Quote:
Originally Posted by sahyoun
I don't think the n55 is much cheaper of it even is cheaper. Yeah it has one less turbo but it's a Borgewarner twin scroll ball bearing which I can promise is a lot more than two td03's not to mention the n55 head is much more to produce considering it has valvetronic and the n54 does not. The n55 may be cheaper but if also gets torque much sooner and has lower emissions which is all BMW cares about
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AFAIK, the N55 turbo uses journal bearings, not ball bearings.
EDIT: Excerpt from posting by Rob Beck:
"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."
Neil