Wastegate opening early

[90AWDTalon]

I recently installed a turbosmart ultragate 38 on my car. It came with a 7psi outer spring installed, I swapped this for a 10psi outer spring and a 7 psi inner spring, for a total of 17psi. I'm running no boost controller while I get everything working, just straight off my intake manifold to the bottom port at the wastegate, the top port is open to atmesphere per the instructions. With my external dump it is real easy to hear when the wastegate opens. It sounds like it is cracking open at 10psi and fully open at 14psi. I'm also creeping to 20psi. Spool feels slow, but I assume this is the wastegate opening early.

This observation is totally by sound. So I'm unsure when the wastegate is fully open, but it definiately is starting to open at 10psi. Is it normal for an external wastegate to start opening so much earlier than its spring rate? Is there any way I could rig up some kind of valve to use as a gain control at the top port? Same idea as shimming or adjusting internal style wastegate arms to stay closed longer. I know when I reinstall my mbc it'll help some, but will it be enough?

I plan on running 28psi or so. With the springs that came with the wastegate I can set the base pressure to 7psi, 10psi, 14psi, and 17psi. Am I using the best spring combo for this or would a lighter spring and turning up the mbc more work better?

 

[jpbrazill]

I would plumb it differently. I ran into the same problem as well. Instead of the MBC location being in-between the mani and the wastegate, run the mbc off of post- intercooler piping, and then to the lower nipple on the gate. This should solve the issue.

Remember that the pressure in the mani is different than the piping. Also, its a good idea that your boost source is pre-throttle plate. Good luck!

J.P.

 

[90AWDTalon]

Is it possible that the turbo could be spooling faster than the boost gauge can respond? It definately sounds like its opening early in low gears, but at high gears when the turbo spools slower it doesn't sound like it opens early. The slow spool I was getting was a bad gasket at the manifold to wastegate, it is spooling very fast now. In lower gears even though it sounds like the wastegate is open it continues to build boost. Both the wastegate and boost gauge are tapped at the intake manifold, my boost gauge is an autometer phantom 45psi boost/vacuum gauge.

 

[playitlouddsm]

I believe that i have your same problem. I'm running the tial 38mm external wg, dumped. I have my boost set at 15 psi, but it sounds like my wg is opening way too early and making the car fall on its face. It will pull until the wg opens then pull just stops.

 

[jpbrazill]

Is it possible that the turbo could be spooling faster than the boost gauge can respond? It definately sounds like its opening early in low gears, but at high gears when the turbo spools slower it doesn't sound like it opens early. The slow spool I was getting was a bad gasket at the manifold to wastegate, it is spooling very fast now. In lower gears even though it sounds like the wastegate is open it continues to build boost. Both the wastegate and boost gauge are tapped at the intake manifold, my boost gauge is an autometer phantom 45psi boost/vacuum gauge.

I seriously dought that your gauge is not fuctioning correctly. Your gauge wont follow the boost response, it shows exactly what it is instantly. Did you change the plumbing for your boost lines yet? I would try that before any thing.

What springs do you have in the gate? How many pounds of boost are you wanting to run?

J.P.

 

[90AWDTalon]

I believe that i have your same problem. I'm running the tial 38mm external wg, dumped. I have my boost set at 15 psi, but it sounds like my wg is opening way too early and making the car fall on its face. It will pull until the wg opens then pull just stops.

Mine keeps pulling after it sounds like it opens. I don't believe that mine is opening early. Just for some reason I'm hearing the wastegate before my boost gauge is registering full boost. I'll keep track of my rpm's instead of boost to see what my rpm is when it sounds like it opens. In the lower gears things just happen too fast keep an eye on the road, rpm's, and boost gauge all at the same time. 4 and 5 gear look, feel, and sound normal.

 

[90AWDTalon]

I seriously dought that your gauge is not fuctioning correctly. Your gauge wont follow the boost response, it shows exactly what it is instantly. Did you change the plumbing for your boost lines yet? I would try that before any thing.

What springs do you have in the gate? How many pounds of boost are you wanting to run?

J.P.

I reattached my mbc, currently have boost set at 26psi, and slowly increasing boost while keeping an eye on knock. I have the 10psi outer spring and the 7 psi inner spring installed in the wastegate.