patsmx5

iTrader: (16)

I have been hearing what sounds like a loose bottom end for a while now, and noticing it taking longer and longer to get oil pressure on cold starts. Hot starts it's almost instant but you do also hear more noise on hotstarts for a split second too. Also, I'm feeling a vibration from around 4,500+ RPM that is pretty concerning. There is no knocking, well, maybe a light tapping. Mostly just what sounds like a whirring sound on startup that is way louder than it should be, and then quiets with oil pressure but doesn't go away, just goes to about 1/3rd the volume. This bottom end has seen 9K RPM and 40 PSI boost, I ran 10W-30 Castrol GTX conventional oil, and oil temps have never been above 220*F ever, normally runs 205-210*F on oil, coolant run 195-200*F. I do oil changes every 800-1000 miles. The rev limiter has been at 8K for the last 10 months though. The last several oil changes have showed metal in the oil as a fine fine glitter like look, but no pieces or chunks, just really fine metal suspended in the oil. I did an oil change yesterday, put about 50 miles on it and then today after trying a few things to see if I could make the vibration go away, I decided to drop the subframe and pull the pan and inspect bearings. It's 2AM so I only got one rod bearing out and took some pics, pics below. These are the ACL RACE bearings, all were standard size when put in service about 2.5 years ago.

Thoughts? How does this look? I will plastigauge the bearings tomorrow and inspect all of them and post more pics of what I find. Wondering if I should change anything on the setup? My plan for now was order new bearings, throw them in, drive the car till the weather is crap, and then do a refresh/rebuild if needed. If I can identify why these bearings are wearing out (I think/suspect they are) then I can do something different (different oil, thicker oil, less RPM, something).

Some pics are with flash, some without. You can see the wear if you look near the edge of the shell, it's a different layer showing there. And obvious scoring and whatnot, you can feel it with your fingernail.

nitrodann

Corresponding scuffing on the crank?

Dann

ryansmoneypit

iTrader: (6)

somewhat irrelevant here, but on my dirtbike that revs to 14k, a bearing like that is a death sentence.

Leafy

iTrader: (1)

This reflects what I was experiencing with my BP at high rpm. You probably could have just limped this to the winter by changing the oil more often if you caught it when you first noticed the oil pressure issues. High rpm BP just shears the oil to death and the viscosity goes down rapidly and then you get low oil pressure. I was destroying T6 in 1 autox of spinning to 8.5k. I switched to the valvoline vr1 10w30 synthetic and it would last much longer and oil analysis looked much better, but it was still a ticking time bomb with that redline.

Maybe an even higher flowing oil pump than the vvt street strip would help. Maybe drilling out and chamfering the oil passages in the crank would help too along with a higher flowing pump. But it's a struggle. I'm not sure how much higher flowing you can go with an on crank BP oil pump.

afm

iTrader: (3)

Clearly the solution is to install a 55-gallon oil drum in the rear of the car, along with an elaborate system that continuously changes the oil while you drive.

aidandj

iTrader: (5)

Cleans, filters, and repurposes. Along with a dry sump.

And an e85 still. So you just have to add corn, wait a few months and drive.

patsmx5

iTrader: (16)

Gonna pull some more bearings and see what it looks like. I ordered a new set of mazda bearings, probably gonna try those and see what happens. I've never seen bearing wear this bad before.

patsmx5

iTrader: (16)

Crank is not perfect, but it's nothing like the bearings.

I checked all the rod bearings, the one I posted pics of here had the most scorring, but others were similar. I checked two main bearings so far, both looked better than rod bearings but showed similar wear.

Savington

iTrader: (31)

10w30 group 3 "synthetic", 40psi, 9000rpm on a stock crank. I'm not surprised, I'm not sure why you are surprised.

andyfloyd

Are you running a boundary High pressure pump? I would be running mobil 1 15w50 in that thing as well. I always loved that oil because it would keep a nice pressure even when hot.

concealer404

iTrader: (3)

I'd mostly be.... not revving a BP crank to 9000rpm.

ryansmoneypit

iTrader: (6)

Street outlaws only get like 4 passes on a set of bearings. I think you are ahead of the curve.

patsmx5

iTrader: (16)

Yeah to make it worse, it was conventional oil not the fake-synthetic, but I did keep it fresh.

The plan is to keep the revs down for a while, and switch to a much better oil and finish the season, and go from there.

Running the stock pump. I will look into the oil you suggested. This is the first time I've had bearing problems before, I'm mostly surprised because this has never happened before, and I didn't think I'd pushed this motor that much harder than previous motors, but clearly I was wrong.

patsmx5

iTrader: (16)

Noted. I'm not gonna do that anymore.

I didn't know that... Either way I want to do whatever is needed to improve the setup so this doesn't happen again.

The bottoms side of all the rods bearing look a lot worse than the tops, so that suggest RPMs was hurting the bearings more than power was.

sixshooter

iTrader: (12)

I would definitely polish the crank. Oh, yeah. Polish that crank.

What oil are you going to run? Redline, Shaeffer, Amsoil, something else?

Savington

iTrader: (31)

If I were building a BP to tolerate that kind of abuse:

-Billet crank
-Billet caps
-Sleeves
-ACL HX mains/rods
-Amsoil SAE60
-Boundary allofit pump

ryansmoneypit

iTrader: (6)

Sav, why do you suggest 60 weight oil? this always creates a flow vs pressure argument in recent..

aidandj

iTrader: (5)

I have a set of these I'm looking to unload...

https://www.miataturbo.net/miata-par...earings-93248/

concealer404

iTrader: (3)

Bearings like my condoms. Baggy.

Art

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