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

It might be that un metered air problem, but could also be knackered if second hand and leaking or not doing what they should be inside.

 

I reckon a map could make it better but I don't think you can ever totally sort the problem unless you moved the MAF/s nearer to the throttle bodies.

Cheers, the car holds boost fine. The valves are in the same place as the original recircs were...

seems some people have no issue with bovs and and other have lots of probs . are they duel piston or single piston google it and you we see what am talking about

Ive got twin baileys on mine and its very smooth

I used to have Apexi BOV,s on mine and iff i nailed it then brought it to a instant stop i would get a slight flutter but nothing like described....have you set the springs up right on them? as they do sound like there lifting a bit early.

I have just been out in it again, If I accelerate and let the boost gauge rise but keeping it in the vacuum and slowly release the throttle it's the same; jerky, as though it's missing..

 

The screws are adjusted fully out on each. I guess I should wind them in a bit and see if that improves any.

 

Thanks

Refit the recircs, you know it makes sense. :)

I admit it would be the sensible option.

 

I have wound each screw all the way in and went for a drive. Driveability has improved with power delivery much smoother. When the car boosts 10psi there is a very very quiet whoosh noise as the throttle is relased. Anything less than 10psi results in compressor surge.

 

I guess I need to find the happy medium and set these bov`s up as best I can.

 

Any advise in how to do this?

 

Even when these are set up correctly I am guessing there will always be some compressor surge on part boost??

 

Thanks

so it just about releasing the air then at 10psi and below that the spring tention is to high for lower boost levels so hence you get the surge. you need to be able to bump at higher and lower psi most dump valves are fixed at a given psi. I have a set am going to use hks Sequential Blow Off Valve thay don't work like a regular dump valve http://www.hks-power.co.jp/en/product/blow_off/sqv/

I am still having problems with these valves running my car rich at throttle release. I understand it because of the maf but it almost makes the car undriveable when coming off the throttle slowly...

 

Surely others with atmospheric bovs must have experienced this?? Does a remap smooth out this miscalculation of air and fuel on throttle release??

 

Thanks

is the spring tenstion on full now

There are 11 full turns of the adjustment screw. I have tried them all the way in, all the way out, 5.5 turns in, 7.5 turns in and 3.5 turns in. All this does is adjust the tension of the spring, it is not helping the drivability/smoothness coming off the power.

 

I can only assume my map dosnt support atmospheric bovs..

 

Thanks

the lack od smoothness I bet is coming form then valves now opening or opening to early the prob is you can only set them at on tention setting. also since you have been messing around with the intake pipe work you may have a boost leak doing a boost leak test after messing about with the pipe work would be a very good idea

I did a boost leak test after the fmic was installed as I couldn't get the car to boost correctly, what leaks there were have been fixed..

but have you done a leak test with the valves fitted you may not have had one then but you could well have after fitting valves or the valves them self worth doing as its easy and would be one thing you can rule out

In theory if you vent any air at all it will run rich. Some people's cars seem to get away with it, mine didn't at all. It wouldnt even idle unless you had the air con on. Recircs all the way, I have the BDE goose killers and they sound awesome. "Kssssk-chirrup" like a Quattro.

The bde what now?

 

I guess it could be leaking again, got be worth a check I guess

http://bde-performance.com/goose.htm

 

Those

Ok, i am intrigued to how they sound? Is there any clips on YouTube that show a similar sound to yours? What's making the noise? Turbo stall?

 

Thanks

Ok, i am intrigued to how they sound? Is there any clips on YouTube that show a similar sound to yours? What's making the noise? Turbo stall?

 

Thanks

 

@ 1.00

 

[video=youtube_share;Tf0sk7g6-Wc]

I think Tom's over egging it a bit there with "Kssssk-chirrup", my BDE recirs are more "Pssst Pssst".

@ 1.00

 

[video=youtube_share;Tf0sk7g6-Wc]

lol I like the dump sound if am honest I woulntd fit one to my bmw x5 that's a turbo but in a z for a blast for half hour then yes just a but of fun

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

I promise mine give a bit of compressor surge. They go Kssssk-chirrup.

 

They are now not recircing all the air, some of it just goes back through the turbo blades and surges and makes a noise like throwing a budgie through an office fan.

 

Mark, mondo, Dave back me up :lol:

Edited June 25, 201411 yr by tomfromthenorth

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!