N55 Downpipes

[bryans2k]

Anyone making downpipes yet? It's an extremely easy job now with the single turbo.

[ar design]

Someone needs to get us an N55 to test fit on - there is a FREE set of downpipes involved, and possibly more

[MarkR171]

Originally Posted by ar design

Someone needs to get us an N55 to test fit on - there is a FREE set of downpipes involved, and possibly more

Why can't there be any companies based in Hawaii?

[ZIPNBYE]

So, as it's just one turbo, wouldn't be just a downpipe?

[ar design]

Originally Posted by ZIPNBYE

So, as it's just one turbo, wouldn't be just a downpipe?

Correct, good catch

[bimmerboy]

+1. one turbo=one downpipe. should bring downpipe prices down to the $3-400 range for N55 owners.

[Jonny550]

i think it should be pretty simple. I figures AR would have something going already. From what it seems like their are twice as many sensores on the new n55 then on n54 witch i would guess complicates things. And yes we will probably be seeing the most high end pipe going for no more the $300

[Future M1 owner]

Originally Posted by maxnix

Thought there was a pipe for each scroll? Well, I guess it is siamesed at the turbos, but still two distinct paths.

No. A twinscroll turbo has a single turbine outlet ,just like any other turbo. (Pic shows a turbine housing for an external wastegate setup)

Edited to add: Below is a pic of an internally wastegated (as on the N55) twinscroll turbo.

[MikeNeo]

Originally Posted by ar design

Someone needs to get us an N55 to test fit on - there is a FREE set of downpipes involved, and possibly more

If you were closer to ny...

[ZIPNBYE]

Originally Posted by maxnix

Thought there was a pipe for each scroll? Well, I guess it is siamesed at the turbos, but still two distinct paths.

You do understand how a turbo works, right?

One exhaust impeller, one intake impeller. Exhaust in (via exhaust manifold aka header), exhaust out (via downpipe). Intake in (via intake system), intake out (via intake piping, usually to intercooler).

One turbo, one downpipe.

[Mad Maxx]

For a "Twin Scroll" Turbo, there should be 2 Cold Side Air Inlets, 1 Main Hot Air Out (Both Compressor Wheels Combined), and 1 Main Exhaust Out (Both Compressor Wheels Combined).

But it Looks like the Turbo on the N55 is not Sequential, so there will only be 1 Cold Air In, 1 Hot Air Out, and 1 Exhaust Out. So...1 Air Intake, 1 Charge Pipe, 1 Downpipe.

[Future M1 owner]

Originally Posted by Mad Maxx

For a "Twin Scroll" Turbo, there should be 2 Cold Side Air Inlets, 1 Main Hot Air Out (Both Compressor Wheels Combined), and 1 Main Exhaust Out (Both Compressor Wheels Combined).

But it Looks like the Turbo on the N55 is not Sequential, so there will only be 1 Cold Air In, 1 Hot Air Out, and 1 Exhaust Out. So...1 Air Intake, 1 Charge Pipe, 1 Downpipe.

No sir, wrong also.
Twin scroll is nothing more, and nothing less, than a divided exhaustmanifold connection on to the turbine inletside (see the pics above).
There is one compressor wheel, as there's one turbo.
There is one turbine wheel, as there's one turbo.

And a single turbo cannot be sequential..(in sequence with what?)

Edited to add: I think you may have got mixed up with the compound turbo setup found on perfomance diesels, where one turbo actually "blows through" another, in order to achieve the boost levels required by these engines (35-45+psi) .

[Mad Maxx]

Originally Posted by Future M1 owner

No sir, wrong also.
Twin scroll is nothing more, and nothing less, than a divided exhaustmanifold connection on to the turbine inletside (see the pics above).
There is one compressor wheel, as there's one turbo.
There is one turbine wheel, as there's one turbo.

And a single turbo cannot be sequential..(in sequence with what?)

Edited to add: I think you may have got mixed up with the compound turbo setup found on perfomance diesels, where one turbo actually "blows through" another, in order to achieve the boost levels required by these engines (35-45+psi) .

No....you're Wrong.

I do come from a Performance Background, it's what I do all Day every Day.

