[fasteddie222]

FIXED: Read this guys

This is quoted from rob@rbturbos.com:

RB Turbo N55 OEM Turbocharger information>>>> - 01-31-2012, 10:34 PM
Ok so I finally got the N55 Turbo and had a chance to take a close look at it via a teardown.

First off, there have been questions about whether it will work on the N54 or vice versa. The answer to that is yes it could, but not easily. The N54 Twin Turbos have all of the same mounting locations on the top of the flange, but not on the bottom. Due to manifold design and packaging constraints the flanges are secured via studs from the heads at points at which they can be reached for installation and removal jobs. The N54 Twins have studs on the bottom side of the flange that can not be utilized with the N55 Single. What this means is that in order to place the N55 Turbo on the N54 you must remove 5 of the N54 Studs, and redrill the head and add 4 studs in the correct location to properly secure the N55 Turbo. Pending on the casting of the N55 head and if it has provisions for the N54 stud placement (doubtful yet possible), you maybe able to bolt up N54 Twins to the N55 engine. Aside for this mounting fiasco, it does seem doable (at least on the surface).

Secondly, the N55 Turbo is pretty cool. It does use a custom version of the smallest Borg Warner EFR Billet Compressor wheel (62mm). However it has a custom inducer sizing, which is quite abit smaller than the exact wheel that is used in the BW EFR 62mm (45.8mm vs. the EFR's 49.6mm) with the extended tip technology. It also uses the twin seal arrangement as do the EFRs (not sure if this is common across other BW units). The turbine has the backing plate like the EFRs as well, but I do not think its a Ti wheel. The turbine is also quite small, approx. 53mm Inducer and 46.1mm Exducer. It is a Journal Bearing Turbo, unlike the EFR. Both housings seem to be built on the EFR foundation. Overall it seems like a very nice unit OEM unit, just does not have much flow potential.

Thirdly, upgrading the unit. BMW has DONE it again. I know some of you are going to say, lop of the turbo, toss on a flange or just weld up another turbo. The problem is that it is NEVER that easy. In this case the original twin scroll manifold has a BMW specific turbine housing inlet that would not adapt to any of the standard available BW twin scroll offerings (ie. based on the T4 flange). It would take some transitional adaptive flanges to be able to even consider such a thing, which is probably another long stretch considering all of the consequences of lowering the turbocharger that much (requiring pretty much all things replaced aside for the exhaust manifold). The compressor housing has plenty of material to upgrade the wheel, there is no issue there when it comes to upgrading. However the turbine housing doesn't seem to have too much to work with and modifying it is fairly complex considering it is twin scroll (the new wheel will have to still retain certain original specs and has to be chosen wisely) and it will be a handful trying to tool into a milling process. If the original turbine can not be upgraded there will be little that can be done short of tossing a larger (potentially mismatched) compressor wheel on the original turbine shaft and hoping for some fair gains. I haven't given up on it, need to do some homework on turbines to see what meets my needs (if anything); but not looking too great on the surface.

Lopping off the turbo is also not out of the question, but doing so and matching the inlet style will be necessary to have even the slightest chance of success. I need to look further into this as well, but I am not holding my breath.

Rob

See www.rbturbo.com for N54 Twin Turbo Bolt-On upgrades, or contact directly 314-630-8950 rob.rbturbo@gmail.com for a price quote.

Rob@RBTurbo
Demigod

Posts: 1,563
Join Date: Feb 2009
Location: Midwest USA
Car: 335I

Today, 09:28 AM
Just purchased a few N55 singles to butcher up...

Little update here from rob for those of you that don't follow n54tech.com

Rob@RBTurbo
Demigod

Posts: 1,606
Join Date: Feb 2009
Location: Midwest USA
Car: 335I
Yesterday, 10:38 AM
I've decided to NOT go with the simpler upgrade I was anticipating for month end. That said I am going to (attempt) to do a more thorough job and come up with something VERY remarkable for the N55 crowd. It will cost more to build but I don't think anyone will be complaining if all goes to plan. Will know more when parts are in my hands shortly. I'm actually more excited about this than ever

Another update 1/24/2013

Originally Posted by Rob@RBTurbo
Ordering donor parts today. Get excited but also keep your fingers crossed!

