N2 4age main and rod bearing clearance's

[slideways]

Does anyone have the N2 bearing clearance specs for the 42mm crank?

FOUND!!

Why do N2 and FA engines run looser clearances?

[slideways]

Courtesy of Jrad,

The TRD bible says,

Main bearing clearance: 0.05 - 0.065 mm

Crank pin bearing clearance: 0.04 - 0.06 mm


And from what I can gather, please confirm these specs if you can;

Ae86 workshop manual,

Main bearing oil clearnace: 0.015 - 0.033 mm Limit: 0.10 mm

Crank pin bearing oil clearance: 0.020 - 0.051 mm Limit: 0.08 mm


So could anyone elaborate as to why TRD have gone to looser bearing clearances? For the research I have done, it indicates that tighter tolerances seem more suited to high rev race type applications.

[Big T]

Dry sumps. Allows more reliable and consistent oil supply at generally higher pressure.


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[slideways]

Dry sumps. Allows more reliable and consistent oil supply at generally higher pressure.


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So other than the "because they can",
what are the advantages of running a greater clearance?

[Big T]

It's probably due to the rpm they run them at. Larger tolerances allow for slight flex in the crank, particularly at tdc where the piston changes direction. Even a perfectly machined crank/block will flex a touch at 10k+ rpm.


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