2G Major overboost issue

[Ramsey91]

Alright so I’m having major over boost issues and I’m kind of stumped right now. I’ve tried two 38mm wastegates and a 44mm thinking maybe 38mm was too small, but same issue. I thought wastegate may be stuck but considering I’ve gone through three new ones it’s doubtful. Gonna bench test them though to see what they are opening at.

I’m running a gtx3071 on SD and bypassed ebc by going straight from the compressor housing to the bottom port and top port vented. Also checked for leaks but I haven’t found any. I’m gonna boost leak test it again and spray everything with soapy water to see if there’s any small leaks.

What else should I be looking for? I know positioning and flow is important as well so maybe this is the issue? I can post pics/video of setup if needed.

I’m having the car remote tuned by Ricky at rixracing and he’s been helping me but I feel bad constantly asking him questions considering how busy he is. I’ve also been doing research but wanted to ask to get some more input.

I should also mention I’m just trying to see base pressure so I can start tuning. I’ve used a 9psi spring combo, 14psi combo on 38mm and 11psi spring combo on the 44mm. I saw almost double base on first attempt and let off immediately. The other attempts have been acting the same but I've been letting off as soon as it goes over. Boost starts building at 4krpms and starts to really let go closer to 5k.

 

[Ramsey91]

Yeah just wanted to make sure if the hole is completely drilled and passed through until inside the compressor housing.

I just looked and it does go completely through the housing

 

[Ramsey91]

FWIW I battled this about a year ago. My issue ended up being the gate not opening enough.

I was over shooting target boost by a lot.

I took my springs out to verify if it was a my holes aren’t big enough problem. To my amazement I could barely build boost.

I ended up removing the gate and using the tee from the BLT tester I made. Air compressors have built in regulators fyi. Then I could see exactly where it would crack open and how far it would open.

For some reason my 19psi spring would not let the gate fully open. Ended up using a 15 psi spring and ended up fixing the issue. I use an EBC now so I can hit my higher target.

I encourage you to bench test it.

-Daniel

Definitely gonna bench test them. Just gotta get some fittings to rig something up. Just seems weird that all three wastegates would have that problem.

 

[pauleyman]

Honestly not trying to poke you. Can you show us the compressor fitting location?

 

[Ramsey91]

Honestly not trying to poke you. Can you show us the compressor fitting location?

It’s where that screw is on top

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[pauleyman]

I will vote that's your problem. Try a line to the intake manifold just to see. Yes that's in the housing but it doesn't appear to be at the outlet.

 

[Ramsey91]

Update, I bench tested the 38mm with 9psi and 5.6psi spring (14.6psi total) and it’s started opening at 25psi and fully opened at 28-29 so pretty much double the spring rate.

Tested 44mm as well with 5.5psi and 6.1psi (11.6psi total) and it’s seemed to open at the around 10-11 and fully open closer 18-19. Hard to tell cause my gauge starts at 20 but that’s the general area.

 

[Ramsey91]

I will vote that's your problem. Try a line to the intake manifold just to see. Yes that's in the housing but it doesn't appear to be at the outlet.

Sorry I’m still pretty new and learning but could I T into the bov to manifold line? And would I run the line from wastegate?

 

[DSMPT]

It’s where that screw is on top

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So you mean this tapped hole with a plug? If so, that's exactly what I was saying that you are using a wrong hole. That's for a speed sensor and not to connect to where builds the boost pressure.
Change the location for the fitting like Paul said. Then your over boost problem would probably be solved.

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[Ramsey91]

So you mean this tapped hole with a plug? If so, that's exactly what I was saying that you are using a wrong hole. That's for a speed sensor and not to connect to where builds the boost pressure.
Change the location for the fitting like Paul said. Then your over boost problem would probably be solved.

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god i feel stupid... it looked like it was tapped for boost

 

[DSMPT]

god i feel stupid... it looked like it was tapped for boost

No worries, it happens to everyone. But you still need to make sure if it was the cause of the over boost. Change the location to take a boost source for wastegate and see if it would work as it should.

 

[Ramsey91]

No worries, it happens to everyone. But you still need to make sure if it was the cause of the over boost. Change the location to take a boost source for wastegate and see if it would work as it should.

Yes most definitely will. I plan on doing a t from the bov so hopefully it’ll work out.

 

[DSMPT]

Yes most definitely will. I plan on doing a t from the bov so hopefully it’ll work out.

Just let us know the result. You can drill and tap in red circle on the compressor housing if you like.

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[Ramsey91]

Just let us know the result. You can drill and tap in red circle on the compressor housing if you like.

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Well that was the answer to my problems. I’m only seeing around 12-13psi now at WOT. It’s a 9.9psi combo total though so is it normal for it to be at 12-13psi? I did forget to replace the fitting with a screw on the compressor housing, so gonna try again after it cools off and I replace that.

And I’ll probably tap the fitting once I move and just tap of bov for now since I don’t trust myself yet to tap it and I got no one around me that I trust to do it sadly.

 

[Vegas Smith]

Well that was the answer to my problems. I’m only seeing around 12-13psi now at WOT. It’s a 9.9psi combo total though so is it normal for it to be at 12-13psi? I did forget to replace the fitting with a screw on the compressor housing, so gonna try again after it cools off and I replace that.

And I’ll probably tap the fitting once I move and just tap of bov for now since I don’t trust myself yet to tap it and I got no one around me that I trust to do it sadly.

Yeah some cars effectively have a minimum boost they'll hit regardless of spring. Mine is like 16 psi.

 

[DSMPT]

Well that was the answer to my problems.

Yeah for sure. The wastegate was not seeing boost. And this is why we suspected the boost pressure may be fed to the coolant port first. It causes the same.

I’m only seeing around 12-13psi now at WOT. It’s a 9.9psi combo total though so is it normal for it to be at 12-13psi? I did forget to replace the fitting with a screw on the compressor housing, so gonna try again after it cools off and I replace that.

With which wastegate? 38mm or 44mm? I don't know how much boost pressure you would finally want, but just keep in mind that to hold low boost pressure, you better have a larger wastegate. So if you now have 12-13 psi with a 38mm wastegate/10 psi spring, a 44mm gate may give you a steady 10 psi with 10 psi spring combo. If you would go with higher boost, probably both 38mm/44mm would work just fine. Also like Vegas mentioned that the min boost would depend on the setup too.

 

[Ramsey91]

With which wastegate? 38mm or 44mm? I don't know how much boost pressure you would finally want, but just keep in mind that to hold low boost pressure, you better have a larger wastegate. So if you now have 12-13 psi with a 38mm wastegate/10 psi spring, a 44mm gate may give you a steady 10 psi with 10 psi spring combo. If you would go with higher boost, probably both 38mm/44mm would work just fine. Also like Vegas mentioned that the min boost would depend on the setup too.

the 38mm and that would make sense why its going slightly higher. I plan to go higher in boost, just not sure how high I can go on completely stock engine, but I would imagine the 38mm will be fine. For now I'm just trying to get my base set so we can tune from there.