AlwaysBroken

So basically you mean a fresh junkyard motor that isn't full of metal shavings. I agree that has merits, I'm just not sure it's necessary yet. To be completely honest, I don't think the oil pump has actually failed. The smaller chunks of the piston got sucked against the oil inlet grill and wedged there, which wouldn't have happened with a busted pump. It's definitely possible that there are small pieces of metal inside the engine and I'll definitely check the rear cam journals for damage and washed up metal grit (the rear intake cam journal seems to be a magnet for this sort of ****). I'm also taking out the oil pump for inspection, taking out the rods and examining the bearings, etc etc etc.

Pepino

So at end, squirters in or squirters out?

18psi

iTrader: (76)

I always make them squirt

Pepino

you cool boy...

AlwaysBroken

I think squirters are probably safe if you torque and loctite them like crazy. I think there is some validity in the whole "ceramic coating without squirters" approach but I don't have more than second hand anecdotes to share.

patsmx5

iTrader: (16)

There are a lot of OEM applications that use piston squirters with cast pistons, and no squirters with forged pistons.

The reason is that cast aluminum turns from strong to play dough at a lower temp than forged aluminum alloys used. So oil squirters make a big difference in strength/reliability by knocking off some of that heat to keep them in a temp range where they're still strong. Good cheap solution that works.

This just isn't an issue with forged pistons, their strong to playdough knee of the curve is at a higher temperature where oil squirters or no oil squirters doesn't really make any difference in strength.

Also forged run higher clearances vs cast due to higher rate of thermal expansion, so oil control can be a bigger issue and running oil squirters with forged pistons exaggerates this.

AlwaysBroken

With E85 I assume this isn't even an issue since you run cooler anyway.

Mazdaspeeder

I have the non-FM Wiseco 8.6:1 pistons and factory squirters, no issues. I see some builders always use them, some never do. Don't know who's right or wrong, but my system has worked for me.

AlwaysBroken

Yeah for the record these were non-FM wiseco 8.6:1 bought somewhere circa 12 or 13 years ago. Never had issues with them hitting the squirters, or issues with piston slap, etc. They were great until this happened.

Savington

iTrader: (31)

The notion that your squirter came loose and fell out is ridiculous IMO. I have never seen that happen, and the fact that you have an entire skirt's worth of piston missing on the same cylinder where your oil squirter has mysteriously popped out leads me to believe that this has nothing to do with the oil squirter.

Since you've now run the motor with no oil pressure, all the bearings are likely shot, so it's time for a full rebuild.

AlwaysBroken

I already said it's ridiculous, but I don't have a better explanation.

Also, I agree the bearings might be shot, so I'm going to look at them.

Mazdaspeeder

So here's another question maybe was answered. Did you find the bolt and squirter anywhere in the pan? I would think if it really did back out, it would have caused a lot of other damage in the process between the squirter, washer, and bolt being knocked around by the crank.

Maybe someone never installed the squirter and this is just a coinsidence?

AlwaysBroken

Once again:

These pistons and oil sprayers were installed in the car.
12 years later, the car suddenly lost oil pressure. I pulled off the road and got it towed.
When I dropped the oil pan, there were pieces of piston skirt in the pan.
The squirter/bolt itself was also in the pan, in a bashed up condition.
The side of the piston where the skirt was destroyed was the side where the sprayer is located.

Before I took out the engine, I thought the oil pump had failed. Since seeing the above, it seems that the piston skirt and the oil sprayer hit one another. There is nothing besides the sprayer/bolt and skirt metal that I found loose in the engine. There is nothing visibly damaged in the engine besides the piston skirt and the sprayer. Since nothing else could have hit them, they must have hit one another.

If this was some sort of gross assembly error, I think it would have happened way earlier. If the squirter wasn't installed, I wouldn't have had oil pressure in the first place.

patsmx5

iTrader: (16)

I would agree that based on what you posted and found so far, it appears the bolt that holds the oil squirter into the block vibrated loose, and that caused the failure.

If that happened after 12 years of being boosted, I'd say that's a testament to how well that engine was built for it to last 12 years. That's OEM level of engine reliability.

Sucks it came loose. I'd probably start by checking how tight the other squirters are. If all of the others are tight, I doubt that one was undertorqued.

codrus

Speculation: Perhaps the bolt backed out a few threads for whatever reason (vibration, not torqued well enough, whatever), the squirter rattled around on it, and at some point got cocked in such a way that it hit the piston and broke the skirt. Later the bolt loosened the rest of the way and it and the squirter dropped into the pan.

--Ian

Midtenn

iTrader: (15)

Pictures of what was in the bottom of the oil pan?

AlwaysBroken

Regarding piston options, I was thinking supertechs from 949 but part of me wonders if it wouldn't be better to get coated pistons from FM even though they cost a bit more.

Thoughts? The pistons currently in the car are the wiseco 8.6:1 units.

patsmx5

iTrader: (16)

Weisco alloy is stronger. You just got 12 years out of a set of them. Pretty sure that would be enough to get me to run them again.

I do recommend the FM units. They are better design than the off the shelf weisco's. Call FM and they will tell you the differences. I asked, they told me, and I bought them. I don't like to waste money on stuff I don't need, but their pistons are the strongest off the shelf miata piston you can buy IMO.

Savington

iTrader: (31)

Unless you are looking to break the 500whp mark, the extra strength of 2618 over 4032 is completely irrelevant. The smaller thermal expansion of the 4032 will make for a quieter motor at cold start.

Evaluate your goals. Do you want a noisy 600whp-capable motor, or is an OEM-quiet shortblock that might only make it to 500whp good enough for you?

AlwaysBroken

I dunno, the wisecos were never noisy for me, at least nothing I could hear over the exhaust. I guess that settles it.