Crank Bearing material Options

[malcolm2]

WHat is the difference, or benefit of using Bronze (edit below) main bearings vs "steel backed".

I am building a daily driver, not a race car, so I am after long lasting, good quality.

EDIT... oops. I asked the vendor, they really don't know what the difference in material is. and it turns out BRZ in their description means Brazillian.

So they question may or not be about material, but it is still: "Is there a difference or benefit to BRZ bearings?"

THanks

[Superhawk996]

In theory steel backed bearings are supposed to help distribute the bearing load better and prevent some of the "pounding" that will elongage the main bearing bore on the case.

No so much a concern at stock HP levels.

With a big bore there are a lot of other incremental forces at work (increased RPM's, increased rod & piston inertias from big bore pistons, etc.) and I'm not sure that steel backed would really help under those conditions.

[Mark Henry]

Only steel backed babbitt coated are available as far as I know for our engines . The bearing center main are steel, copper alloy and then lead alloy babbitt coatings.
For a while early 2010- during the bearing shortage, there was aluminum backed center mains, don't use them.

Bearings are soft babbitt for a reason, it's considered a sacrificial surface. FOD will to a point sink into the surface and if metal to metal happens hopefully the crank journal won't be damaged.
Cranks have to run on dissimilar metals, one hard (crank or cam) and the other a softer metal. This prevents galling if low oil pressure happens.
Cams run at only half the speed of the crank, The T4 has bearings, but engines like the 996 the cams run right on the alunimum casting.