well. How are the ports on the controller backwards out of the box?? The only markings I can find on the controller is the arrow stamped on one of the ports and the arrow points outward on the port away from the body. I assumed this is the outlet?? Originally I had the port on the controller with the arrow pointing out going to the top port on the wastegate. I had a tee in the line between the pressure tap on the compressor scroll and the bottom port on the wastegate. Tee was connected to what I am assuming is the inlet on the controller. I had the controller turned full counterclockwise for minimum boost. Was this correct??? Thanks for all the input. I will have to see if I can borrow a borescope from work to check the wastegate pipe to down pipe connection. I don't want to cut it up if I don't have to as I just got the downpipe and headers coated last month.
 
If it is moving freely , install the 7lb spring( this is what I use as well.)
Output from turbo to input on controller, From output of controller to bottom port on gate.

Bryan
 
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