Downpipes... how big is too big?

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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RS2
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Downpipes... how big is too big?

Post by RS2 » Mon Jul 10, 2017 3:16 pm

Sooooo a few of you will have seen that I'm sticking a BCY lump into my VW Camper :biggrin3:

The upside of this is that I can do anything I want with the exhausts, it's a 1989 van so it doesn't need cats.

The downside is that the engine is at the back so I don't have tons of room for lots of silencers to keep the noise at a sensible level.. it is going to a street van with 7 seats and occasional weekends away etc.

How big is too big on the exhaust? I've seen some very nice 3" downpipes from KWE which are 3" etc (see link below) but I won't be buying as they're expensive and I'll be changing the direction of exhaust to face the opposite direction.

http://www.kwe-racing.de/Audi/Audi-S6/R ... ::781.html

I'm already considering upping the turbos a little in spec but more than 550bhp is a bit pointless in a van surely? :FIREdevil:

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Re: Downpipes... how big is too big?

Post by Shoppinit » Mon Jul 10, 2017 3:20 pm

The hotsides are what most restrict the power in the RS6 engine to 530-550, so if you can go big manifolds and DPs then you'll be able to liberate mucho horses. I think 700hp in that van should make it a fairly amusing drive?
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Re: Downpipes... how big is too big?

Post by RS2 » Mon Jul 10, 2017 3:53 pm

Shoppinit wrote: ↑
Mon Jul 10, 2017 3:20 pm
 The hotsides are what most restrict the power in the RS6 engine to 530-550, so if you can go big manifolds and DPs then you'll be able to liberate mucho horses. I think 700hp in that van should make it a fairly amusing drive?
Lol, amusing would be one word for it. Undrive-able would be another ;)

Is 3" big enough for the future and possible hikes up to those figures?

Just out of interest... how big is the stock downpipe if I was to use the primary cat outer as a size to go off? Cutting the pipes here would give me the top sections and a nice diameter to go from...

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Re: Downpipes... how big is too big?

Post by bam_bam » Mon Jul 10, 2017 4:05 pm

3" DPs CATless will serve you well up to 550, maybe a tad more. Ben is right, the manifold might free up more.
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Re: Downpipes... how big is too big?

Post by kvxxy » Mon Jul 10, 2017 10:31 pm

Does anyone sell manifolds off the shelf or is a custom only job?
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Re: Downpipes... how big is too big?

Post by bam_bam » Mon Jul 10, 2017 10:39 pm

Custom AFAIK. What's wrong with 550?
Check the Ultima forums, a couple of those guys have used BCY/BRV and made custom zoorsts.
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Re: Downpipes... how big is too big?

Post by Shoppinit » Mon Jul 10, 2017 10:48 pm

Might still be for sale.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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Re: Downpipes... how big is too big?

Post by kvxxy » Mon Jul 10, 2017 11:21 pm

bam_bam wrote: ↑
Mon Jul 10, 2017 10:39 pm
 Custom AFAIK. What's wrong with 550?
Check the Ultima forums, a couple of those guys have used BCY/BRV and made custom zoorsts.
Shoulda bought my old car, it'd have everything you need right now...
Nothing at all. It'd be interesting to see what sort of power these cars can make. 700bhp in that van would be insane!
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Re: Downpipes... how big is too big?

Post by RS2 » Tue Jul 11, 2017 4:55 pm

Anyone got a video of an RS6 running 3" downpipes, system but with silencers?

I need this van to be sensible to be driven everyday but 3" from throughout from the turbos sounds good.

On my project, I don't have to have a bend straight after the turbo flange, there's nothing in the way there...

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Re: Downpipes... how big is too big?

Post by bam_bam » Tue Jul 11, 2017 5:46 pm

I used to have a video but cumbucket pulled a dickmove.
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Re: Downpipes... how big is too big?

Post by Shoppinit » Tue Jul 11, 2017 5:47 pm

Phuck fotobucket.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
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