BMW S54 Rod Bearing Oil Pressures

[Cujet]

It is not true that track driven cars do not suffer from the problem. They do. Also, it's not due to low RPM use. It's due to high RPM inertial loads on the rods and rod bearings. The very high RPM's these engines turn places incredible stress on both the connecting rods and rod bearings. The loads far exceed the type of loads a rod and it's bearing might experience from, say, a turbocharged engine turning lower RPM and making more HP.

Those that dig deeper into this problem are also finding connecting rod stretch and bearing bore distortion.

I don't believe oil will fix the problem, although tougher bearings will help. The solution to the problem very likely includes lower reciprocating mass. Manufacturers that build successful high RPM engines universally use very light pistons. Even a seemingly minor reciprocating mass savings yields large improvements.

An example of a light weight piston:

It's unfortunate, but the proper course of action includes changing rod bearings before they wear out.

 

[Shannow]

Originally Posted By: SlipperySimon
Let me rather give my question a bit more direction...

1. I can't find the HTHS values of the 50WT and am wondering if they're higher than the standard 15W50?

2. Furthermore would there be any differences in the base stocks between the two products?

3. I'm sure that the racing oil will have to be replaced more frequently, but why is this?


HTHS is likely the same(ish) the Race has a lower VI, and slightly lower KV40/KV100, so siwngs and roundabouts about the same.

The street probably has SOME VII in it...can't get 160 VI on basestock alone that thick (I beleive).

NOACKs the same.

The Race has a dodgy CCS number, it's probably "recommended" for 15W than actually does it.

The race oils typically have less detergent/dispersent, so have less gunge holding capacity leading to shorter OCIs.

 

[Trav]

Just for the sake of comparison my Honda CBR 1100cc bike engine made 98 psi at warm idle and over 130 psi off idle with a red line of 11800 rpm, not far of 10 psi per 1000 it is also high flow, it would seem the 10 psi per 1000 is not far off.
Check this BMW pump conversion out.

https://store.vacmotorsports.com/vac-high-volume-competition-oil-pump-s54s50b32-euro-p1033.aspx

BTW This bike engine had over 200K on it with no issues in fact the engine bearings and cylinders measured withing new spec when I changed the stretched timing chain and were reused. Normal riding was over 9000 rpm for long stretches and lots of full throttle starts for many years. Oil used Castrol RS 10w60.