rod stretching carnage.
 

So, 2 days ago, my motor got over-revved. I am now following the tow truck. A rod exited the block. I was headed down a hill, I came into boost in 4th and around 10psi and 4000rpm, the motor studdered and died. The road and car behind me were covered in oil. There was no detonation. I will post up pictures later. I'm on my blackberry and I've been up all night.

ouch. that sucks. Time for a build?

I assume those are stock rods... just in time for the $299 special.
Do you have a dyno graph... or just tell us how much torque the 2860 is making for you.

Yep. Stock. I don't know an exact number. Enough to go 12.6@112. I'm guessing 280wtq.

Did the motor actually spit the big end of the rod completely out of the block? Don't see that one to often.

:/

Any estimate as to how high you overreved?

This kind of thread kinda bothers me in a way. I've accidentally made the 2 -> 1 shift on two occasions. Wasn't logging either time so I don't know exactly how high I went, but it sounded interesting. And yet I still haven't expelled any rods through the side of the block. I can infer from this that either it was a really good day in the Osaka factory when my stock rods (and rod bolts) were made 18 years ago, or I'm a pussy and don't push my engine hard enough.

That sucks, Wes. I have a complete 99 long block (minus throttle body/ iacv) in New Albany if you are interested.

Yep, boost in, rod out. Hopefully i can get pictures of the block. It's fucked as well as the oil pan. There is a gash that i (from what i can feel) goes from near the bottom of the oil pan to as far as i can reach behind the starter. Maybe a 5" long split.

Well, i let someone else drive the car.:vash: but it was an all out 1-2-1 so whatever going from 7krpm in second to first is. Maybe someone with a gearing chart for the 6 speed with 4:10's can tell us.

Yeah, i wish you the best of luck. As soon as it got overreved, i knew that something bad was going to happen. Why i decided to go 1.5hrs away and race ppl, i dont know.

Hmmm, i may be interested in the head/intake. I have a bottom end already.

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god damn man that shit will buff out :hustler: . Im sorry to here about your loss man.

Final drive ration for 6 speed with 4.10 is
1st = 15.416
2nd = 9.3029
So assuming he dropped the clutch back in first at 7K and no lose of speed occurred during the "perfect" shift
15.416/9.3029 = 1.657 overdrive * 7000 = 11599 RPM

Well, there we go. revving to 12k will make your motor pop. Who knew?

So, the rod bolt is mostly in tact. Does that seem strange to anyone else?

maybe thats the fail point maybe it backed out and your rod and piston floated freely untill the crank came around and well the ignition..... idk just a thought, well time for the build, sorry about the loss there

Wow! Sorry to see that! Good luck in the ensuing project!

Isn't it such a great sound hearing your rod go through the block and pan?

In for many pictures when you get it out.

Haha, great? I'm not sure. Interesting? Definitely.

So are you going to swap in another stock engine and continue the experiment, or go built?

So I have decided that when my motor throws a rod out the side I am making it into a bad ass table.....

I really dislike these threads... :(

I already have another bp block disassembled and i am buying forged rods and pistons this week.

Hell yes, that's what i'm going to do with this one.

Haha, dont worry about it, if it breaks, it breaks, nothing you can do about it. Are you going to turn the boost down? Didnt think so.

Need boost first.. :laugh:

These just scare me.. not that I really give a shit if the motor in my car grenades, cause it very likely will.... It just scares me to think my built motor might.

Wes -

Sorry to hear about this. Hopefully the guy driving is going to pitch in on the rebuild...

First question that comes to mind, "How do the threads look?"

- L

What's up with racing stock Corollas? And nice window stickers.

its really nice to have a built motor, with relatively little power going through it.

The threads are fine all the way up to the last 2-3 threads.

Who the hell was driving your car? Are they taking responsibility?

It's a long story but he did offer to help me out. He doesnt have much to help with though. Oh well, i was wanting to build the motor anyway.

What road is that in your video? I think I've been pulled over there a couple of times!

Sorry to hear man. But I guess a 2-1 shift putting you at 12k will do it.

At least tell your friend he has to be your tool bitch while you work on it, however many hours it takes, he's only there to get you tools......and beer.

Goodluck with the rebuild! :bigtu:

Sorry to hear man. I was really looking forward to seeing how far you could take the stock motor. I'm sure you'll do some crazy things w/ the new one though. Good luck with the rebuild. :bigtu:

Yeah, i'm sure it would have stayed together had it not been overrevved.

Agreed. Thanks!

It is hwy 135 between corydon and ky.

Wow, thats crazy. Looks like a cap failure before an actual rod. Otherwise why would the big end get split and bent out of shape like that if the other end was already broken.

Could stretch the bolt, lose the tension, have the nut back off. Someone who has the bolt should measure its length compared to all the others.

Makes me wonder if the stock rods would work better with ARP bolts in them.

I'd like to see the bolt and nut up close.

Have some rod bolts from my other motor. I will get a mic and measure the bad one to normal ones.

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You fail at image cropping.

OTOH, that is damned odd. The threads are not completely stripped from the rod bolt, nor from the nut.

Weird, but that is going to make an awesome table...pics of the block?

Nice pics, very interesting.... sorry about the loss but save that junk for show and tell!

Indeed. It's like the nut backed off the rod bolt. That seems like the only logical explanation and that doesn't seem logical.

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I will get better pictures once i get the motor out. Probably a couple of weeks from now.

18psi = vanishing rods?

Haha, jk. Sucks man, sorry to hear.. cant wait to see what your built motor does in the 1/4.

if i didnt know any better i would say your bolt backed out but wtf doesnt seem possible. Seems like the main bearing lower was the first to fail, and with it the rest. I wonder if some loctite or lock washers etc would have helped in that case?

It's common knowledge in the engine building world not to use lock washers or loctite for any bearing or main caps. Technically speaking if you know the physical properties of the nuts and bolts you're tightening and torque them to the correct torque, you will never need any locking devices, liquid or solid.

That said, with rod studs you want to 'set' the studs into the rod. Torque them, loosen them, and then torque them a final time. The first torquing will pull them all the way into the rod, and the final torque will keep them tight.

wes65, these are just general engine building tips, and in no way insult your engine building skills, if you did indeed build this engine. 18psi and 12,000rpm (which I highly doubt your friend did, btw) will kill just about all of our motors eventually.

No, this motor was put together by mazda 15 years ago. :) held up quite nicely, i think.

Like SolarYellow said, I wonder if ARP's would have stopped this. Everything I've seen, people say they aren't needed, but this seems to show otherwise. First cap I've seen fail on a Miata. Sure its happened before though.

I think it would have but if you're going to have the motor out anyway, why not put forged rods in?

considering it didnt strech then we are assuming the increased RPM crushed the bearing and allowed play in the system allowing the nut to wiggle free via vibration?

Even if the bearings were completely flat, wouldn't the caps still be snuggly against each other where the bolts go through. Perhaps the bolt didn't streatch in total length, but the threads may have given way just enough to let the nut become loose. Only way I can see it happening.

Sounds like the only logical explanation. It just seems odd.

My hunch is that the bolt stretched just enough for the nut to then be loose enough to back off. Looks like you dominated your starter too.

Are you interested in that 99 head? I'll be in New Albany from Sunday through most of next week and will be stripping the parts car. Give me a shout if you want to check it out.

I've suggested at least a thousand times that with my bandsaw and heliarc welder, I can repair anything. After looking at your con rod debris, I think I'll tone that down a bit.

Haha, how about i send you the pieces and you take a shot.:laugh:

and you could probably sell them to the guy on miata.net who was "building high compression pistons" after he blows his motor.

UPDATES!!!

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