VR6 Turbo Downpipe 2.5" or 3"

[emu 0]

Getting bored again so had some thoughts about putting a turbo to my VR6. Just need my hands getting dirty again :)

 

Thing is that I have a brand new spare Holset HX35 sitting in a box. The outlet is a 2.5 v-band style. My exhaust is 2.25" or 2.5" stainless steel and I'm not planing to change it.

 

Looks like a downpipe will be custom made by myself and I can use a 2.5" V-Band TO 3" V-Band adapter and plug it in between turbo and dwonpipe.

 

Is it just worth going from 2.5 to 3 and then back to (2,25-2.5) exhaust.

 

What would be pros and cons between going 2,5" all the way and putting 3" downpipe and leaving everything else at 2.5" ??

[VAG-hag 0]

If the outlet is 2.5 I can't see how a bit of 3" could benefit flow?

[dragon green 4]

It wouldn't benefit at all,exhaust gases pulse, going to 3" then back to 2.5" would hit power !

What system have you got at the moment ?

Most performance systems are 2.25"

[emu 0]

It wouldn't benefit at all,exhaust gases pulse, going to 3" then back to 2.5" would hit power !

What system have you got at the moment ?

Most performance systems are 2.25"

 

I think its Miltek 2.25" and I was thinking about making 2.5" downpipe with a reductor at the end to fit the exhaust at 2.25" but after doing some research found that everybody are fitting 3" downpipe in VRT so thought it is worth asking the question if its worth going from 2.5" to 3" downpipe to 2.25" exhaust as it make no sense to me.

 

If I had a 3" turbo outlet I'd go for 3" downpipe.

 

Having 2.5" turbo outlet my understanding is that I should go for 2.5" downpipe.

[dragon green 4]

That's what I would do

[VAG-hag 0]

 

If I had a 3" turbo outlet I'd go for 3" downpipe.

 

Having 2.5" turbo outlet my understanding is that I should go for 2.5" downpipe.

 

Sounds right :)

[madmatt 10]

minimum 2.5" system but going bigger will help reduce back pressure and help the turbo spin up faster and reduce egt.

[Kevin Bacon 5]

Doesn't matter what you do with the exhaust at the

 

Having said that, I've seen small Holsets on train engines that have small outlets which expand into at least a 4" diameter system.

 

Keep in mind Holsets are cheap diesel engine turbos built for mega miles, so they're tough, but may not give the spool characteristics you're looking for.

[emu 0]

 

Keep in mind Holsets are cheap diesel engine turbos built for mega miles, so they're tough, but may not give the spool characteristics you're looking for.

 

Yep, good point and I know about it so the one I've got is a custom built quick spool turbo with 12cm housing instead typical 16cm.

[Jim Bowen 1]

What is the standard diameter on a VR6? Only ask as this thread made me check the techtonics one i bought and that says its 2" Mine is going on a NA VR6 and they did mention it was bigger than standard.

 

http://techtonicstuning.com/main/index.php?main_page=product_info&cPath=2_13_60_136&products_id=187&zenid=0uhce17dpq7h5c50bq1kcv1c67

[seanl82 23]

Standard exhaust diameter for vr6 is 2 1/4" Jim. I would have thought the techtonics one is this at a minimum......,

[coullstar 0]

That's a 2in dual downpipe though, you need to measure the collector ID. Std size is 2.25in for the actual system.

[madmatt 10]

techtronic twin 2" down pipe to a 2.5" system for the vr6.

[dragon green 4]

Magnex system is 2.25"

My down pipe is 2.5" and mines "only" a 1.8T

[Kevin Bacon 5]

The downpipe diameter on the VR6 is quite small from memory, and I would stick to it personally. The torque usually suffers if you up the DP size. The Techtonics 2.5" dual borla system is bloody brilliant though. Ground sound and quality.

[Jim Bowen 1]

I nearly ordered that at same time as the downpipe. But sticking with the magnex for now.

 

Quite interested to see what power I get before changing too much. Still considering the full tt exhaust with a sports cat. But will leave it. Would be nice to get a before and after figure with some mods.