busted ls
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busted ls I stroked a 6.0 to a 414ci. It has an eagle rotating assembly. It has a 4in stroke, h-beam rods, an -4cc flat top piston. We put it on the engine dyno last weekend and number 1 piston was destroyed. Busted the block. Gave the head hell. The dyno guy said it was detonation. It has a 850 holley carb, holley single plane intake, and a MSD LS. The first two pulls it made 540 hp with 24 degrees of timing. The third and finally destroyed pull was at 28 degrees of time and made 560. He checked the brake pacific on the second pull and said it was rich enough. My question is has anyone has this setup and what timing are you running. All the pulls was done on 100 octane avgas. I can't believe that detonation killed it and that quick.
He had no wide band to watch air/fuel? I don't imagine that it was lean enough to cause that much heat. And that timing on that low of compression? Power seems that of a LS1 with heads and cam. Weird.
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I first thought maybe a bad venturi/blockage in the carb leaning out that cylinder, but with that much HP something had to be working right.
Expensive failure I would imagine.
How does he know it was detonation and not something like a piston failure or piece of debris/valve hitting the piston?
Expensive failure I would imagine.
How does he know it was detonation and not something like a piston failure or piece of debris/valve hitting the piston?
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From: Harford Co. Maryland
Betting it wasn't detonation.....you would have head it that bad before it broke.
Also you would see it in the other cylinders
I would think....
ring gap too tight, butted, and the rest is history
bad piston from the get-go
piston came out too far at the bottom
just to start with
Also you would see it in the other cylinders
I would think....
ring gap too tight, butted, and the rest is history
bad piston from the get-go
piston came out too far at the bottom
just to start with
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The first pull at 24 degrees it had an intermittent miss at 5000rpm. We checked all the connection and made another pull with the same results. We went to a colder plugs and the next pull we went up to 28 degrees. He took a look at the first set of plugs with a magnifying light that checks plugs an seen little shiny aluminum flakes. We took it off the dyno yesterday and the bearings was all shiny. He said that the detonation was hammering the bearings.
what was your PTV clearance? Who built the engine?
Something went wrong... something wasnt right for that kind of damage.
My 5.3 is making power in that neighborhood on 30 degrees total. Its seen 38 degrees total and no speckling or detonation that i could see
Something went wrong... something wasnt right for that kind of damage.
My 5.3 is making power in that neighborhood on 30 degrees total. Its seen 38 degrees total and no speckling or detonation that i could see
I stroked a 6.0 to a 414ci. It has an eagle rotating assembly. It has a 4in stroke, h-beam rods, an -4cc flat top piston. We put it on the engine dyno last weekend and number 1 piston was destroyed. Busted the block. Gave the head hell. The dyno guy said it was detonation. It has a 850 holley carb, holley single plane intake, and a MSD LS. The first two pulls it made 540 hp with 24 degrees of timing. The third and finally destroyed pull was at 28 degrees of time and made 560. He checked the brake pacific on the second pull and said it was rich enough. My question is has anyone has this setup and what timing are you running. All the pulls was done on 100 octane avgas. I can't believe that detonation killed it and that quick.
What heads and CC chambers do you have?
100LL AV gas is going to leave speckling but not metal speckling.
AV gas burns real dry and anyone running that stuff has better be spiking it with a oil such a Marvel Mystery oil. I have heard of instances of it siezing valves in the guides.
At 11.5 to 1 you should be fine with 93 octane pump fuel. However if you have a set of 59 or under CC heads you could be as high as 12.5 to 1.
It's really hard to believe you busted a hole in the block with a forged piston because they don't shatter (unlike hyper). Most of them you can beat with a hammer into a ball. That seems like maybe the ring gap was messed up and maybe you broke the piston top somehow.
What jets were in your 850? Power valve's? Heads messed up bad? Valves bent?
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It has the ls3 headsthat was ported. It has comp cam aluminum 1.7 rockers. Texas speed 650 dual valve springs and harden push rods. Compcam 235/240 @50 621lift 112 lsa. The carb we found had 72s front and back , so thats a little lean what was told to me. It was calculated at 11to 1 compression
Last edited by boostedbu67; Feb 6, 2016 at 03:52 PM. Reason: add more info
It has the ls3 headsthat was ported. It has comp cam aluminum 1.7 rockers. Texas speed 650 dual valve springs and harden push rods. Compcam 235/240 @50 621lift 112 lsa. The carb we found had 72s front and back , so thats a little lean what was told to me. It was calculated at 11to 1 compression
You had something else happen.
Yep. Something was not right with that engine. You had very little timing and the power it was making was pretty low. I could only speculate what it might be with such limited info. As stunningman said, that motor should be fine on pump gas; assuming that camshaft was installed on a 110 intake centerline.
I stroked a 6.0 to a 414ci. It has an eagle rotating assembly. It has a 4in stroke, h-beam rods, an -4cc flat top piston. We put it on the engine dyno last weekend and number 1 piston was destroyed. Busted the block. Gave the head hell. The dyno guy said it was detonation. It has a 850 holley carb, holley single plane intake, and a MSD LS. The first two pulls it made 540 hp with 24 degrees of timing. The third and finally destroyed pull was at 28 degrees of time and made 560. He checked the brake pacific on the second pull and said it was rich enough. My question is has anyone has this setup and what timing are you running. All the pulls was done on 100 octane avgas. I can't believe that detonation killed it and that quick.
The first pull at 24 degrees it had an intermittent miss at 5000rpm. We checked all the connection and made another pull with the same results. We went to a colder plugs and the next pull we went up to 28 degrees. He took a look at the first set of plugs with a magnifying light that checks plugs an seen little shiny aluminum flakes. We took it off the dyno yesterday and the bearings was all shiny. He said that the detonation was hammering the bearings.
It has the ls3 headsthat was ported. It has comp cam aluminum 1.7 rockers. Texas speed 650 dual valve springs and harden push rods. Compcam 235/240 @50 621lift 112 lsa. The carb we found had 72s front and back , so thats a little lean what was told to me. It was calculated at 11to 1 compression
What a mess. Maybe the 650 springs need replaced with something in the 700 range to give yourself some margin there. Check with a cam expert most springs are rated with stock rockers I believe which weigh less over the valve. Check the reluctor clocking just as a preventative measure to make sure it's where it should be. IMO you definitely had detonation and most likely due to the lean condition. I would jet the carb 87 square with no power valves for your next venture and tune from there. Better rich than lean as you now know.
Leave the AV gas at the airport.