I have now installed two blitz bov's on my z.

 

The problem is throttle a now not as smooth as it was with the recircs. For example if I plant my foot and build boost only to about 5psi and slowly release the throttle the car jerks. I assume this is because of the measured air isn't being matched by actual air, correct?

 

Others with bov's must have experienced this? I am planning on having the car mapped soon on a rolling road, will this eradicate the problem?

 

Thanks, Dan

Ok, I understand though that this can be detremental to the lifespan of the turbos?

My turbos are going to die of being at 16psi long before they die of the surge. But both of these things make me grin till it hurts, a small price to pay. You are totally right but I think it would take a lot of miles to do it. Noz uses a full closed system, because it sounds ace :biggrin:

Ok, so with these kits then obviously they have a stronger spring that let's go of boost at what psi? I am guessing that yours dosnt flutter when 16psi is dumped? So at what psi does the flutter quieten?

 

Thanks

Its not one of those multiple second "wha-ch-ch-ch-ch..." type flutters. Its more like a squeaky sneeze. I'd have to pay closer attention but it does it most noticeably at 16psi and a bit at any positive boost pressure below that.

 

It must be so stiff that even at 16 psi it doesn't fully open the recirc valve. But even if that's because Mark somehow put them together wrong, I wouldn't have it any other way, it runs beautifully.

Edited June 25, 201411 yr by tomfromthenorth

The boss has let me practice for TOTB on the taxiway behind the hangar. You can just hear it on the first gear change. In real life its clearly audible. But look at the responsiveness and how smooth it is.

 

Going down the runway at work.: http://youtu.be/IR229dZKq88

Cheers, looks like I shall be investing in those then..

Try stock recircs first, and if they make a noise like blowing over a milk bottle too then get the BDEs :) otherwise save the 60 quid or whatever they were. Apart from the bloody howling resonant honk the stock recircs drove really well too.

Yea my stock recircs drove fine but were silent..

ill have to upload a video of my car, its induction road is incredible, as well as the compressor surge, it literally sounds more like a modded supra than a 300zx. Sounds like no 300zx Ive ever heard, if you like the sound i'll post the specs.

 

But it does run split intakes, with dual dump valves too :)

Si, I know you have said before that dump valves sound like a scania's air brakes, I have recircs, I bought the kit to get rid of the goose honk and an unexpected side effect is surge. I Can't do right for doing wrong haha I thought it would be the one part of my car you would approve of!

 

I have aftermarket recircs. Recircs are by far and away the best thing to keep on the Z when running standard management. What is disapproving about what you've done and where did you get the impression that I was!?!?!?! lol

If I put my recircs back on, (that are silent) how is it these kits can get noise out of them? I can't get my head round how they can make the stock recircs noisy?

 

Thanks

 

What noise are you after? The wastegate chatter / chirp is generally heard when you fit a cone filter and up the boost a little. It has nothing to do with the valve itself.

What noise are you after? The wastegate chatter / chirp is generally heard when you fit a cone filter and up the boost a little. It has nothing to do with the valve itself.

 

The noise becomes even more apparent when you close the system completely. As mentioned, theoretically it's no good for the turbos but how much of a difference it make to the longevity, who knows! I know people with other marques using a closed system for years without issue covering 10,000s of miles.

I have aftermarket recircs. Recircs are by far and away the best thing to keep on the Z when running standard management. What is disapproving about what you've done and where did you get the impression that I was!?!?!?! lol

 

My nose isn't out of joint :) I thought the air brake sound clip came after my post and just thought "haha, the one part of my car that isn't against the code of OEM+ Funky Si modifying."

T300zx yes a video with specs would be great.

 

I now know I can't drive much longer with these Blimming atmos bovs, i have two options, buy the goose honk deletes or blank the valves altogether..

 

Btw I already have a mushroom filter installed, and with the stock recircs it is still deadly silent on throttle release..

Sensible and BEST option is get rid of those pointless dump valves, refit the recirc valves, either with known good ones or with the BDE goose-honk killer kit. I personally would not blank off the recircs at all. If you say your recircs were 'silent' then you don't need the BDE goose-honk killer kit. It would make the unit a little better, but if you haven't already got goose honk, then you don't really need them.

 

- - - Updated - - -

 

My nose isn't out of joint :) I thought the air brake sound clip came after my post and just thought "haha, the one part of my car that isn't against the code of OEM+ Funky Si modifying."

 

Someone asked for a video of the dump valve noise, I gave them a video of a noise that sounded like a dump valve! :lol:

Are you running standard boost?

Standard at the moment yes. Wouldn't plugging the vacuum lines have the same effect as blanking the system? I would like more noise, so probably will go with the ghk kits with standard recircs, plus it's there then for when the car is mapped by Noel.

 

Where is the best place to buy the kit from? The link that was posted earlier? Or another supplier in the uk?

 

Thanks

Why do you want to plug and blank parts of the system that the car uses as metered components? I don't get it.

 

So standard boost. When you increase the boost, the wastegates will open more. You'll notice more of this 'chirp' when you do that.

I don't, I'm just suggesting that would have the same affect? It's running 10psi

Putting restricters in your vacuum lines will help. This is essentially the boost jet mod (which will increase boost). I wouldn't plug them.

Standard at the moment yes. Wouldn't plugging the vacuum lines have the same effect as blanking the system? I would like more noise, so probably will go with the ghk kits with standard recircs, plus it's there then for when the car is mapped by Noel.

 

Where is the best place to buy the kit from? The link that was posted earlier? Or another supplier in the uk?

 

Thanks

 

 

Mine are probably louder because:

I have increased boost.

2.5 inch hard pipes.

Split intake.

2 Cone filters.

The recircs are really high up probably more audible if they make any whooshes (which although they shouldn't they're still moving compressed air through pipes.)

BDE GHKs which are causing some surge.

An exhaust that doesn't mask it with BOOM!

 

So you aren't guaranteed this vvvv from the GHKs

 

 

And mine sounds more like a "Pow!" sound than that Quattro.

Edited June 26, 201411 yr by tomfromthenorth

It's not the recircs that are making the noise. They should make no noise at all. The noise will come from the wastegate which is heard as a result of increased boost and that noise is made more audible by fitting cone filters which remove the sound dampening forces created by the stock air intake.

How is does the wastegate noise on the exhaust side get into the inlet side?

Ignore! I was reading the read about induction 'roar' when I wrote it! Got my tubes cross! :p

What's making the noise? Turbo stall?

 

With the GHK fitted, compressed air being suddenly released back into the inlet track.

 

Compressor surge = uncontrollable turbine overrun. Example video:

 

[video=youtube_share;nCj6Spwl1CU]

 

Compressor stall = back pressure through compressor turbine when throttle is closed from WOT.

 

The stock recircs are primarily there to prevent compressor stall and so improve drivability:

 

http://www.twinturbo.net/nissan/300zx/FAQ/FAQpages/bov.html

 

By the way read "stall" for "surge" in the FAQ!

Edited June 26, 201411 yr by AndrewG