[echangf30]

does anyone know where the f30 335 turbo is made by? I heard garrett. and I heard the turbine is all billet too!!! anyone else?

[Eric SS]

Borg Warner

Originally Posted by Rob@RBTurbo

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

[echangf30]

that's good to know..... thanks man.