Rb25Det Stock Bov Leaking?

[Ultimategtr]

Hi All,

I dont drive my car often, maybe once a week, if that, and its only short runs.

Today I noticed a much more flutter sound on high boost. On Low, 10psi, hi 16psi.

Car's been tuned with a Link G4 for up to 18psi but I've decided to run around 16. Usually, while on high boost, I would notice a slight flutter.. to me, it sounded like a leaky bov. Today, I drove it and it was MUCH louder.. to the point that my boost gauge was jumping between 15-18psi when under load(WOT).

My question is - HOW do you tell if your BOV is leaking? is there any telltale signs??

The stocker is always open at Idle, and under boost, it is shut by the boost.. so I dont see how it is leaking.

I dont think its my boost controller/spike/creep, but I have turned the boost down(pointless though). I want it to hold 16psi solid.

Any help would be muchly appreciated

[wolverine]

What turbo are you using?

[KiwiRS4T]

What are you using for a boost controller? As you have a Link G4 you just need a Mac solenoid valve and the G4 can do sophisticated boost control.

Have you checked the vacuum line to the bov?

Is there someone nearby you could swap with for a test?

If you decide the bov is faulty I have a pair of GTR bovs which are much more robust than the RB25 ones and bolt straight up in the same place (although you need to adapt the outlet pipe as the GTR one is bigger).

I am after $100 for the pair posted but could do you one for $60 posted.

[Ultimategtr]

Thanks Kiwi! I just might take you up on that offer, for the one. Give me a week to have a play around. I'll see if I can borrow my mates to test.

My turbo is rated @ 300kw, and is a hybrid by steve murch. Im using a Gizzmo MS-IBC. I did use the onboard link boost control, but I decided to switch back to the gizzmo as I had probs with boost(was caused by the actuator not opening). I do plan to go back to the Link Boost control though, will need to get soichi to set it up, needs another dyno run though.

My bov currently is recirculated back - mainly because I will need a catch can, which is something I havent bought yet, if that makes sense.

I have checked ALL the vac hosing, its fully tight.

[51NNA]

It's nothing to do with your BOV, sounds like your turbo's surging. Try lowering the boost and see what happens, I assume its all stock pipe work to the plenum?

Edited May 12, 2012 by 51NNA

[Ultimategtr]

Turbo is surging.. please explain?

[51NNA]

Turbo charger surging may be defined as a high pitch vibration of audible level coming from the blower end or compressor end of the turbocharger. Whenever the breakdown of gas flow takes place, a reversal of scavenge air takes place through diffuser and impeller blades into the blower side which causes surging. Surging is to be avoided as it interferes with the combustion in the main engine and may cause damage to the thrust bearings.

Therefore, the turbochargers are needed to be matched properly with the engine air consumption rate and pressure across the operating range of the engine and they should not fall in the surge limits.

TLDR.

The turbo is producing more air then the engine/intake can take.

Also caused by a restrictive exhaust.

Edited May 13, 2012 by 51NNA

[wolverine]

The turbo sounds like a bitza and this is almost certainly the source of your issue. Compressor surge is common when you have a relatively large compressor vs small turbine.

What more can you tell us about the turbo? Is it is hi-flowed stock turbo?

Do you know anyone else with the same turbo? Do they have the same issue?

[Ultimategtr]

I dont see how the turbo might be the issue. Actually, I dont believe that for a second, however thanks for pointing that out.

If it was the turbo, it would have been obvious on the dyno, when it was being tuned. This started a few weeks after that really.

I turned the boost down to 14, and it was better, but still happened, not as bad as before. I will hunt for a replacement bov. Thanks!!

[methz]

how is the stock bov shut by the boost at wot?

[Mitcho_7]

how is the stock bov shut by the boost at wot?

The vac line that connects from the plenum to the top of the blow off valve helps keep it shut

Edited May 13, 2012 by Mitcho_7

[89CAL]

The vac line that connects from the plenum to the top of the blow off valve helps keep it shut

Yeah Spring pressure + Manifold pressure will always be greather then boost pressure (when you are WOT anyway)

Edited May 13, 2012 by 89CAL

[wolverine]

I dont see how the turbo might be the issue. Actually, I dont believe that for a second, however thanks for pointing that out.

If it was the turbo, it would have been obvious on the dyno, when it was being tuned.

