# GFB Blow off valve



## DWC (May 18, 2009)

Chaps

Can anyone confirm that these will fit my 35. I read somewhere that the 34 ones are the same fitment. And are they easy to fit ?

GFB Application Specific Repsons Blow Off Valve - Demon Tweeks

Oh and will i need a remap.

Thanks

Dave


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## Takamo (Oct 18, 2005)

They look similar but I think that is for one not a pair because it says quantity one


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## DWC (May 18, 2009)

Ah ok. I think I want the GFB ones as the Forge ones are a bit weedy. I want a proper boy racer whoosh lol ha ha


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## Takamo (Oct 18, 2005)

Nope!! I've just a set of forge trumpet style blow off valves fitted and they sound awsome.. Much louder than I thought so it's upto you


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## Sinth (Sep 26, 2010)

Takamo said:


> Nope!! I've just a set of forge trumpet style blow off valves fitted and they sound awsome.. Much louder than I thought so it's upto you


Can I ask where you bought them from?


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## DWC (May 18, 2009)

Dunno but I need to get Dumping either way. Your fault Steve !!


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## andrew186 (May 3, 2010)

i have had both and can confirm that the GFB is much louder

give SVM a call for the GFB's they can post it out to you next day .. and i think you will find their pricing much better than off that website (thats what i did  )


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## Takamo (Oct 18, 2005)

I got them from Lichfields and they were slightly cheaper than GFB ones and they come complete as a kit with the block off plugs and they are adjustable and come with extra springs, trust me they sound awsome worth every penny


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## Julesthecat (Feb 15, 2012)

I fitted gfb BOVs in my 09. 
Easy to fit (it took about 10mins each)
They come with good instructions on setting the spring and setting the ratio between recirc and vent to atmosphere- I have mine set to around 60% recirc. 
They don't require a remap - I checked this with Ben at Gtc and he confirmed this. 
Aim to pay around £300 for the pair.


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## DWC (May 18, 2009)

Thanks Guys i'll look into it.


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## DWC (May 18, 2009)

Yep well got them fitted today and there awesome. Having a slight prob setting the spring rate correct though. Should the valve be fully shut when at idle. I need to wind the nut right in to get them to fully close. Might be me but at low revs the car stumbles very slightly sometimes when coming down the revs. Sounds great though. Glad i went for the GFB ones. Just needs fine tuning.


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## Julesthecat (Feb 15, 2012)

The springs on mine are not at 100% - i reckon about 80%-90%. The top of the tightening screw is 2.5mm below the surface. The valve should close fully (when viewed thru' the trumpet) after you give it a good rev. It should close in a single smooth (but reasonably slow) movement. 

Once that looks fine then check your revs. They should fall back to idle without dipping momentarily below when you lift off the accelerator. 

Also - make sure your AirCon is switched off when testing/adjusting it. 

Also, what percentage vent to atmosphere have you it set to? I'd be inclined not to have it above 70% so that you get some recirculation. Im not an expert on this point but it would seem sensible.


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## ChuckUK (Jan 1, 2009)

You guys not noticed any decrease in turbo response ? what about over fuelling now that air has gone from the system ?


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## Julesthecat (Feb 15, 2012)

Small positive difference in turbo response, but I don't drive it very hard. 

I don't believe over-fuelling is a potential issue as (a) it's a hybrid system that recircs initially before venting and (b) it's only venting when you lift-off the throttle. 
Perhaps if you are ramming it up thru the gears you might get some overfuelling between gear changes, but I've found that with the vent to atmosphere set at around 50-70% it only "whooshes" when you accelerate and then lift off, and not between normal gear changes. 

The fact that you can "dial in"up to to 100% recirc means you could probably test whether there is a point at which one's particular driving style causes any over-fuelling issue and set the dial to the level that doesn't cause it.


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## Voyager (Jul 20, 2012)

i used to love that noise years ago, but i feel i am getting a bit old for the "whooshpah" and the attention it attracts, stealth is the new black dont ya know


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## alloy (Apr 29, 2005)

I have the GFBs, noise isn't obtrusive, have not noticed any difference in performance and drive but i'm told they help maintain boost.....at worst they're harmless fun, at best there's some benefit....go for it


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## New Reg (Jul 22, 2011)

Voyager said:


> i used to love that noise years ago, but i feel i am getting a bit old for the "whooshpah" and the attention it attracts, stealth is the new black dont ya know


+1

IMO BOV's don't belong on a GTR, no more than a Sub the size of a dustbin lid does, or neon lights for that matter. To each his own though.


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## Julesthecat (Feb 15, 2012)

My wife tells me that I'm about 5 years behind the fashion, so that's about right. 
Since this is my midlife-crisis car, I'm going for the bells and whistles. When the arse eventually falls out of the GTR, I'll probably be back to a boring Beemer, so I'm making the most of it now. If you time the whoosh right then you can see pedestrians give a little jump - and, sadly perhaps, that's my idea of fun


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## misters3 (Jun 23, 2008)

New Reg said:


> +1
> 
> IMO BOV's don't belong on a GTR, no more than a Sub the size of a dustbin lid does, or neon lights for that matter. To each his own though.


I'd better get a bigger sub, neons and these bov things asap


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## saucyboy (Nov 1, 2009)

I really fancy a pair of these. Now i just need to convince the wife that they are needed lol.


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## Henry 145 (Jul 15, 2009)

Takamo said:


> Nope!! I've just a set of forge trumpet style blow off valves fitted and they sound awsome.. Much louder than I thought so it's upto you


+ 1


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## DWC (May 18, 2009)

Julesthecat said:


> The springs on mine are not at 100% - i reckon about 80%-90%. The top of the tightening screw is 2.5mm below the surface. The valve should close fully (when viewed thru' the trumpet) after you give it a good rev. It should close in a single smooth (but reasonably slow) movement.
> 
> Once that looks fine then check your revs. They should fall back to idle without dipping momentarily below when you lift off the accelerator.
> 
> ...


Thanks so much for your help matey. Iv now got them running smooth. Wound the spring in like you say and the flutter at low revs seems to be gone. At full Atmosphere at the moment as im enjoying frightening people to death. So funny. Whatever blows your skirt up i suppose.

Dave

Pics to follow.


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## DWC (May 18, 2009)

Couple of pics taken yesterday. I think they look the Muts Nuts and very well made. Take no notice to the spring setting (the hex nut in the middle) as iv since wound it in alot so the valve closes at idle. Very easy to fit with a basic socket set and a pair of Water Pump plumbing Pliers to get the straps off the pipes. Be very carefull not to drop the nuts into the engine bay though. I put a cloth under it just in case.


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## ChuckUK (Jan 1, 2009)

With these in the fully recirc position or only about 20% vent, can you hear any difference ? Any vids ?


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## Gavinsan (May 28, 2012)

would love to hear what these are like , any london based gtr's running dump valves ?


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