...and Yes, Twin Scroll Technology is now being Used on Diesels, like the New Scorpion Motor in the Fords...Here's how it Works:

The 6.7L uses a Garrett single sequential turbo (SST) with variable geometry, a dual-scroll exhaust housing, and an externally actuated wastegate. This turbo has a pair of compressor wheels that are coupled together on a single shaft driven by the turbine wheel. The design is said to dramatically increase the compressor map's range and functions like a sequential twin-turbo system. The boost pressure will be around 30 psi, the turbine shaft speed will see up to 130,000 rpm, and the whole system was designed to function as an exhaust brake. The compressed air will be cooled by an air-to-water intercooler-another first in this segment.

[ZIPNBYE]

...and bringing things back down to earth...that's not what BMW is using on the N55. It's just one turbo, with one exhaust and one intake impeller running in combination on one shaft.

[TreDirtyFive]

A single doesn't necessarily mean cheaper. Perhaps if it's catless. But it's easy to use, say, a 200 cell HJS cat and propel the DP to 800+ prices.

[Future M1 owner]

Originally Posted by Mad Maxx

No....you're Wrong.

I do come from a Performance Background, it's what I do all Day every Day.

...and Yes, Twin Scroll Technology is now being Used on Diesels, like the New Scorpion Motor in the Fords...Here's how it Works:

The 6.7L uses a Garrett single sequential turbo (SST) with variable geometry, a dual-scroll exhaust housing, and an externally actuated wastegate. This turbo has a pair of compressor wheels that are coupled together on a single shaft driven by the turbine wheel. The design is said to dramatically increase the compressor map's range and functions like a sequential twin-turbo system. The boost pressure will be around 30 psi, the turbine shaft speed will see up to 130,000 rpm, and the whole system was designed to function as an exhaust brake. The compressed air will be cooled by an air-to-water intercooler-another first in this segment.

With all due respect, how does this, and your discription of "twin-scroll" in your previous post, tie-in with either the N54 or the N55 engines, again?

[TreDirtyFive]

Originally Posted by Future M1 owner

With all due respect, how does this, and your discription of "twin-scroll" in your previous post, tie-in with either the N54 or the N55 engines, again?

+1

[Mad Maxx]

Originally Posted by Future M1 owner

With all due respect, how does this, and your discription of "twin-scroll" in your previous post, tie-in with either the N54 or the N55 engines, again?

The same way your Picture of a Turbo Kit for an Evo X Ties in.

[bryans2k]

Why dont y'all keep to the topic.

[JHZR2]

So back to topic, what I understand and seem to be seeing from the pictures is that there is a single exhaust connection, and two compressor outlets...

So there is one exhaust side wheel, and two compressors on one shaft and somehow segregated in the turbo body.

And so the benefit comes from the fact that you have all of the exhaust flowing through a wheel with high rotational inertia, and two smaller wheels with geometry such that the torque required is lower, so inertia is lower - faster spool, better response, at least in theory...

Is that close?

[perral1]

Originally Posted by JHZR2

So back to topic

You realize that the topic was about downpipes...err, a downpipe...for the N55, right?

[Future M1 owner]

Originally Posted by Mad Maxx

The same way your Picture of a Turbo Kit for an Evo X Ties in.

Sir, I will make only one additional comment here, not to prolong this tennismatch with you, but only because it's clear from certain posts that there's a need for some insight on the very basic workings of turbos, and this thread is only prolonging the supply of confusion and misinformation.

-You wrote: For a "Twin Scroll" Turbo, there should be 2 Cold Side Air Inlets, 1 Main Hot Air Out (Both Compressor Wheels Combined), and 1 Main Exhaust Out (Both Compressor Wheels Combined).

-This is (still) very wrong. I will state again that the term "Twin Scroll" only refers to the divided exhaust inlet to the turbine housing. It has no reference to anything on the compressor side, and whether the turbo has one, two, or 18 compressor wheels.

-Yes, even the Twin scroll SST you referenced, has two exhaust inlets on a single turbine, with a single turbine outlet. Twin Scroll to a t, exactly as explained above.

Therefore, even this complex, "Twin Scroll", multicompressor, variable vane baby has, drumroll, a single downpipe.

Which brings us nicely back to the N55, and, more importantly, to the topic of N55 downpipes.

The N55 has one turbo, therefore one turbinewheel, albeit with a divided turbine inlet, hence the twinscroll moniker, and therefore it has one downpipe.
Oh, and I almost forgot: It has a very conventional compressorhousing with, rather disappointingly for some, one single compressorwheel.