I read the whole thread. To me it does not make sense to have such issues on three motor builds...

Most probably during the clean up and reassembly something was missed and the engine was contaminated again and again...

What clutch are you using?

Engine oil on my built motor i was using 20w50 Valvoline VR1 or Valvoline Premium 10w40 in the winter... No issues never...

 

I am wondering about the mainline and thrust in the block at this point. Without an oil pressure gauge its hard to say, but I strongly suggest it this next time around. New oil pump each time?

Aaron

 

Get a whole new engine/head accessories and start there. It's really hard to clean out everything.

 

one of the reason i am asking for the clutch...

I have read and heard about motors go because of a heavy presure clutch and not proper adjustment pushing the thrust bearing to much and eating little pieces contaminating the motor... Maybe far fetched but...

 

Thanks curt.. the car did see some detonation here and there due to boost creep from cold weather.. I would simply turn the boost down..recently I went wot in first and car fell on it face almost like it hit a wall. Only in first gear though..

 

New oil pump with Buschur motor. I would assume Buschur would check that stuff you mentioned?

 

Act hdss

 

detonation + 10w30 = spun bearing.

 

I'm sorry if i missed...but who tuned your first motor? Near 30psi at only 100 milies seems kinda early?

 

Mitsu cranks are Nitrided coated as has been mentioned in the thread already.
The coating will usually be about 0.030" embeded into the surface of the journals.

I have built many a DSM throughout the years and on a stock rebuild I run 10w-30 or 10w-40.
When I build a motor for more than 600hp I will be setting bearing clearances looser and on these motors I will run 20w-50, either Brad Penn or off the shelf VR-1

Always start with new Parts especially anything that has to do with having motor oil running through them(That includes the turbo as well).

The failures that you are having seem rather strange though.

I do not want to point the finger at anyone here but It sounds to me that the tune on all 3 motors were possibly borderline race tunes more or less. You probably saw enough detonation to spin the bearings.

Start off fresh, Run a quality 20w-50 motor oil if bearing clearances are looser than stock and keep that knock in check.

 

I'm in the same kinda situation.. After a tear down, metal catamination in the oil cooler seemed to be the culprit...

 

so knock has something to do with spun bearings also?

 

no definitely not. lol.. tune is more then safe.. he could of spiked higher then we tuned it for and still had leg room.. so its certainly not from seeing 2-3 knock counts randomly at best on rare occasions.

you'd need some serious detonation to spin a bearing.. and i dont tune aggressive like that..

look at the piston tops and rings.. better yet do a leakdown / compression test.. i guarantee you the engine is very healthy in that aspect.

 

Knock can cause premature bearing failure.

Picture this. You have an engine built for a high HP application. Normally this would mean looser than OE specs on the mains, rods and the PTW clearance to name a few.

Since we know that bearing clearances are on the loose side and we run a thin oil in the engine(say 10w-30) you are left with a weak film strength around the journals.

This weak film strength will basically when you get detonation it will disperse off the rod journal.

Lets picture the engine apart. Say you had the piston/rod bolted to the crankshaft. Now hit the top of said piston as hard as you can from the top. The oil that is between the bearing and the journal will be displaced. Kind of like if you tap your foot in a shallow puddle of water the water will be displaced outwards.

Now if you did the same thing but had a thicker oil(20w-50) you would have a stronger film strength surrounding the bearings and it would take more detonation to cause the oil to be dispersed from the journal.


OEM spec motor should be run with a thinner viscosity oil as this yields the greatest film strength.
Looser motors should be run with a higher viscosity oil to yield the greatest film strength.

I suspect the OP's first 2 failures could have been from contamination. The 3rd motor from Buschur would have had looser tolerances and couple that with the thinner 10w-30 then it would not take much detonation to cause bearing failure.


As far as knock is concerned, 2-3 counts is quite a bit for a daily driven car. If you got on the car at least once a day and you constantly saw 2-3 counts of knock then it adds up quick.

A daily driven car should be tuned for 0 knock, none. If it means you have to sacrafice some power so be it. Better safe then sorry.

 

thanks for clearing that up that was very helpful

Im on a stock motor right now and running Shell Rotella t6 5w40 here in nyc am I ok with this?