Looking for compressor surge solution

[TeeLew]

Also if you have stiffer spring in your blow off valve to only open past 15psi....that's not right. That means if you lift the throttle when you're making under 1- 15psi you're going to not vent the air which is bad

you have equal boost on the other side of the bov which keeps it closed under boost.

the spring is there to keep the valve open under idle vacuum, no stiffer.

this is turbo 101, where did you kids go to school?

You're kinda coming off as a douche, so bring it down a notch, huh?

It's a compromise. If you have it venting any time you lift the throttle (as they come from TurboSmart), then you don't have to worry about compressor bearings, but the on/off throttle lag is hurt and you have to listen to the damned thing vent all the time, even with essentially no boost (it's the pressure difference between the intake and reference, so even if the manifold has a slight vacuum, it may still vent), because the BOV pressure difference is enough to release it. We have to have the BOV or BPV, or we'll start hurting compressor bearings. You tune the BOV to give you the middle ground you chose. It will always be a compromise. This is why I prefer the BPV, it's less of a compromise.

I know how I drive. I'm either on it, it which case, it vents or driving like grandma, so it doesn't matter. In the in-between times when I could potentially be hurting the turbo, I'm willing to accept. It's never happening at high boost levels. I don't know the number perfectly, but full vent is about 13-15 psi and it starts to tickle the valve at maybe 8 psi of boost. I could probably bring it down a few psi, but in overall abuse to the turbo, I doubt it would make much of a difference.

I'm not telling you to do it. I'm just saying that's how I have done mine. If you don't want do it that way, then, by all means, do what works best for you.

Sponsored

 

[robvas]

You don't have to listen to thing vent all the time. It's not a centrifugal. Your stuff isn't setup right if you do.

 

[TeeLew]

If you install it directly as it's shipped, it will vent on basically every throttle lift in a city and most lifts on the freeway. Using the spring kit they they sell to tune their BOV, you can make it do what you want.

 

[ihasnostang]

are people assuming the air can't go back towards the airbox? i assume there is an expansion reason for the size of the tube reducing.

saw a video from throttle house that said surge under decel is okay, but during accel is bad

 

[Buldawg76]

Any turbo surge is a bad thing for turbines since it creates an imbalance of forces between the exhaust and intake turbine which if severe enough can break blades and shock bearings leaving detents in the races of the bearings which is sure turbo failure waiting to happen. If the BOV/BPV does not vent fast enough at 20-25 psi boost when the throttle is slammed shut its like hitting the blades and turbine shaft with a hammer. It will only last so long in those conditions.

BD

 

[ihasnostang]

in the case of "surge", the turbo experiences axial forces, OP's NX2 has ball bearings which are better with axial loads and don't require a thrust bearing like the OEM journal bearing turbos.



open throttle surge is very bad.

 

[Buldawg76]

As long as the axial load on the ball bearing is within the bearing axial load limits then they can be better but if the shock loads from the turbo surge hammering on the ball bearing it can detent the bearing races which will lead to failure.

It's the same as using an impact gun/wrench on a shaft that has ball bearing pressed on it to loosen a bolt or nut, the impact pulse from the gun/wrench will leave micro detents from the balls vibrating in the races that will cause the bearing to fail.

BD

 

[GJarrett]

Update. For a couple of reasons I ended up going with the Turbosmart dual port. The good news is that it fixed the surge. The bad news is that, even though it splits the vent between DV back to intake and BOV to atmosphere, the whoosh is still very apparent and it does it almost all the time. Since the dual port is ECU controlled I have asked my tuner if he can adjust it so it is not quite as eager to vent all the time. Will update later with the answer.

 

[Buldawg76]

Glad you got the surge corrected with the dual port turbosmart valve.

As far as venting issue is concerned anytime you are at steady speeds or off the throttle it is supposed vent the pressure that is present. So even at steady speeds there is some positive pressure being developed in the charge pipes that when it gets to a certain pressure the valve will vent. Ford does like to keep it on the edge of continuous transition area at steady speeds indeed.

Your tuner should be able to modify the strategy for the valve I would think.

I choose to go with stock BPV with the GFB DV+ kit versus the electronically controlled turbosmart valve. I am fully recirculated so if mine is venting at steady speeds I never hear it. Hard of hearing also. The GFB DV+ kit IMO offers better control of the BOV piston from the pressure differential between the charge pipe pressure and atmospheric at steady speeds. I have no experience with the TS valve so it may be just as good or better.

BD

 

[GJarrett]

I remember you suggesting the GFB DV+ earlier and I seriously considered it. Now that I have removed my stock DV and have confirmed that the o-ring is the correct color, I plan to go that route if I cannot get the excess atmospheric whoosh mitigated to my satisfaction. I'm okay with the swoosh during spirited driving; just don't want to sound like I am outgassing an 18 wheeler airbrake when I am leaving my quiet neighborhood.

 

[GJarrett]

My tuner did mitigate the whoosh at partial throttle so as long as I drive conservatively it stays quiet enough to get by. I am on the fence regarding whether to keep the dual port or not.

 

[Buldawg76]

Performance wise I don't believe you will see much if any difference between either setup. Just some noise difference at steady speeds. Bur as stated already have no experience with the TS valve.

BD

 

[GJarrett]

Yeah I was told there will be no performance difference... just sound consideration.

 

[ihasnostang]

does/did it sound like this?

 

[GJarrett]

...nothing like that at all!

Sponsored