# Blow off valve



## Reedy (Dec 12, 2016)

Hi all,
i might get some stick, but i thought i would give it a try and fit one and if i don't like then i will just take it back off.
I've got a forge blow off valve, I couldn't find any guides on how to fit one.
http://www.forgemotorsport.co.uk/Blow_O ... --977.html

Heres my engine bay.


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## andys_tts (Oct 12, 2016)

I've got one on my TTS and love it. That's "_cheeeeshhh_" when changing gear and coming off the accelerator is fun. Your engine bay looks different to mine so can't help with the fitting. My OE valve is located slap bang in front of the engine bay. can't see one on yours.


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## Danaldsob (Sep 9, 2016)

VW/Audi cars are not meant to run blow off valves. they're not good for the cars.

the air is supposed to be fed back into the system. the only way you should be running a blow off valve if if you relocate your maf so that it is measuring the air properly instead of thinking the system has more their than its getting. because the air is being released to atmosphere.

Get GFB diverter valve. you will still hear the flutter that you want.


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## ldhxvs (Aug 18, 2016)

Danaldsob said:


> VW/Audi cars are not meant to run blow off valves. they're not good for the cars.
> 
> the air is supposed to be fed back into the system. the only way you should be running a blow off valve if if you relocate your maf so that it is measuring the air properly instead of thinking the system has more their than its getting. because the air is being released to atmosphere.
> 
> Get GFB diverter valve. you will still hear the flutter that you want.


There is nothing wrong with a blow off valve, they only blow off the air when the throttle is closed. Feeding the back into the system would be pointless when the throttle is closed... Bovs claim to combat turbo lag.


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## C00P5TT5 (Jul 10, 2016)

This may be of some interest.


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## Philx4 (Jul 12, 2015)

Take a browse on ECS tunings youtube video gallery; there will be something there I'm pretty sure:


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## Reedy (Dec 12, 2016)

Thanks all for you help.
I want to fit one and see if i like it, if i don't then i will just go back to standard.

I've seen that video but obviously they are using the relocation to fit it, i was hoping to find a video fitting in its origin position before relocating.

When the weather is dry i will have another look.

Thanks again


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## Dash (Oct 5, 2008)

ldhxvs said:


> There is nothing wrong with a blow off valve, they only blow off the air when the throttle is closed. Feeding the back into the system would be pointless when the throttle is closed... Bovs claim to combat turbo lag.


Nothing _wrong_ with them per se, unless your car is expecting a certain amount of air to be somewhere when it's not. Dumping to atmosphere when the car is expecting that air to be recirculated back to the turbo means your mix will be all off.


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## ldhxvs (Aug 18, 2016)

Dash said:


> ldhxvs said:
> 
> 
> > There is nothing wrong with a blow off valve, they only blow off the air when the throttle is closed. Feeding the back into the system would be pointless when the throttle is closed... Bovs claim to combat turbo lag.
> ...


Depends on your MAF and where it's located


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## andys_tts (Oct 12, 2016)

There have been numerous debates on BOV's, I read lots before I bought one.

Had mine blowing away for three years now and my car hasn't missed a beat. Then again, I treat it as a bit of fun and I'm not expecting it to make me go faster. I do remember reading that they suppose to help prolong the life of your turbo but that's just something I've read. [smiley=book2.gif]


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## FNChaos (Nov 30, 2016)

Audi uses a diverter valve instead of a blow-off valve to accomplish the same thing.
The difference is Audi's setup vents pressure back into the intake track instead to venting to atmosphere. This is done since the air that is vented has already been metered by the MAF sensor.
The other difference is Audi uses an electrical solenoid to control the valve rather than vacuum / pressure. This provides for a quicker response (and IMO, a more elegant design).

If your diverter valve is functioning correctly, there is no benefit to be gained by replacing it with a blow-off valve (other than a change in sound). If your diverter is defective, I would suggest replacing the diaphragm portion of the diverter valve with the kit made by GFBs (The GFBs kit uses a solid piston instead of a rubber diaphragm, and reuses your existing solenoid for control)


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## C00P5TT5 (Jul 10, 2016)

Second that. I have a gfb valve on mine and it has improved the performance but only marginal.... That said it will never need to be replaced again unlike the oem....gives a bit of wooosh but nothing like a blow off valve


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## C00P5TT5 (Jul 10, 2016)

Oh and if you are going to get a gfb valve make sure it's genuine..... Lots of fakes on eBay etc.

Got mine from Awesome GTI


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## Josherswilson (Sep 12, 2016)

I've fitted a Forge replacement valve, this didn't give the "wshhhhh" noise when letting off but as soon as i fitted a Ramair intake i got all sorts of induction and blow off noise


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## Sodde (Jun 1, 2015)

I recently replaced my diverter valve with a GFB valve and the difference was huge. I did have a very early version ('D' I think) but I was amazed at what I'd been missing. As mentioned, perhaps a newer OEM revision valve would have produced the same result. Anyone know what made the early version so bad? My 2012 TTS only has 10.8k miles!


