I tapped extra holes around the perimeter to help pry the oil pan off next time.

I welded on the oil return. I warped the crap out of the cover but it still bolts down flat.

 

So turns out that I hadn't even turned it up to 7800. For the first year of it's life it ran 7200. All of last year it was set to 7500. This June I read that Kpower ran theirs at 7800 so I figured 7600 would be a safe number. I know all this because I went through save files on my laptop to see what the history of my setting were.
The replacement engine is in the car and running. I set the limiter to 7400. I really want to build an 8000 rpm engine but it's so nice to be able to swap a junk yard engine. Although I really don't want to go through it again.
I wish I would have had my sd card in and logging at the time. I was running solo storm and it shows I was doing 59.4mph which is only 7250 rpm.
Now that the car is out of the way and running. I will start pulling apart the dead engine to see what I can figure out. I already know the big end and little end are still together. The rod broke in the middle. It's hard to say why.

 

Looks good to me!

 

I second that. 3 looks pretty obviously bent, but the other two I can't quite tell. Looks like they might be a bit out of shape as well, no?

 

1 and 3 for sure, but probably all of them. At least it's not just a BP thing 😂

 

Ya they all are bent. I'm not sure it was running like that or it happened from all the crap that went through the engine when it destructed.

Rod three be like that sometimes.

 

I would suspect #4 looked much worse than 3 moments before it exited the chat. Try ramping in a lot of retard close to redline, aka a "soft" limit, should also play nice to the rods, although I'm sure some upgrades are on order.

 

I ran a K24A swapped Acura RSX for a couple years in time attack/track day settings. I had followed the "Honda forum advice" of removing the balance shafts to install a K20A2 oil pump to support flow at higher RPMs. Also I ran an oil pan baffle and they seem to all be made for use with the K20A2 pump.

In hindsight I wish I had left the oil system alone and kept the balance shafts. The K20s are ok enough with no balance shafts (86mm stroke) but the K24 had horrific NVH. I had to use Hasport's softest mounts just to make it tolerable. Even then when the engine was revved up it sounded and felt harsh; not smooth like every other car I've tracked. When I dyno'd my K24 it made its peak whp from 6800-7200; so it turns out that changing to a K20 oil pump was totally unnecessary and only made the car worse. As I talked to other K24 users at Gridlife I learned that some of these teams go through 3 or 4 engines in a season! They were revving them to 8k+ to hold their gears and the engines weren't holding up, even naturally aspirated. As I learned about mean piston speed, this made sense of it all; the factory redline was actually there for a reason (Honda did the math). These engines are not K20As or F20Cs, you cannot use them the same way.

My takeaways from my K-series times: K24s should always keep their balance shafts; if you have to change the oil pickup or pump to make it fit, this is not the swap for you. K24s should always stay below 7500 rpm. And K24s should stay naturally aspirated; if you need more power than 220-230 whp, then you need a swap with more displacement. When you take the K24 outside of these parameters, the reliability goes into the trash.

 

I don't know how to put this but I did it again. At least the rod is still inside the block this time. At least I have a real datalog of the destruction this time. Same senario, 2nd gear rev limiter. 7100rpms. bang.

 

Damn dude. Sorry to hear this. In for carnage pics.

Sometimes I wonder why we do this to ourselves.

 

Me too.
The carnage isn't nearly what is was the first time. So there might be something left to look at. Pulling engine now.

 

I was glad to see that this failure didn't scare you from hitting the limiter altogether. Jeremy's car seemed to be fine bouncing off of it on Sunday

In for carnage as well

 

This is wild. The rod looks crushed. The bearing is fine. The journal is fine.

 

Any damage to the head? Dropped valve, broken piston, FOD in the chamber?

 

Just a bent intake valves on cylinder 2. Probably repairable.

 

This engine was in perfect condition and then the rod snapped. The bearings are all good. Minor crush on the top rod bearing in 2. But that is expected. It tried to excavate the cylinder. The pistons all had zero detonation marks and the wash was the same on all of them. Even piston 2 looks reusable. The rest of the rods are straight unlike last time. The crank is probably reusable. 0.0005" out as measured on center journal. This wasn't caused by knock or oil starvation. The head gasket and coolant are clean so it wasn't head lift.

The rev limiter I have setup starts dropping cylinders at 7100 rpm. It cuts fuel to cylinder 1 first and also starts dropping spark to random cylinders. I can't imagine spark cut would hydrolock a cylinder in less than a second. Maybe these rods just start cracking and give up at high rpm? It's not even hitting stock max rpm of 7300rpm.

I am going to turn off progressive fuel cut and spark cut and just do spark retard soft limit and cut both at hard limit. Or maybe just hard cut fuel. I need to figure that out.
I also want to build an engine with rods. I don't want to change out the pistons so I don't have to bore the cylinders. So I have to find some stronger rods that connect to stock pistons.

 

Wild that it would squash the rod like that and not damage the piston. No idea how that would happen. At least some of it is salvageable.

I wonder if the rod stretched a bit and then folded over after it was weakened? I would expect the head would show more damage if that was the case though.

 

Ouch, extremely weird failure. I'm with Sim, it's gotta just be a defective/weakened rod, right?

What was the backstory on this engine and how many runs did you get out of it?

 

Think you just got unlucky with this one. Agreed that looks to be a straight up rod/metal failure from looking at the grain patterns at the break point.The bend is from it smacking the block wall after the piston sheared off and contacted the head.
Don't think any of your rev limiter settings caused this as it most likely happened on the up stroke, when the rod is under the most tensile stress at TDC.
Throw a new one in and see if it happens again... You know, for science and stuff.

 

Time to throw in the towel and LS swap it. (I am an agent of chaos)