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The power of detonations...?

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The power of detonations...?

Postby SWR » Tue Jun 04, 2013 1:40 pm

Friend of mine had a catastrophic engine failure a week ago. Cast iron block, inline 4. All 5 1.5" thick lower mains and the 1" thick cast alu girdle bolted to them snapped completely in half. They say detonations as there's a small portion of area on the squish pad on the intake side of the pistons showing some pockmarks. NO pinched rings, no cracked ringlands, no bent rods or banana-shaped wrist pins, yet the crank broke all the cast iron mains and the girdle below them in half, dropping the crank so much it had a 3mm / 1/8" mains clearance - spinning the bearings in the process - when disassembled?

Anyone seen anything like that? Or can you come up with a more likely explanation? Turbo, E85, just 20 psi of boost, it saw almost 30 on the dyno weekend before, no issues. Engine ran flawlessly for 2 hours of 1st and 2nd gear trashing about at WOT with customers of his main sponsor on board one weekend, then 12 minutes combined of 3rd gear track use the next weekend and kaboom goes the whole bottom end. Spark plugs look melted / cracked, cylinder sleeves have sunk about 0.1mm into the block too, but no sign of steam when the engine grenaded, so hydrolocking sounds unlikely. Atleast to me... Mains clearance seems to have been a fair bit on the wide side, though, it seems like std. main bearings in a 1st. US ground crank... pointers please, while I still have hair.. ](*,)
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Re: The power of detonations...?

Postby lorax » Tue Jun 04, 2013 1:58 pm

SWR wrote:Friend of mine had a catastrophic engine failure a week ago. Cast iron block, inline 4. All 5 1.5" thick lower mains and the 1" thick cast alu girdle bolted to them snapped completely in half. They say detonations as there's a small portion of area on the squish pad on the intake side of the pistons showing some pockmarks. NO pinched rings, no cracked ringlands, no bent rods or banana-shaped wrist pins, yet the crank broke all the cast iron mains and the girdle below them in half, dropping the crank so much it had a 3mm / 1/8" mains clearance - spinning the bearings in the process - when disassembled?

Anyone seen anything like that? Or can you come up with a more likely explanation? Turbo, E85, just 20 psi of boost, it saw almost 30 on the dyno weekend before, no issues. Engine ran flawlessly for 2 hours of 1st and 2nd gear trashing about at WOT with customers of his main sponsor on board one weekend, then 12 minutes combined of 3rd gear track use the next weekend and kaboom goes the whole bottom end. Spark plugs look melted / cracked, cylinder sleeves have sunk about 0.1mm into the block too, but no sign of steam when the engine grenaded, so hydrolocking sounds unlikely. Atleast to me... Mains clearance seems to have been a fair bit on the wide side, though, it seems like std. main bearings in a 1st. US ground crank... pointers please, while I still have hair.. ](*,)



Detonation caused by some dumbass putting used motor oil in the fuel jug. METHANOL!
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Re: The power of detonations...?

Postby Tuner » Tue Jun 04, 2013 2:40 pm

A spark plug heat range which could tolerate intermittent short duration WOT could be way too hot for sustained WOT. What was the plug heat range? The melted plugs suggest pre-ignition. The alcohols are more sensitive to pre-ignition than gasoline. When spark plug parts or some other hot spot is glowing red, pre-ignition advances with each firing cycle and can occur 90° or more before TDC, so it isn’t hard to imaging detonation will occur and be very severe. Assuming no failure or shortcoming of the cooling system occurred, perhaps less spark advance or an internal coolant, water or water-methanol, could have prevented this.
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Re: The power of detonations...?

Postby Belgian1979 » Tue Jun 04, 2013 2:40 pm

Jesus ! :shock:
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Re: The power of detonations...?

Postby Tuner » Tue Jun 04, 2013 2:47 pm

lorax wrote:
Detonation caused by some dumbass putting used motor oil in the fuel jug. METHANOL!
Image

That kind of block damage is seen in 302 Fords used in road racing, such as SCCA American Sedan class. To me, it seems people are slow to learn Fords don’t require as much timing as Chevys and they particularly don’t tolerate it in the lower end of the RPM range.
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Re: The power of detonations...?

Postby SWR » Tue Jun 04, 2013 2:47 pm

This is his, not quite a methanol one but a show stopper nonetheless..
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Re: The power of detonations...?

