OK boys and girls, there have been a lot of posts about BOVs recently and at least two threads laughing at the the electronic "sound-only" pt-schhhh noise makers.

 

Here is a very reasoned analysis of what BOVs do, and why Re-circs are better and how to install them. http://www.twinturbo.net/ttnetfaq/FAQpages/bov.html

 

This applies, according to the author, up to about (guess) 600hp. Serious tuners have the experience / knowledge to judge exactly when is right to use BOVs for their engine instead of recircs.

 

Otherwise, recirc + noisemaker is a better / more reliable / cheaper mod than BOVs. If you want the noise. According to this lot. Discuss :D

 

(If you just want the performance and you're going from anything between stock bhp and the 600-ish guesstimate, fit the recircs in the article in the link)

We all now really that most engines built with recircs are much more efficient than bovs, bovs are just for noise, unless you are running such high PSI and the turbos are plummed in such a way that when the TB is closed it will create back pressure also on the turbo damaging the turbine, but IMHO that is questionable. Under serious PSI it can stall the compressor because of the back pressure, but thats it. I've never seem a damaged comperssor due to this.

 

99% of DV / BOVS fitted are just for the noise.

 

So I would say, if you want to pay for a noise then go for a DV / BOV, if you want your car to run well and like its meant to then use recircs (unless you have spent in excess of 10k and need a wastegate / bov to bleed the EXCESSIVE amount of pressure).

Mine are there for 2 reasons.

 

1. Don't like goose honk

2. Like the noise they make when you are attacking a welsh mountain road on and off the throttle.

 

Plus the APEXi ones look really high quality so you can think about that when your driving along skint after paying £300 for them. :rolleyes:

Goose honk (which can e fixed) and performance vs granny scarers and lesser performance

 

Mmm toughy

 

Ill take the recircs

 

99% of DV / BOVS fitted are just for the noise.

QUOTE]

 

Too true :)

Finally fitted my ApexIs at last!!! :hyper: DEFINATELY a head turner. I've not yet seen how it affects my perfomance but it's idling's all over the place. Miss the stability of the recircs, love the sound of the BOVs. As that rap artist said: "What about now, I'm 50/50"...

I have Blits Dump Valves would i get much better performance from Recircs and where do i get them from and how do you fit them.

i love the sound of a dump lol :rofl:

i dont go flat out everywhere to notice loss of power if any from bovs

Finally fitted my ApexIs at last!!! :hyper: DEFINATELY a head turner. I've not yet seen how it affects my perfomance but it's idling's all over the place. Miss the stability of the recircs, love the sound of the BOVs. As that rap artist said: "What about now, I'm 50/50"...

 

Sounds like you've got a slight leak back through the valves under high vacuum - hence rough idle. I think you can stiffen them up so they'll stay shut - but it's then harder to open them so you won't get quite as loud a noise.

 

Have to say with TurboTechnics Stage II and a Blitz SUS - but with STOCK recircs - the air moving around was quite loud enough anyway. :D

 

I'm thinking of putting some Baileys recircs on the TDI...

hi skylinedave

 

You say you have eratic idle now after fitting the valves??

zevans is right with the leak bit, the springs in the valves that control the the pistons movement need stiffening up, i have the Turbo XS RFL dump valves fitted to my Z they come with packing washers to stiffen the spring inside them, and the instructions that come with them state that they should be packed if the car idles erractically.if you do this im sure it will be as it was with the recircs, i have not noticed any difference in perfomance, just tend to let off the throttle more these days so i can scare someone. Not sure how the apexi's are made but mine just unscrew??

and are made up of the top/bottom sections a 6inch spring and a brass piston, thats it.. very simple and far too expensive......

gunn and zevans: hi and thanks for the advice. when i first installed them (the instructions barely mention the adjustable screw) i had major problems - it stalled after every dump no matter what rpm. after *loosening* them with a few twists of the screw it behaves much better - the dump is less aggressive, but it only stalls when i foot-off after high revs (say over 6k). during 'normal' driving ( ;) ) revs tend to dip low after the bovs actuate (the higher the revs, the lower the dip!!!) - sometimes even to 100/200ish and near-stall. idle is much much better now tho - when the engine is warm it idles as low as 500!!! (sounds like an old mustang!)

however i'll try tightening the screw a) back to normal and b) even tighter than normal, then take the car for a few blasts around the block to see what happens - i'll let you know.

Cheers for now,

Dave. :)

Just a thought, couldn't the re-circ valves be used as dump valves? Assuming of course that you want to reduce the engines performance ;)

Just a thought, couldn't the re-circ valves be used as dump valves? Assuming of course that you want to reduce the engines performance ;)

 

Yes!

Just a thought, couldn't the re-circ valves be used as dump valves? Assuming of course that you want to reduce the engines performance ;)

 

 

yeah, Phil at C&S Wood thinks they can. Cut the return hose from the recirc valve, leave the recirc side of the hose open and block the other side so nothing gets into your engine.

I tried that and it just kept on stalling. it was drawing air in threw the re-circ not sure why. :confused:

 

This is where i find out i have 2 faulty re-circ valves.