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Borg Warner EFR Series Turbo's V 2.0

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Posted (edited)

you're overthinking it and your gut feel is way off. Its primarily an oil drainage concern. 

the axial thrust forces on a compressor/turbine assembly are huge when operating at high mass flows. force on the thrust surfaces due to gravity will be orders of magnitude less. the compressor its trying to suck itself out the front of the turbo and the turbine is trying to blow itself out the exhaust. yes, these forces are in opposite directions but do not cancel completely which is why journal bearing turbos require a thrust bearing as they have no inherent axial stability otherwise.

from your chart the most appropriate bearing for a CHRA would either be a pair of identical 7s or a pair of 6s in a mirrored arrangement.

main concern is oil drainage and oil pooling at the back of the CHRA if the angle is excessive, for the same reason a maximum of 20degrees of rotation about the shaft axis is recommended.

remember, accelerating and braking the car at ~1g is going to impart more force on the rotating assembly than inclining it by even 45 degrees, let alone 10 or 20.



this is a question that should be directed at BW.

Edited by burn4005
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