Hey SL,

I'm having some incredibly frustrating problems trying to raise my boost... Obviously there's a lot of important variables here so I'll try to be brief.

I'm running the old turbonetics kit (t3/t4 turbo, log manifold, evolution external WG - with a 9 lb spring + 3 shims). I'm making 12 lbs of boost but I'm trying to raise it to 22 (what the car was originally tuned for). I suspected the problem was the world racing boost controller but it wasn't (although it isn't operating the way it should...). As a temporary setup, I plumbed a vacuum line off the intake manifold into a manual ball and spring type boost controller set at 16 psi.

I still can't build past 12 lbs, however it seems to build boost right up to redline. The only other force at work here is exhaust back pressure right? So that must be cracking open the wastegate... But how in the crap could there be that much back pressure? What should I look for? Isn't back pressure bad for performance? Obviously a larger spring would work but IMO it's not worth it if I'm sacrificing performance because of back pressure.

Help please

 

Can you here the blow off valve opening when you hit 12psi? On my Honda it was making too much boost and the bov was opening up past a certain psi. It could be that or the waste gate opening at 12 psi. or maybe the turbo is leaking by?

 

are you still runing the raptor bov

 

Generally double the wastegate spring pressure is about all your going to get, atleast that's been my experience with all the mbc's and electronic boost controllers iv played with. You can get it to spike higher than double but it won't hold. Sounds to me it would be best for you to try a larger spring (stiffer spring).

Back pressure produced on the stock axle back iv noticed will reduce total pressure by one to two psi on an 8 psi spring in a tial 38mm wastegate.

The bov if adjustable should be adjusted for the higher boost otherwise it can leak pretty badly. To find out a simple boost leak test will tell the tale of what is and is not sealing.

Good luck and happy boosting

 

DO you have the boost controller setup right? You should have connections to top and bottom of the wastegate. No matter how much exhaust pressure, you should still get an increase because you are putting pressure on the opp side of the diagphragm.

 

Thanks guys I appreciate the responses.

I am still running the raptor bov, but don't hear it opening. I'll definitely check the pressure it opens at. This sounds a lot more plausible than back pressure considering I'm running a catless 2.5" mandrel bent turbo back exhaust...

As for the electronic boost controller - it was definitely set up correctly, but seems to have stopped working correctly. When the solenoid is de-energized it should be flowing from the vacuum source to the top of the WG right? It wasn't flowing at all. While energized the intake and exhaust ports are connected though.

 

Figured it out.

Turns out the manifold pressure line was connected to the wrong port of the bov. An easy fix is a good fix

I still could use some clarification on the boost solenoid though.

 

i was going to say i have a turbonetics evolution wastgate with 9 psi spring and i hold 22 psi all the way up to 7400 rpm lol

do they sell stiffer spring like 16+? is so please post link all i have found is those shims to increase with out boost controller.

 

What controller are you using? Greddy profec b won't hold over double, iv tried... Lol
Wish I was able to play with all the electronic controllers out there.

 

I have the world racing TBC-1. When I power it, the in and out ports are connected. When it's powered down, nothing is connected. You would think that it would run constantly powered but it doesn't.

Aryana, turbonetics doesn't make any other springs for whatever reason. From what I understand most other springs are designed similar to the ones used in tial WGs, and those don't work. Definitely leaves us in a pretty crummy spot....

 

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