Engine blew up! Help analysing possible causes

What happened
After a nice day of easy road cruising I decided to add some highway miles. Everything went okay and she drove as always. I'm an "objects in mirror are losing" kind of driver, so it was spirited driving with a bit of sprinting here and there. No endured high-speed driving though, as the highways were too crowded for that.
How it ended
Then, before heading home, I decided to take one last sprint and used the kick-down from a highway insert. Starting at a speed of about 20 miles I pushed the pedal and we hurdled onto the highway. About half a mile further along, at a speed of... 80/90 miles a sudden blow, rattles all over and a sound like I was driving through gravel. White smoke and oil all over...
First I checked if I hadn't just lost my v-belt, causing the engine to overheat. But those were still in tact and the wetness was on the driver side at that. One look down and I knew I was .... because there hung what only could be a piston ring.
How do I determine the cause?
Not quite sure I want to build another engine or just buy a crate/already built and be done with it. However in any case I want to know what went wrong here.
Given this side blow-out. What should I check next/first?


Both plugs on nr.'s 5 and 6 looked like this and for both cilinders a rocker has been forced aside. Note the sludge I found under the carb and in the intake.



Here are pics of the cilinderheads, crank, camshaft and rods.
Left cilinderhead:

Right cilinderhead:

Close-up left chamber for nr. 5 cilinder:

Close-up left chamber for nr. 6 cilinder:

Close-up nr. 5 piston rod:

Close-up nr. 6 piston rod:


Last edited by worship79; Dec 22, 2018 at 05:07 PM. Reason: Pictures addes
Then things began to get worse, worser, worstest. Hard to say. Is the piston missing? Can't see.
I am no expert on throwing rods but I would say, that may not buff-out.
Sorry for your loss. Thankfully winter is coming and the best time to regroup.
Last edited by HeadsU.P.; Nov 25, 2018 at 11:37 AM.
Need to tear down a bit more to see what failed first. Could be a piston, pin, or rod bottom came apart. One of those let go and the crank came around on the next rotation and smashed the rod out the side of the block. My guess money is on a hypereutectic piston disintegration first but it could be any one of the other things let go first.
New engine time for you....Have you been a good boy this year? Maybe Santa will bring you a short block?
Then things began to get worse, worser, worstest. Hard to say. Is the piston missing? Can't see.
Need to tear down a bit more to see what failed first. Could be a piston, pin, or rod bottom came apart. One of those let go and the crank came around on the next rotation and smashed the rod out the side of the block. My guess money is on a hypereutectic piston disintegration first but it could be any one of the other things let go first.
New engine time for you....Have you been a good boy this year? Maybe Santa will bring you a short block?
Santa has me looking at a 400 block, bigblock, LS, another stroker...
And given that side blow out.....the only thing to check is which one of your friends has an engine hoist
Last edited by OMF; Nov 25, 2018 at 12:17 PM.
The Best of Corvette for Corvette Enthusiasts
Last edited by derekderek; Nov 25, 2018 at 01:32 PM.
I can tell you when I did my 355 L-82 build in 2014 and mentioned hyper pistons innocently just for feedback, my builder who did the bottom end of the motor, said he would not do the bottom end of my motor with hyper pistons. He said "they are junk" and will implode at the slightest detonation. I used JE Forged racing Pistons (pistons alone were about $700/set). I reconditioned my L-82 forged crank, reconditioned the OEM L-82 forged rods, with new ARP bolts everywhere etc. It was expensive but I was going to do as much as possible to avoid the terrible outcome you have just experienced. I was building a fairly stout 355 L-82 and was not going cheap anywhere. Not a fan of Bill Clinton but I feel your pain....
Last edited by jb78L-82; Nov 25, 2018 at 03:13 PM.
@ jb Correct: bottom end not forged, did use all ARP bolts throughout.
@ Derekderek: heads are Edelbrock performer (60909) with CompCams 1.52 roller tip rockers. Heads have been cc-ed en springs shimmed. Block was zero decked, and torqueplate honed.
@ Big2Bird: as it looks, I can reuse the top end and perhaps my XE274H nitrated camshaft + comp dual chain, etc. This is relatively expensive over here and there is not a large market to sell them on to (without considerable loss).
I'll be pondering my options for a while I guess.
Hang on to the block and four connecting rods. That will make a hella of coffee table with a story behind it. If you have never seen a bare block coffee table with con-rod legs, I believe I spotted them on Etsy maybe? Or try Google pictures. Radical stuff for a man-cave.
Last edited by HeadsU.P.; Nov 25, 2018 at 05:44 PM.
I am a believer that it all started with the connecting rod....as what we called them at the drag strip a 'rodney'...because they would often times fail and sometimes it was a piston literally melting down and then cause catastrophic damage to an engine. I have seen enough oil pans that when they were pulled off that what was laying in the bottom of the pan looked like a hand grenade was set off inside it.
DUB
Last edited by ddawson; Nov 25, 2018 at 06:38 PM.
@ Big2Bird: as it looks, I can reuse the top end and perhaps my XE274H nitrated camshaft + comp dual chain, etc. This is relatively expensive over here and there is not a large market to sell them on to (without considerable loss).
I'll be pondering my options for a while I guess.





Good luck, keep us updated
At least store the numbers matching block for any potential buyer down the road.
LMAO

lesson learned.
Whatever you replace it with use quality parts.
An LS or big block would be a fun build.
















