The Weistec W.3 Turbo Upgrade for the BMW 4.4L twin turbo N63B44O2 Engine found in the M550i, M750i and M850i vehicles provides vastly improved top end performance throughout the power band. Thanks to the high flow intake pipes and enlarged compressor cover inlet, response of the turbos is near stock while capable of flowing substantially more air than the factory turbos!
The factory turbocharges are disassembled and fully inspected. The compressor cover and center cartridge are then machined to accept Weistec's 5-axis CNC machined impeller wheel which despite being substantially larger, weighs the same as the factory cast impeller wheel. Externally, the compressor cover is modified to compensate for a much larger impeller wheel. The new impeller wheel supports greater power levels than the factory unit with little to no sacrifice in spool and response thanks to the high flow intake pipes and large compressor cover inlet. The turbochargers are then reassembled with new seals and bearings, then fully balanced for smooth operation and OEM service life. All the OEM oil and coolant lines bolt right up making for a simple install.
For maximum results, proper supporting upgrades and ECU tuning are required.