22psi springs in Tial External Wastegate...can only build 18 psi

[4gfun]

There are no boost leaks and I have temporarily bypassed the BOV just as a quick test. I put 22 psi worth of springs in and didn't use an MBC to see what would happen.

I could only get to 18 psi. If I use an MBC I can get to 22 psi very easily...heck I can get 30 psi with the MBC only half way in...but it always falls down on me.

What does it mean if I have gone through all of this and connect the External Wastegate to a boost source only to have it reach 18 psi when the springs are 22 psi? I have BLT to 30 psi.

I have had this problem for months (boost falls from 22 psi to 17 psi by only 4500 rpm with a Big 16g) and all I can think of is the turbo being bad at this point.

Thanks

 

[jrohner]

Check for leaks on the exhaust side. Also, it's not uncommon to boost lower than the wastegate spring, as there is exhaust backpressure pushing on the wastegate as well.

Running some pressure to the top port on the wastegate helps push the wastegate closed, and helps for holding boost up top.

 

[TurboAnything]

It tends to be hit or miss with spring changes. I am running a 17psi spring and cant get lower then 24psi.

 

[4gfun]

You have a pm. Someone suggested adding some pressure on the top port as a quick test...can you just tee to both ports using an MBC?

The reason that I took the angle of swapping springs is that the top port was missing. I could just buy the fitting for the top without having to remove the wastegate (major pain on a GVR-4) (Have to drain the radiator each time)

Thanks!

Check for leaks on the exhaust side. Also, it's not uncommon to boost lower than the wastegate spring, as there is exhaust backpressure pushing on the wastegate as well.

Running some pressure to the top port on the wastegate helps push the wastegate closed, and helps for holding boost up top.

Wow, I had no idea. My real problem is the boost fade after I use the MBC to get it to 22 psi.

It tends to be hit or miss with spring changes. I am running a 17psi spring and cant get lower then 24psi.