Postby SWR » Tue Jun 04, 2013 2:57 pm

Tuner wrote:A spark plug heat range which could tolerate intermittent short duration WOT could be way too hot for sustained WOT. What was the plug heat range? The melted plugs suggest pre-ignition. The alcohols are more sensitive to pre-ignition than gasoline. When spark plug parts or some other hot spot is glowing red, pre-ignition advances with each firing cycle and can occur 90° or more before TDC, so it isn’t hard to imaging detonation will occur and be very severe. Assuming no failure or shortcoming of the cooling system occurred, perhaps less spark advance or an internal coolant, water or water-methanol, could have prevented this.

I am aware of this, and the spark plugs they say they used was the second coldest plugs they could find for this motor. I always contour any sharp edges and run the coldest plugs I can make it idle with. Their combustion chamber was stock, though, I always remove the section where they had the pockmarks. But what makes me wonder is the effects on the pistons... I have had massive preignition in an E85 engine before - one cylinder, bad intake distribution - and that piston top was just melted. I see NO melts on these pistons, at all. Just tiny det-marks on the intake side..
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Re: The power of detonations...?

Postby lorax » Tue Jun 04, 2013 3:03 pm

Tuner wrote:
lorax wrote:
Detonation caused by some dumbass putting used motor oil in the fuel jug. METHANOL!
Image

That kind of block damage is seen in 302 Fords used in road racing, such as SCCA American Sedan class. To me, it seems people are slow to learn Fords don’t require as much timing as Chevys and they particularly don’t tolerate it in the lower end of the RPM range.

This particular engine was a blown BBC on meth. But it proves just how much oil in the combustion chamber can effect the octane of a fuel, even methanol.
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Re: The power of detonations...?

Postby Tuner » Tue Jun 04, 2013 3:05 pm

The melted plugs suggest pre-ignition. It could have advanced into severe detonation so quickly the machinery broke before it had a chance to melt.
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Re: The power of detonations...?

Postby Barbapapa » Tue Jun 04, 2013 3:24 pm

The sleeves sunk? Do you think ALL of those things somehow happened at once? How are (were) the sleeves sitting in the block?
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Re: The power of detonations...?

Postby MELWAY » Tue Jun 04, 2013 3:41 pm

I ve got a 355 chev 010 4 bolt dyno mule engine with 13.1 comp and makes about 600HP...
I have done over 200 dyno pulls and 200 1/4mile passes on it...

One day i decided to pull a few deg timing and run it on pump gas,,,with in 3 pulls it lost a chunk of power...

Pulled the pan to inspect bearings and found 2 broken bearing caps,,,just like what you are seeing..
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Re: The power of detonations...?

Postby SWR » Tue Jun 04, 2013 3:56 pm

Tuner wrote:The melted plugs suggest pre-ignition. It could have advanced into severe detonation so quickly the machinery broke before it had a chance to melt.

True, the other grenaded engine took out a piston and a cylinder wall in about a millisecond. Heard no knock then, and on the engine here they said they heard nothing either, it just started vibrating badly. No wonder preignition is known as the "silent killer"...
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Re: The power of detonations...?

Postby SWR » Tue Jun 04, 2013 4:05 pm

Barbapapa wrote:The sleeves sunk? Do you think ALL of those things somehow happened at once? How are (were) the sleeves sitting in the block?

They had issues with badly machined sleeve bores, so the engine has dropped the sleeves 3 times already, even if the block was heated a fair bit and left overnight to cool slowly with the sleeves under a fair bit of pressure the second time. So I guess that sleeve drop happened at the "same" time, i.e. when the engine was loaded in the higher gears they sunk again. I did not do any machine work on this engine so I really have no idea exactly how they did it, I just was told it was a botch job the first time, and they tried rectifying it after. But the block had sunken liners when they brought it to me now..
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Re: The power of detonations...?

Postby kirkwoodken » Tue Jun 04, 2013 5:11 pm

MSD rev limiter dropping sparks causing detonation?
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Re: The power of detonations...?

Postby BrazilianZ28Camaro » Tue Jun 04, 2013 5:42 pm

Melted plugs ...looks like this engine had a fuel delivery problem and was way lean overheating everything,, plugs were incandescent = pre ignition.
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