RJC boost controller and adjustable WG rod = boost creep?

[cuda6pak]

Hey guys, I got around to doing a boost leak test on my car and fixed a few hoses that were cracked and leaking. Prior to this the car would make 16psi and stay there exactly.

Once I fixed the leaks it was making 17+psi so I wanted to back the boost down a tad. The RJC was already almost all the way loosened so we cut a coil off the spring and adjusted the wastegate rod/RJC combo. We eventually got it running pretty good it just seems to be creeping a lot, especially in high rpm in D.

I read some of the boost control and boost leak threads and saw that RJC recommends that you have 1/8" of play in the WG rod.....well, if I do that the turbo spools SLOOOOOOW. I have to pretty much make the rod as short as possible to get back on there, which spools FAST but it tends to creep up top. Any recommendations?

EDIT: Car is an 87 GN with a TE44, THDP with hooker exhaust, mease big neck, ported heads, built motor, Art Carr Tranny and 3000 NL stall, Translator and LT1 MAF etc

 

[RUQWKNF]

Hmmm,
That's a tough one. Here's a thought, have you thought about porting your WG hole in the turbine housing? This typically helps with boost creep issues. And here's why. You said you have ported heads on a built motor. This would equate to more exhaust making it's way to your turbo. Typically on turbos sized from 61mm and up, it's always recommended to port the wastegate hole out to just smaller than the puck size on your downpipe. This might be causing your creep issues you are seeing.
One other thought. If you have a heavy duty actuator and are trying to adjust it to below 17#s, it ain't gonna happen. HD actuators are rated from 18psi to 30.
Just a couple of thoughts.

Patrick

 

[cuda6pak]

I remember reading on here that porting out the wastegate hole was actually a bandaid? What's the root cause of it? I don't think it's a heavy duty actuator, because I can get it to hit 10-12psi pretty quick and then it slowly creeps from there.

I just can't get this damn thing back to where it used to be Thought I finally got it right the other night...1st and 2nd it was pretty solid, then in 3rd the farther up in the RPM's I got the more it started to creep, eventually knocking pretty bad.

 

[bison]

I remember reading on here that porting out the wastegate hole was actually a bandaid? What's the root cause of it? I don't think it's a heavy duty actuator, because I can get it to hit 10-12psi pretty quick and then it slowly creeps from there.

I just can't get this damn thing back to where it used to be Thought I finally got it right the other night...1st and 2nd it was pretty solid, then in 3rd the farther up in the RPM's I got the more it started to creep, eventually knocking pretty bad.

The root cause is that the exhaust volume is too much for the turbine housing a/r and wastegate hole to control boost when the gate is fully open. Porting the hole is not a band-aid. It is necessary if you have a free flowing exhaust and are running above the stock settings. Your symptoms are clearly pointing at the wastegate hole. Boost creep at higher rpm in 3rd equals wastegate hole too small. Open it up and the problem should disappear. If you set the wastegate rod to loose then exhaust pressure may force open the wastegate under boost. Start with a little tension after you open up the hole. A couple turns past zero tension is a good start. The tighter you go beyond a certain point will limit the amount it can open under boost and could cause a boost creep issue itself. You wont get to this point with the high pressure diaphragm till you try and shorten the rod a lot. You will be well into the 25+ psi range for this to occur without the RJC controller. With it you could go even further.

 

[vacuum 6]

If I'm not mistaken RJC recommends to have tension on the rod.

 

[breiter]

RJC Boost Controller

I run the RJC boost controller with a TE67. Limit Engineering built the turbo and new I was running a THDP. The WG hole was sized accordingly. I followed the instructions RJC (Jason) provided and set my HD rod as explained. I have run boost any where from 16lbs to 23lbs simply by adjusting the RJC controller and have not had any problems. If I am cruising in OD at 60mph or so and slowly accelerate I can make boost creep happen but it is understandable. Set the rod as instructed and look for other possible vacuum leaks. I also by-passed the factory waste gate solenoid. It is still electrically plugged in but the vacuum port on the turbo runs to the controller, which runs the vacuum line that was plugged in to the factory WG solenoid.

 

[cuda6pak]

The root cause is that the exhaust volume is too much for the turbine housing a/r and wastegate hole to control boost when the gate is fully open. Porting the hole is not a band-aid. It is necessary if you have a free flowing exhaust and are running above the stock settings. Your symptoms are clearly pointing at the wastegate hole. Boost creep at higher rpm in 3rd equals wastegate hole too small. Open it up and the problem should disappear. If you set the wastegate rod to loose then exhaust pressure may force open the wastegate under boost. Start with a little tension after you open up the hole. A couple turns past zero tension is a good start. The tighter you go beyond a certain point will limit the amount it can open under boost and could cause a boost creep issue itself. You wont get to this point with the high pressure diaphragm till you try and shorten the rod a lot. You will be well into the 25+ psi range for this to occur without the RJC controller. With it you could go even further.

Referencing this post

http://www.turbobuick.com/forums/tu...html?highlight=port+wastegate+hole#post706475

I shouldn't have to port anything since I'm running a PTE44, right? I guess only popping the downpipe off and checking can tell though.