Downpipes from Longlife

[Jon441cc]

i will give Competition Fabrications a ring sometime next week, and
try to take the Avant down there so he can see what sort of work it will entail.

i'll keep you posted

[Keeper of The Kitten]

Sounds like a champion idea, I think you'll be impressed by his workmanship - if not the state of his workshop, which by all accounts can get a little cluttered! Fear not, though - his work area is organised chaos, from which things of great beauty will spring forth!!

__MDC__

[robo]

there you go

with airbox in

[robo]

With no airbox

[Jon441cc]

Looks very neat and tidy. Do you have a sport cat on your avant or just 2 boxes as i was told by my local MOT place that my avant did not need the cats to pass its MOT and right now i only have 2 boxes, and the drone from the exhaust at 2500 to 3000 is really bugging me, when i drive past people they cant believe the sound is coming from the avant and i find myself trying to sit lower in my seat so no one can see me

[robo]

Looks very neat and tidy. Do you have a sport cat on your avant or just 2 boxes as i was told by my local MOT place that my avant did not need the cats to pass its MOT and right now i only have 2 boxes, and the drone from the exhaust at 2500 to 3000 is really bugging me, when i drive past people they cant believe the sound is coming from the avant and i find myself trying to sit lower in my seat so no one can see me

I have no cats just two boxes.

You shoud get seperate WG pipe done then you can say something about avant been loud

[Jon441cc]

An Avant! with a seperate wastegate pipe what must people think when they hear that thing go past at speed

[maRS2]

Keeper the kitten: In a exhaust flow the faster stream is center one as the outer is slowing due to friction against stainless so going to 2 time 2.5" is going to increase a lot that friction area and also you will slow the fast center stream at the split.
You should also take in consideration that the hoter the faster the gaz flow is so by making 2 tube you will again incease the cooling area.

Those are the reason why turbo car always have single tube as we want to realese those gaz as fast as possible.

[Keeper of The Kitten]

maRS2, I agree with you there, the "laminar" gas flow would be slower near to the tube walls, but what is the point inside the pipe where it becomes a fast stream? If we had 2 x 3" pipes it would inevitably be more free flowing than 1 x 3" pipe, so I wonder if 2 x 2.5" would still be better flow than 1 x 3"?

But I see what you mean about the place where the pipe is splitting into 2 pipes, thanks for making me aware of that!

For hotter faster flowing gases, maybe lagging (insulating) the pipes would help?

I would be happy to know the answer if you can help me! I want to run with the exhaust system to the tail but not going over the rear suspension, I want the minimum restriction, so perhaps it is better to use 1 x 3" under the rear differential?

I am willing to listen to any advice on this issue!

__MDC__

[Ross]

Update!!

Hi Jon,

Any luck with this fabricator?

I've finally heard back from Longlife - spoke to Ian in Bristol, who wants to meet and have the car as a 'guinea pig'. We're going to plan it for probably 3rd week of March. Unfortunately, the only jig they can find is for 2.5" so it'll involve making a new one.

My only issue is my external wastegate pipe might make it a bit harder to use my car as a guinea pig, so if anyone else is in teh Bristol area with a complete stock Downpipe and a bit of moola, and woudn't mind putting a day to R&D for a supply of 3" S/S downpipes then please let me know!! Obviously, this would help keep the cost to a sensible level as well.

Marco, come out of retirement!!

[rotoryboy]

Marco, come out of retirement!!

Or if someone has a Marco downpipe (off the car) you could use as a template

[Jamo]

maRS2, I agree with you there, the "laminar" gas flow would be slower near to the tube walls, but what is the point inside the pipe where it becomes a fast stream? If we had 2 x 3" pipes it would inevitably be more free flowing than 1 x 3" pipe, so I wonder if 2 x 2.5" would still be better flow than 1 x 3"?

But I see what you mean about the place where the pipe is splitting into 2 pipes, thanks for making me aware of that!

For hotter faster flowing gases, maybe lagging (insulating) the pipes would help?

I would be happy to know the answer if you can help me! I want to run with the exhaust system to the tail but not going over the rear suspension, I want the minimum restriction, so perhaps it is better to use 1 x 3" under the rear differential?

I am willing to listen to any advice on this issue!

__MDC__

Yes but with two pipes not matter the size you need a y pipe section which slows gas down as it causes turbulence at the split

It's no coincidence that all single 3" exhausts systems outperform the stock twin 2.5 section.

Also bigger is not always better with exhausts, the larger the diameter the exhaust the cooler the gas will become reducing flow speed. It's a trade of which size you should run vs bhp output.

[Jamo]

Or if someone has a Marco downpipe (off the car) you could use as a template

Heh probably all on the car now (also weren't the Marco pipes 70mm which is 2.75" the same as an RS2 downpipe?)

Can't they use a standard downpipe as a template?

[Ross]

Heh probably all on the car now (also weren't the Marco pipes 70mm which is 2.75" the same as an RS2 downpipe?)

Can't they use a standard downpipe as a template?

Yeah, they use a regular downpipe, make a jig using it as a template (except for a 3" pipe) and then use that for any future fabrications. That's why Im taking the car down for the day; but I think it would be helpful to have someone else there as they need to then test the jig and make a 2nd 3" downpipe. Would make sense for 2 of us to go down there, and make it affordable too.

Cheers
Ross

[Jamo]

Yeah, they use a regular downpipe, make a jig using it as a template (except for a 3" pipe) and then use that for any future fabrications. That's why Im taking the car down for the day; but I think it would be helpful to have someone else there as they need to then test the jig and make a 2nd 3" downpipe. Would make sense for 2 of us to go down there, and make it affordable too.

Cheers
Ross

Should have asked Sal for a downpipe last week mate!