In the meantime, can someone post some pics of how the turbo sits in the car? I am most interested in seeing how the compressor housing is plumbed (inlet and outlet). This will help me get a quick scope of some extras I may need to produce.

BTW, if I can pull this off, I fully expect about 100hp (crank) gains and a sub $3k price tag. It is a single turbo but the donor parts are very cutting edge and hence big $$$.

Thanks,
Rob

[reirei725]

That's pretty old lol. But he did just buy some N55 turbos to work on starting January.

[Abear]

Breaking news from almost a year ago.

Whats better is the post that he made today stating he just bought a few N55 turbos to chop up.

[fasteddie222]

Sorry I tried to quote the whole thread that he bought the turbos. I am on my phone so wasn't able to quote everything.... Sorry haha but it's a very interesting thread on that forum.

[bulldog_yyc]

welcome to 2012

[fasteddie222]

Now that I am on my computer I fixed the first post and I put what I intended to put in the beginning. I wanted to add the january 2012 posting for the people that don't know what is going on and the posting rob just added today that he just purchased n55 turbos which is great news for us.

[Suds]

You always wanted a hood bludge, like on a mustang, right?

[benzy89]

Tony/Vargas Turbos has already found a local N55 to start working on. The project date for the R&D to begin is right after the new year


Be interesting to see who comes out with a solid aftermarket turbo option for the N55 first

[fasteddie222]

I don't know why but I have that feeling that the n55 is going to be a beast with upgraded turbos

[benzy89]

Originally Posted by fasteddie222

I don't know why but I have that feeling that the n55 is going to be a beast with upgraded turbos

I've got a feeling that the N55 internals are gonna give up before it hits N54 power levels, especially now with the new Vargas Turbos coming out.

[eyim1988]

Originally Posted by benzy89

I've got a feeling that the N55 internals are gonna give up before it hits N54 power levels, especially now with the new Vargas Turbos coming out.

+1. I havea feeling 500 whp/500 torque will be near its limit.

[Hoody335]

Originally Posted by eyim1988

+1. I havea feeling 500 whp/500 torque will be near its limit.

Why do you feel that way? I have a feeling that it will out work the n54

[benzy89]

Originally Posted by Hoody335

Why do you feel that way? I have a feeling that it will out work the n54

Cast internals / Cheaper components (the N54 was discontinued because it was significantly more expensive to produce than the N55)

[Hoody335]

Originally Posted by benzy89

Cast internals / Cheaper components (the N54 was discontinued because it was significantly more expensive to produce than the N55)

It was also less reliable

[eyim1988]

This.

But the same can be said about the later year n54's.

[benzy89]

Originally Posted by eyim1988

This.

But the same can be said about the later year n54's.

Tru... The 07-08s are bullet proof. The 09-10s dropped the forged internals in place of cast components to try & cut costs. N54 was still more expensive, so BMW made the full switch to the N55.

The N54 is def a rock solid platform for higher performance, illustrated that it's still used in the 1M & 335is. Anyone who argues that BMW just used these engines because they had them lying around is an idiot, because BMW only builds cars to order (a small amount of generic/popular models for dealers & then customer specific orders) so there were never warehouses with N54s just lying around.

[E90Company]

Originally Posted by benzy89

Tru... The 07-08s are bullet proof. The 09-10s dropped the forged internals in place of cast components to try & cut costs. N54 was still more expensive, so BMW made the full switch to the N55.

The N54 is def a rock solid platform for higher performance, illustrated that it's still used in the 1M & 335is. Anyone who argues that BMW just used these engines because they had them lying around is an idiot, because BMW only builds cars to order (a small amount of generic/popular models for dealers & then customer specific orders) so there were never warehouses with N54s just lying around.

Does my car have forged internals? 2008 build date May?

[benzy89]

Originally Posted by E90Company

Does my car have forged internals? 2008 build date May?

It should, they switched to cast pistons for the N54 12/2009

[melloww22]

Originally Posted by benzy89

It should, they switched to cast pistons for the N54 12/2009

Concur

[reirei725]

[fasteddie222]

Well I think that we can't come to a conclusion until the turbo upgrade is made

[F335i]

OMG N54 vs N55 all over again. Only time will tell which one is more powerful and efficient, all I know is that N55 is more reliable, N54 is always getting work done.