Posted By: fastmark
Blown up KB 107 pistons findings - 09/17/21 11:50 AM
Posted By: lewtot184
Re: Blown up KB 107 pistons findings - 09/17/21 12:13 PM
looks like some debris was run thru it at some point. i've beat the snot out of kb's for years without issue. believe what you want.
Posted By: racerx
Re: Blown up KB 107 pistons findings - 09/17/21 12:38 PM
Curios was this on an nos motor? I have a RB engine in the garage with a set of the hypereutectic pistons.
Posted By: n20mstr
Re: Blown up KB 107 pistons findings - 09/17/21 12:41 PM
ARENT Those the HYPER U CRACKTICK pistons??
I
Posted By: jwb123
Re: Blown up KB 107 pistons findings - 09/17/21 12:54 PM
If those pistons had .004 side clearance, the engine was assembled wrong. those should have around .0015 Detonation usually starts to lift the edges of the ring lands, similar to your photos. Since you don't know the whole story behind the damage to this engine, why trash KB pistons? I have used them over the years many many times with great results. Engine overheating, excessive ignition timing, poor fuel, etc. etc. could all be factors. Maybe a forged piston would have taken the stress better, no doubt, But I got a couple forged pistons on my shelf with lifted ring lands, do I blame the piston company? Nope I blame the failed fuel pressure regulator that was the root cause of the failure.
Posted By: J_BODY
Re: Blown up KB 107 pistons findings - 09/17/21 01:24 PM
Wish I could say how many passes our old low buck 13-1 compression iron mill had. Was last freshened in the late 90s, but mostly sits under the bench until called to duty. I know I’ve put around 100 on it between our “fun” engine projects. My dad raced it way back when and the short block was also ran in a dirt modified before we got it
. Was originally built as a low buck “claimer” engine. Would I build a “race” engine with them? ….probably not, but here I am!
Posted By: ChrgrCuda
Re: Blown up KB 107 pistons findings - 09/17/21 02:14 PM
What are all of those small looking gouge marks on the top of the pistons? I've also been using KB pistons on customer cars and so far so good.
Posted By: GTX MATT
Re: Blown up KB 107 pistons findings - 09/17/21 02:47 PM
What are all of those small looking gouge marks on the top of the pistons? I've also been using KB pistons on customer cars and so far so good.
Those pistons look like they’ve been rattled to death to me, but that could be debris damage from the broken ring land. What do the other piston tops look like? What do the rod bearings and the bottom of the main caps look like?
Hyper-eutectics are prone to breaking ring lands when they’re detonated.
Posted By: DusterKid
Re: Blown up KB 107 pistons findings - 09/17/21 02:57 PM
In the late 90s my dad built a 440 using those pistons. Only got 2 races on the engine before a piston came apart while warming up the car on the track. Another friend racer of ours with a small block chevy broke a motor around the same time frame with the same pistons. Didn't hear much good about them so we always stayed away from them from that point. Than my wife was running her dad's car around 2014-15 and broke a motor in the burn out. Tore it apart and it had KB hyper in it as well. The engine had several years on it, but what was left wasn't pretty. Couldn't even find the 1 piston as it was in about a million pieces.
Posted By: FastmOp
Re: Blown up KB 107 pistons findings - 09/17/21 03:21 PM
Debri ?
You mean the top of the junky a$$ piston. Lmfao. FN mint. Ha ha ha
Posted By: HotRodDave
Re: Blown up KB 107 pistons findings - 09/17/21 03:49 PM
The way that ring land broke looks like someone stuck something solid in the ring groove (rings butted together) and pried it up and snapped it off. I also would have rounded off the edges of the valve relief. Oh and that is too much piston clearance. Don't follow the directions don't complain when it fails.
Posted By: B1MAXX
Re: Blown up KB 107 pistons findings - 09/17/21 04:08 PM
"The ring end gap on the other cly was .035, which is plenty big enough."
Did that piston come apart?
I get it some don't like them and won't run them , which is ok.
But I have seen these used and pounded for thousands of passes/miles. Hell two of my personal engines have them. They have been getting beaten since the late 90's/ early 2000's.
Posted By: Brian Hafliger
Re: Blown up KB 107 pistons findings - 09/17/21 06:56 PM
Melted down beer cans... THE most world renowned sb mopar GURU...WOW! Just wow....
Posted By: HotRodDave
Re: Blown up KB 107 pistons findings - 09/17/21 07:18 PM
What's the bore size and how much for the other 7?
Posted By: EvilB1Dart
Re: Blown up KB 107 pistons findings - 09/17/21 08:42 PM
I had a cheap, hard-headed buddy that used some 15-20 yrs ago experimenting. Hit the motor with 300 from an NX Gemini Twin Stage-6 plate and MELTED ALL 8 to their A$$! It was on a serious 60' though LOL!!!!!!!!!!!!!! Funniest thing I've ever seen in my life.
Posted By: Bad340fish
Re: Blown up KB 107 pistons findings - 09/18/21 03:19 AM
I hate to see that, my KB107s were awesome. 4 drag weeks in the mid-low 11s, several thousand miles on top of that. Then I sold the motor and it has since been sold again(in a car). As far as I know they are still kicking.
Posted By: CokeBottleKid
Re: Blown up KB 107 pistons findings - 09/18/21 04:28 AM
Ya... .004" on a hyper is idiotic... that would be plenty for a 2618 forged piston
Posted By: Moparteacher
Re: Blown up KB 107 pistons findings - 09/18/21 04:37 AM
Was the piston dropped during or prior to assembly? That would be my guess.
Posted By: 1Fast340
Re: Blown up KB 107 pistons findings - 09/18/21 09:51 AM
Was the piston dropped during or prior to assembly? That would be my guess.
Shhh dont disturb those who already knows it all with comon sence.
Posted By: quickd100
Re: Blown up KB 107 pistons findings - 09/19/21 10:13 AM
I built a 440 16 years ago for my Boss using some KB pistons. Set the quench at .035 and compression at 9.4-1. I set the timing at 34° and it's been fed whatever is at the pump all these years. My Boss pasted away about 4 years ago and his Grandson has the truck it's in now. Still running hard! My guess would be detonation or preassemble damage. You can't hear detonation a lot of the time.