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## Danaldsob (Sep 9, 2016)

ldhxvs said:


> Depends on your MAF and where it's located


Yes....and on TT's, the air is metered and if you use a BOV or spacer, you are allowing this metered air to leave the engine, and the engine will run rich. The only way you should be running a BOV is if you relocate the maf which is pretty pointless for a loud pshhh noise. You get plenty of that from the DV+ and an air intake. Your car will perform WORSE with a BOV.



Sodde said:


> I recently replaced my diverter valve with a GFB valve and the difference was huge. I did have a very early version ('D' I think) but I was amazed at what I'd been missing. As mentioned, perhaps a newer OEM revision valve would have produced the same result. Anyone know what made the early version so bad? My 2012 TTS only has 10.8k miles!


The early versions (Revision G) used a plastic piston and a rubber diaphragm. This revision performed well, but typically tore very early.

the later style (revision D) replaced the rubber diaphragm with a plastic version which was much more durable, but didn't perform the best. they are known for leaking and not being very responsive.

It doesnt matter which version you use with the DV+ because they only use the solenoid, not any of the internal parts. Both revisions use the same solenoid.


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## ian222 (May 4, 2007)

I am gonna try it out, so many mixed reviews. If it works the same as the split r on the mk1 tt it will come off.


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## bertiebowser11 (Mar 13, 2017)

ive done it, the forge spacer sounds epic, a mates saab maf doesnt like because of its location. Ill upload a video as i promised to do a while ago, its sounds amazing, doesnt give anymore performance just a grin, i spoke to forge and they have sold 10's of thousands for the TFSI its literally a spacer that goes on the diverter valve, I then also saved myself on cat back and removed the whole system, removed the baffles, welded the centre section baffle that is actually split, weld it together with stock end, and now loads of wastegate noise and chatter from the forge spacer, total cost £50, looks and sounds mean but not OTT.

ill upload a vid


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## bertiebowser11 (Mar 13, 2017)




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## bertiebowser11 (Mar 13, 2017)

wastegate noise is almost louder the BOV but the chatter when your in or passing is amazing


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## bertiebowser11 (Mar 13, 2017)




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## bertiebowser11 (Mar 13, 2017)




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## bertiebowser11 (Mar 13, 2017)

this is such a huge topic on the spacer BOV, i have not noticed a single bit of difference in performance, maybe i lose 3bhp who cares it sounds fabulous, it may not be ideal, as in no gain, but i dont see the down side, we want these for sound satisfaction only.


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## ian222 (May 4, 2007)

I know it does seem a topic of debate this one. Can't really hear it on your vid of you driving.


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## Sodde (Jun 1, 2015)

I would have to say that the benefits of the GFB diverter kit I noticed immediately has nothing to do with power or noise it was the smoothness of pickup from low revs and better pick-up after lifting of throttle.
Prior to this, the pull from low revs was like pulling away in 3rd gear and the turbo would kick in harshly at 2-2.5k.

just better and more progressive to drive now.


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## bertiebowser11 (Mar 13, 2017)

only thing that forge said to me about the BOV spacer is that the diverter valve will fail eventually, but was more of a rubbish design in the first place so worth doing at the same time. it doesn't throw any engine management issues, I havnt noticed a difference in performance and it hasn't broken anything yet. Touch wood


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## Job (6 mo ago)

bertiebowser11 said:


> ive done it, the forge spacer sounds epic, a mates saab maf doesnt like because of its location. Ill upload a video as i promised to do a while ago, its sounds amazing, doesnt give anymore performance just a grin, i spoke to forge and they have sold 10's of thousands for the TFSI its literally a spacer that goes on the diverter valve, I then also saved myself on cat back and removed the whole system, removed the baffles, welded the centre section baffle that is actually split, weld it together with stock end, and now loads of wastegate noise and chatter from the forge spacer, total cost £50, looks and sounds mean but not OTT.
> 
> ill upload a vid


Hi I am just about to get my self a BOV. For my tts are you going to up load the vid so I can see if it’s any good 😊 thanks for your time 
Regards 
Simon


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## FNChaos (Nov 30, 2016)

Job said:


> Hi I am just about to get my self a BOV. For my tts are you going to up load the vid so I can see if it’s any good


You are responding to a thread from 2017.
Bertiebowser11 hasn't been on the forum since Jul 30, 2021.

Why do you want to replace your diverter valve with a blow off valve? Your car already has a better, more elegant solution.


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## Job (6 mo ago)

FNChaos said:


> You are responding to a thread from 2017.
> Bertiebowser11 hasn't been on the forum since Jul 30, 2021.
> 
> Why do you want to replace your diverter valve with a blow off valve? Your car already has a better, more elegant solution.


Ok thanks for that , well it’s saved me some money, appreciate your opinion 
Regards 
Simon


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