Exhaust Bypass / Diverter Valves (Non BCS)

[TheWeeman]

So I have been looking into exhaust bypass valves or 'Cutout Pipes' as they are also known.

This is basically the same thing as BCS use in their exhausts (They call it a power valve). For those of you who don't know, this is a valve placed somewhere on the exhaust system that can be opened via a remote and gives you the option of noise and flow when you want it and then can be closed in situations when loud exhaust noise isn't really appropriate. The advantage also being that you can control the volume of the exhaust by placing it at different points in your system, or some kits give the option to partially open the valve.

The first type is electric and then the second type is controlled by boost (BCS type). These are now installed on alot of new performance vehicles like the TTRS, they are used alot in the states and get rave reviews, however i'm lead to believe electric controlled ones aren't too reliable as the motors often fail. More primitive versions have been used on american muscle cars since the 60s!

I'm looking at having one installed on the S3 as I don't think my neighbours will appreciate me starting a full system at 5am!

So... who is running them? Do you use an electric one or a boost controlled one? (Turbo only). How does it affect your map etc?? which do you use? What are your opinions?

Here is a little info and and a few examples:

Electric: (cheaper are available)
http://www.ratsport.com/PBSCProduct.asp?ItmID=9611815

Boost Controlled: (hook up a vac pipe)
http://www.spracingonline.com/spblog/?p=131

 

[smurfworth]

Id go for the vac one because even the standard s3 exhaust has a valve to allow extra flow when on boost.

BCS have a vac valve because they don't want to potentially harm the turbo if the user doesn't have the valve open when on full boost which will basically strangle the turbo.

There's more to it than just for noise purposes, even on the standard system.

 

[TheWeeman]

Id go for the vac one because even the standard s3 exhaust has a valve to allow extra flow when on boost.

BCS have a vac valve because they don't want to potentially harm the turbo if the user doesn't have the valve open when on full boost which will basically strangle the turbo.

There's more to it than just for noise purposes, even on the standard system.

Me too, the vac version looks like the one to go for.

Ah I see, also great for performance surely on a forced induction car I reckon.

 

[smurfworth]

Me too, the vac version looks like the one to go for.

Ah I see, also great for performance surely on a forced induction car I reckon.

R tech have seen an increase of 10hp over other performance exhaust systems when testing the BCS so it's definitely great for performance.

 

[TheWeeman]

R tech have seen an increase of 10hp over other performance exhaust systems when testing the BCS so it's definitely great for performance.

That's impressive. I've been looking at a few other forums and it seems they are getting similar results. Hard to find the kits in this country though, I may have to import it.

 

[audismart]

Has to be the vac one, I was looking at getting a BCS powervalve and this give buyers another option of different exhaust systems.

 

[desertstorm]

I fitted a valve to my 3.0 TDI about 16 months ago, Mine is operated by a remote, it offers a small increase in power but mainly it's there to turn the volume of the exhaust up and down.
http://www.audi-sport.net/xf/threads/karls-3-0-tdi-build-thread.204785/page-4#post-2179626

It's very similar to that one linked to earlier, indeed that looks like a Chinese made part with a sticker on it and a £200 price hike. They are available in various sizes, I used a 2.5 inch on my car.
These are 3 inch ones first one is operated on a switch,

http://www.aliexpress.com/item/3-El...est=201556_8,201527_3_71_72_73_74_75,201409_5

Second one on a remote,
http://www.aliexpress.com/item/3-El...est=201556_8,201527_3_71_72_73_74_75,201409_5

I have bought loads of stuff from Ali Express and never had an issue. Just takes a few weeks to come sometimes.

Don't bother buying this type of cutout with the actuator like this, they are no good.

http://www.aliexpress.com/item/3-St...est=201556_8,201527_3_71_72_73_74_75,201409_5

Karl.

 

[TheWeeman]

Thanks Carl, I was looking at the ali express stuff.

I'll check out the electronic stuff in the link but I really had my heart set on the boost controlled valve. However for 60 odd dollars it's worth that for a stainless Y pipe alone

 

[leshkin]

That boost actuated valve looks like good value! Not as compact or tidy as the BCS unit, but can't really complain about the value for money aspect.

One other item that differentiates the BCS system is the flexible sleeve on the downpipe. BCS one is much longer than the length of the other aftermarket systems and is much less prone to splitting or causing rattling noises after a while. This is according to Nige at BCS.. I have no clue about this, but sounds like it's worth considering when upgrading.

 

[TheWeeman]

Leshkin - Good value indeed.

I'm going to go for this boost actuated one:
http://m.aliexpress.com/item/32299130835.html

Around £50 all in, then I'll source a Y piece and vac pipe myself. Should be onto a winner