Looking for help with possible issues with Recirculation valve

[NINJA GTR]

Was wondering if someone might be able to help me out. 

R33 GTR, everything is pretty much stock. 

For some reason while I'm lightly accelerating, it seems like my oem recirc valve is opening and closing making this constant whoosh sound. If I get on the pedal from that point it holds boost, but its really annoying when I'm cruising. If I'm cruising uphill, its bad enough that I have to pretty much floor it. It doesn't matter what gear I'm in. 

basically when I hit about 3k rpm I start hearing the whooshing noise and it wont let my turbo boost unless I get on the pedal. 

I cant imagine this being normal. 

I've also searched around and I cant really find information on anyone else having this issue. 

Has anyone else had an issue like this?

Edited April 2, 2024 by NINJA GTR

[Dose Pipe Sutututu]

Sounds normal to me, OEM Nissan BOVs open as soon as you're below atmospheric and there's ever so slightly pressure being generated by the turbos.

You'll probably get the turbo shuffle too from the two turbos pushing towards a single hot pipe too.

[Duncan]

If you have an aftermarket ECU, a log of AFM, Boost and TPS might help. 

But frankly, a standard GTR is no response king compared to a modern turbo car

[NINJA GTR]

 

Thanks for the response here.

Would getting a blow off valve (HKS SSQ) and recirculating it fix this issue?

Edited April 2, 2024 by NINJA GTR

[Duncan]

You can easily determine if it is actually a BOV problem by blocking off both valves temporarily and seeing if the issue still occurs....a blanking plate from cutting up a coke can is the traditional method.

[joshuaho96]

It might be the stock BOVs are done for? I don't think I experience this behavior which would be super obvious on expressway driving. ~3200 RPM going uphill getting into boost is really not unusual for these cars. It is very doughy around 3000 RPM.

Turbosmart makes direct replacements in the factory location that you can cap the atmospheric vents on as seen here: https://www.turbosmart.com/product/ts-0203-1072/

If you can actually diagnose it as failed I would probably go straight to those because they actually open all the way unlike the OEM valves which have surprisingly little travel.
 

Edited April 2, 2024 by joshuaho96

[NINJA GTR]

5 minutes ago, Dose Pipe Sutututu said:

Sounds normal to me, OEM Nissan BOVs open as soon as you're below atmospheric and there's ever so slightly pressure being generated by the turbos.

You'll probably get the turbo shuffle too from the two turbos pushing towards a single hot pipe too.

Thanks for the response here.

Would getting a blow off valve (HKS SSQ) and recirculating it fix this issue?

2 minutes ago, Duncan said:

If you have an aftermarket ECU, a log of AFM, Boost and TPS might help. 

But frankly, a standard GTR is no response king compared to a modern turbo car

Thats exactly how it feels, lack of response. 

I was going to go with N1 turbos and run the PFC L Jetro and tune it for the time being. I am starting to think it might not fix it. 

[GTSBoy]

Look for cracks in the signal lines running to the BOVs. They are long hoses and if you can vent enough air out of them (through cracks) you can cause a significant pressure difference between what the engine is seeing and what the BOV diaphragm is seeing.

900 year old Nissan OEM hoses lying in the bottom of the engine bay are as likely to be stuffed as anything else is.

[NINJA GTR]

3 minutes ago, joshuaho96 said:

It might be the stock BOVs are done for? I don't think I experience this behavior which would be super obvious on expressway driving. ~3200 RPM going uphill getting into boost is really not unusual for these cars. It is very doughy around 3000 RPM.

Turbosmart makes direct replacements in the factory location that you can cap the atmospheric vents on as seen here: https://www.turbosmart.com/product/ts-0203-1072/

If you can actually diagnose it as failed I would probably go straight to those because they actually open all the way unlike the OEM valves which have surprisingly little travel.
 

Got it, I'm glad I got a little bit of confirmation that a stock GTR should not feel like this. 

I will see if I can get aftermarket bov and recirculate it to see if it will make a difference. 

