Twin or single BOV on the RB26DETT???

[technorb26]

Hi everybody,

I have my car running, and I am boosting only 0.6 bar ( boost controller is not hooked up yet, I just ran a vacuum line from the manifold to the wastegates).I am using only one HKS SSQV blowoff valve. But when I rev it sitting on the parking lot, you can feel air going back through the intakes after I let off the throttle. So is one BOV enough? I know in Japan they run 2 BOVs.

Also, the car stalls a bit ( rpms drop to 600-700) every time you let off the gas. Does anybody have any recommended settings for the decel air function on the Apexi S-AFC?

Otherwise she runs great. Time for some suspenion work now, everything is sitting in my garage: HKS coilovers, SPL tension rods, Tein tie rods+ends, SPL rear toe arms, SPL traction rods, SPL RUCAs, 300zx calipers, 300zx rotors, brake lines etc etc

[gawdzilla]

congrats! hope you like the car.i dont see why you can't run just 1 BOV, as long as the spring is strong enough. if you're running recirc, I would get a Y-hose so it recircs back to both turbo inlets... just to keep things even.

[Ramius83]

Since you said your car is stalling, do you even have the one HKS SSQV recirculating to the turbos? If not, then that IS your problem all the way.

I bought a recirculation kit for my HKS SSQV, and ran a 1" hose from it to a Y PVC pipe that goes perfectly to the turbos. I'll take a picture next time I am near the engine.

[technorb26]

No, it is not recirculating. I know that is why it is stalling, but :- is one bov enough? If not, then air hits the hotwire on the maf and messes up the reading- since I have a S-afc and the mafs are hotwire type, I adjusted the decel air , but it still stalls. So I assume I need a second bov to make sure no air goes back through the intakes?

On my old 300zx tt, I adjusted the s-afc for the blitz BOVs, and it never stalled again.

Gawdzilla: the HKS BOV is a push/pull type, there are no springs, it holds whatever psi you throw at it. But if one is too small to vent the air out, you need 2 BOVs. Yeah, the car is nasty. At stock boost it feels to be over 300whp. It feels almost like my 300zx, that had 340rwhp. I still have to turn up the boost to 1.2bar, set my timing, and lean out the s-afc. It runs really rich, because of the walbro pump. I do not have an afpr, so base fuel pressure is at 47psi. The mods on the car are: intakes, HKS intercooler, HKS BOV, 4" exhaust, s-afc, HKS EVC boost controller.

[wawazat8402]

what is your ground clearance with the 4" exhaust?

what chassis is it on?

i am really wanting to go with a 4" but i dont want to kill my ground clearance.

[Ramius83]

One HKS SSQV BOV is PLENTY compared to the amount of boost pressure in your piping. I have seen MANY high horsepower Supras with a HUGE single top-mount turbo on them only using ONE HKS SSQV BOV.

I think that once your recirculate the air back to your intake, your problem will be almost completely solved.

But, what may be also adding to it is that you have a Walbro with NO afpr. On top of not recirculating, you are FLOODING the engine with fuel. This is what's creating your HIGHLY rich condition whenever you hold the clutch down or pop it into neutral, causing your engine to stall out. Even with the S-AFC in and having the DECEL air on, it still can't compensate for all that fuel in your cylinders because of not having the afpr.

[technorb26]

One HKS SSQV BOV is PLENTY compared to the amount of boost pressure in your piping. I have seen MANY high horsepower Supras with a HUGE single top-mount turbo on them only using ONE HKS SSQV BOV.

I think that once your recirculate the air back to your intake, your problem will be almost completely solved.

But, what may be also adding to it is that you have a Walbro with NO afpr. On top of not recirculating, you are FLOODING the engine with fuel. This is what's creating your HIGHLY rich condition whenever you hold the clutch down or pop it into neutral, causing your engine to stall out. Even with the S-AFC in and having the DECEL air on, it still can't compensate for all that fuel in your cylinders because of not having the afpr.

I agree, but I want to get the HKS fuel rail with an Aeromotive fpr, I do not want the Nismo fpr. I know that the HKS BOV kit for the Supra comes with one BOV, but the GTR comes with two.