Compressor surge is most evident on light medium throttle openings, you might not experience it on the dyno.

If you don't want to explain what housings your turbo has used then it is your prerogative. Good luck.

[51NNA]

Today, I drove it and it was MUCH louder.. to the point that my boost gauge was jumping between 15-18psi when under load(WOT).

This is what happens when a turbo surges...things change from dyno to road for example a 760KW 1UZFE with twin GT3576's that we tuned didnt surge on the dyno yet at powercruise and on the strip it surges badly, though its running 38psi...

Edited May 13, 2012 by 51NNA

[Ultimategtr]

I see what you mean. Im saying that it didnt happen before. I had it tuned in January, and it didnt do this before. I got the tuner to test drive it as well and he said no issues at all.

Ah well, I'm going to start by the cheapest option - Replacing a turbo isnt that cheap, lol, but hey, you might be right..only one way to find out eh? Cheers for you guys help so far!!

[51NNA]

The turbo itself wont need replacing, what size exhaust do you have? what size intake pipe do you have?

[The Mafia]

don't even help this fool if he is ignorant and won't accept that there are other possibilities than of what he thinks.

Don't even know you posted if you're not willing to hear from people with a lot more experience and that have dealt with this problem a hell of a lot more times than you have...

[Ultimategtr]

don't even help this fool if he is ignorant and won't accept that there are other possibilities than of what he thinks.

Don't even know you posted if you're not willing to hear from people with a lot more experience and that have dealt with this problem a hell of a lot more times than you have...

At what point do I seem ignorant? I'm sorry if seem ignorant, but I was just stating what I was experiencing.

I dont appreciate being called a fool, so careful with your words mate.

[skylinecouple]

Try the BOV 1st, if no change then report back. The question has been asked, how big is the exhaust ? Is there a decent dump pipe to allow the new turbo to flow better into a (hopefully) free flowing exhaust and cat. Have you still got the original rubber intake that may colapse under boost then spring back into position so you will never find the problem? There are people here who can tell you exactly what the turbo will behave like if you give them the wheel sizes used in the turbo.

If you say the car was driving fine before then perhaps you are correct, it may be the BOV. Please remember people here really want to help, these cars are their passion, not just a mode of transport. Answer some simple questions and the problem will eventually be diagnosed.

Are you still using the original actuator ? They can only hold so much wastegate pressure. Try a 14lb actuator and see how that goes. They can be had from the States for $30. Or for a simple test try putting an external spring on the wastegate lever and slowly add more throttle while going up a steep hill. Don't floor it as you may over boost and here loud noises from under the bonnet. Watch your boost and see if it is stable. If so, then there's your answer, the waste gate is creeping open then closing then opening.

[Ultimategtr]

Try the BOV 1st, if no change then report back. The question has been asked, how big is the exhaust ? Is there a decent dump pipe to allow the new turbo to flow better into a (hopefully) free flowing exhaust and cat. Have you still got the original rubber intake that may colapse under boost then spring back into position so you will never find the problem? There are people here who can tell you exactly what the turbo will behave like if you give them the wheel sizes used in the turbo.

If you say the car was driving fine before then perhaps you are correct, it may be the BOV. Please remember people here really want to help, these cars are their passion, not just a mode of transport. Answer some simple questions and the problem will eventually be diagnosed.

Are you still using the original actuator ? They can only hold so much wastegate pressure. Try a 14lb actuator and see how that goes. They can be had from the States for $30. Or for a simple test try putting an external spring on the wastegate lever and slowly add more throttle while going up a steep hill. Don't floor it as you may over boost and here loud noises from under the bonnet. Watch your boost and see if it is stable. If so, then there's your answer, the waste gate is creeping open then closing then opening.

Cheers mate for the suggestions. I understand people are trying to help, but its some dim witted people and their responses which usually derail a thread.

Exhaust is a 3.5 Tomei Dump, Front, and a full 3.5~ inch catback with a 5inch tip, so the exhaust isnt restricting flow at all. Using an R32 actuator(10psi). Cant remember the specs of the turbo wheels.

Doh - the rubber hose MIGHT just be the issue too.. I already have a alloy metal intake pipe sitting at home. The story is - I havent put it on, as I will need to remove the recirc piping, which is connected to the top of cam covers, and for that hose to come off, I will need a catch can.

I will change the bov and install the metal pipe this weekend, and will get a catch can too, that should fix it.