[NINJA GTR]

1 minute ago, GTSBoy said:

Look for cracks in the signal lines running to the BOVs. They are long hoses and if you can vent enough air out of them (through cracks) you can cause a significant pressure difference between what the engine is seeing and what the BOV diaphragm is seeing.

900 year old Nissan OEM hoses lying in the bottom of the engine bay are as likely to be stuffed as anything else is.

I'll do this first. It seems easy enough. I will hunt for the BOV line and see if it needs to be replaced. 

I appreciate all the help here. This forum rocks. 

[joshuaho96]

Just now, NINJA GTR said:

Got it, I'm glad I got a little bit of confirmation that a stock GTR should not feel like this. 

I will see if I can get aftermarket bov and recirculate it to see if it will make a difference. 

I agree with Duncan's advice which is start by capping off the the recirculating valves so they don't open and see if that fixes the issue. If that works you can start by replacing the rubber hoses. There's one hose that goes from the air chamber to the BOV in the fender which is going to be feeling for it blind. Then it branches off to a Y inside the fender and then two more hoses which shouldn't be too bad to figure out.

Keep in mind blocking the bypass valve will cause some weird behavior due to reversion so don't drive it like that too long.

[NINJA GTR]

2 minutes ago, joshuaho96 said:

I agree with Duncan's advice which is start by capping off the the recirculating valves so they don't open and see if that fixes the issue. If that works you can start by replacing the rubber hoses. There's one hose that goes from the air chamber to the BOV in the fender which is going to be feeling for it blind. Then it branches off to a Y inside the fender and then two more hoses which shouldn't be too bad to figure out.

Keep in mind blocking the bypass valve will cause some weird behavior due to reversion so don't drive it like that too long.

is there a write up or a video of how to block off the bypass valves?

[GTSBoy]

Just cut a shim from a coke can and insert it in the flange between the BOV and where it mounts. A gasket without a hole in it, if you will.

[Dose Pipe Sutututu]

And please don't get SSQVs

[Duncan]

37 minutes ago, NINJA GTR said:

......I was going to go with N1 turbos and run the PFC L Jetro and tune it for the time being. I am starting to think it might not fix it. 

I just wanted to comment on this. I run genuine Nissan N1 turbos on the race car as I am only allowed to use factory parts. They are horrible, 270o journal bearing turbos which are both laggy and unreliable (to be fair, they were state of the art in 1993). They come on boost at about 4,000rpm which is not impossible in race use but is about 1,000-1,500 rpm laggier than a modern alternative for the same target power.

There are plenty of good aftermarket options for low mounted twins which will look factory, but spare yourself the pain and don't go genuine N1s

[NINJA GTR]

48 minutes ago, Dose Pipe Sutututu said:

And please don't get SSQVs

GOT IT! haha

32 minutes ago, Duncan said:

I just wanted to comment on this. I run genuine Nissan N1 turbos on the race car as I am only allowed to use factory parts. They are horrible, 270o journal bearing turbos which are both laggy and unreliable (to be fair, they were state of the art in 1993). They come on boost at about 4,000rpm which is not impossible in race use but is about 1,000-1,500 rpm laggier than a modern alternative for the same target power.

There are plenty of good aftermarket options for low mounted twins which will look factory, but spare yourself the pain and don't go genuine N1s

Ok sorry for the confusion they aren't the N1, they are the older garret ball bearing turbos. I believe the garret 2860R part number 707160-7. I am praying they do not lag. 

Edited April 2, 2024 by NINJA GTR

[GTSBoy]

-7s are OK. Some lag, but not terrible.

[Dose Pipe Sutututu]

Inb4 Duncan has a sads

Convert to a single, twin scroll modern turbo.

[Duncan]

1 hour ago, Dose Pipe Sutututu said:

Inb4 Duncan has a sads

Convert to a single, twin scroll modern turbo.

you're a monster!

[joshuaho96]

11 hours ago, Dose Pipe Sutututu said:

Inb4 Duncan has a sads

Convert to a single, twin scroll modern turbo.

Let's just skip the middleman here and convince BMW to make a mirrored version of their B58 that is somehow direct fit for RB applications.