Drilling main/big end bearings

[Guest]

Has anyone ever looked into or had it done on a EJ? Sure STM started doing it a while ago for evos and theres some new bearings out with two holes instead of the one. Wondering if it would help B/E issues?

General question no way in hell I would strip engine just to do it.

[NomadGonad]

I though it was a prety well known trick when building big-ish HP EJ motors.

Engine builders in the US & OZ have done for a number of years.

[rex-leggy]

i figure that would cause some bad things with oil pressure.

there would be ways around it which would cost more$$

even the cross drilled cranks use the same bearing so i see no issue with oem

[Paimei]

THe cross section area on evo bearings is greater though in comparison to the narrow EJ bearings which are a product of the boxer crank configuration. When you remove material from a bearing face by drilling a hole(s), remember you are actually reducing the CSA further so the extra oiling is not necessarily helpful. This is more of an issue for the big ends of course where uniformity of the bearing face and clearances are critical.

[titian]

Hand grooving can be done. VERY carefully with a diamond point tool. or triangular scraper if you know what you are doing and have the know how ability.

Correctly done these X cuts into the bearing face will aid the "michell" lubrication theory or wedging effect that keeps the bearing surfaces apart.

Beats two holes and loss of bearing surface area.

[D-Style]

Playing around with the oil holes is a black art. Even little changes in the angle of the holes chamfer has different effects. Theres a few theory books (manily on V8\'s) which go into good detail about bearing design.

I think Keep to the basics with regard to this, oil flow, oil pressure and correct clearances.

[Subirex Automotive]

i did one on my legacy few years back after the beb blew on me. never gave me problems with beb after that mod. the car is sold but still running strong.

now i have seen the ACL bearing have two holes as well.

[Paimei]

 titian said:

Hand grooving can be done. VERY carefully with a diamond point tool. or triangular scraper if you know what you are doing and have the know how ability.

Correctly done these X cuts into the bearing face will aid the "michell" lubrication theory or wedging effect that keeps the bearing surfaces apart.

Beats two holes and loss of bearing surface area.

I experimented with this technique back in the late 1990s on my race engine to see if I could improve on pick up on the crank I was seeing at the end of the season. I bought jeweler\'s illuminated and magnified spectacles so I could see the residual ridges left on the bearing faces either side of the grooves and polish them off with a very lightly abrasive cloth. I alternated seasons with grooved an non-grooved faces and it made no visible or measurable difference.

I concluded that without any visible or measurable improvements, and the fact that I was not experiencing complete bearing failures before or after using this technique, that without access to a control engine on a test rig backed up by detailed oil analysis, I could not validate whether it made any difference and discontinued as it wasn\'t worth the hassle.

Over the years with the EJ engines I have built for both competition and non-competition purposes, I have found that the biggest influence on longevity of bearing life, particularly the big ends, is a combination of very close scrutiny of the bearing faces and the correct clearances, assuming other hygiene factors such as oil quality, pressure and temperature are satisfactory of course.

I examine the bearing faces with my jeweler specs to look for protusions and imperfections not visible with the naked eye before I put a mic anywhere near them. Due to close examination you would be amazed at the number of sets of bearings I have returned to a very reputable competition bearing manufacturer due to bearing faces being lightly damaged in packaging or the bearings themselves containing FOD due to poor quality control in production.

I have also found that there is a specific clearance which you must stick to exactly and consistently for the big ends for the best results.

[titian]

Re Above=E:- Nicely said. 8)

Tis a black art for sure. One day some one will put a camera inside an engine to "see" a bit more of WTF is actually going on under extreme loads and rpm. Then slow it down. Now with our current digital technology and slo mo this cannot be far away.

Im guessing you have also discovered that the factory bearing clearance can be improved upon to provide better bearing life. Well done that is a serious issue! Also a proper engine Guru secret. 8)

Nothing quite like a "clean" set of bearings to start with either.