Head gasket shot. Side closest to the camera is the block side, far side is head side.

 

Head side of gasket, top of piston ( lightly cleaned with brake cleaner ) and also plug from that cylinder. Plugs were actually only new about 20-30 miles previous, and with about 1-2 miles of running after the blow up so probably dont mean much. TBH I'd have thought it would look worse all things considered.

 

Just a thought, how tight was your earth ground that you stated has always been there? Maybe the motor mount let loose and the torque from the engine / strap broke it. Or possibly someone cracked the head with too long of a bolt in that location?

Tim

 

Piston from all sides. Bit of scuffing at top although that isnt out of the ordinary for others I've had. Rings are all ok, moving freely etc

 

Impossible. Usually a short stubby 17mm spanner to tighten as it's in an awkward spot. Engine is bolted solid into the car anyway and earth strap has plenty of length.

The burn in the middle of the chamber is probably the key here. It may just be the HG let go there and the subsequent events were unlucky on a large scale.

 

Hi Steve, good D-Logger graphs.
When this happened it was FAST not over the passing of time.

One guess is that the Head Studs (steel) did not stretch to match the AL Crankcase/Head expansion rate.
This can cause the HG to be "extruded" and thus damaged.
This effect could allow the studs clamping force to be different across the deck.

I have had experience learned from BDA/Kent engines Canadian/Atlantic racing.
My friend Mike Costin created the Belt Drive type A head conversion for the Ford 1600 engine.
A similar problem with head gasket failure/head cracking was found in the first races.
The "cure" was to undercut the head studs/bolts to ALLOW stretch that MATCHED the AL head casting expansion.

I ALSO find it ODD that ARP offers "undercut" studs for use in racing engine though not for LS bases engines ?

AGAIN, I state ONLY a guess at the cause.

Lance

 

The head failed. Could be because of a warped block deck or head prior to torqueing.
Could have also been a poorly formed head casting with cracks starting and ultimately failing enough to flood the cylinder then bend the rod and blow off the already compromised head corner section. It's just aluminum.

 

Stevie, thanks for the PM. We spoke with our Greg Changet who's been working on this with you. We also spoke to Mike Schmidt who's helped you in the past. Mike's idea was this:

"I remember repairing those for him when I was at TEA 6-8 years ago. Torched a couple of cylinders to outside IIRC. My guess is something in that corner of the block or head was warped or was not parallel or flat. The corner of the head was stressed and cracked when it was torqued then broke off off once the cylinder pressure hit it.

There was mention of a liner being replaced is it slightly proud of the deck? I’ve seen wire o-rings and improper receiver groove depths and liners that are too far above the deck cause a crack through the spark plug holes and corner to crack off like in the pictures. That was mostly on sb Fords but still a similar 10 head bolt design.

I would definitely have the block checked for flatness and possibly hardness as it may be annealed (that far corner could have gotten hot) before you bolt another head on it. "

When heads are welded, it creates a line where hardness differs. When the cylinder hydraulic'd, something had to give and the crack started from the outside going in along this line.

As for the basic cause...if there weren't other changes to the tune etc...we sometimes see fuel quality or age as being a problem when something was fine one moment...but not the next.

At this point, it probably doesn't make sense to send the heads back again. They've been through the wringer and it's best to start fresh.

 

Also, on the pistons...it looks like the engine got hot. When the piston ring cant dissipate heat into the water jackets, the top land expands and scuffs. The top ring land is usually about .055" from the bore on forged pistons, but they are often opened up to .065" for boosted applications. When the piston ring cant dissipate heat into the bore, the top land expands and scuffs. That set of pistons should be replaced when they get to that stage. Let us know what you find when you measure the top land diameters on the other pistons.

 

Edited lol

 

The head or block was not warped at any time.

My talk of liners was in relation to potential repairs as I had honestly expected the block to be damaged. But this doesnt seem to be the case.

The block/liners are fine , all standard LS2 +0.005"

That same head was indeed repaired 10 years ago and Mike did deal with that, cylinder 6 blew out on a standing mile run. Although it blew on the solid metal as opposed to through a waterway. It took out the head and block at that time...along with pretty much the rest of the engine lol. Given other stuff that occurred that day, I should never have raced, but saying no is difficult when so close to a certain goal ( which was 200mph back when that failed ) But that repair has been 100% and I do not believe in any way it has contributed to what happened here. Nor was it anywhere where the head cracked now.

It is primarily a pump fuel build, so yes it does get hot in there although I do use pump+meth when racing.
Obviously I cannot comment on localised temperatures around the block, but the engine is never run with high water temperatures.

As I was due to a 1/2 mile event on Saturday I had been doing a little testing to ensure everything was ok running with the meth as everywhere else I just use pump only. And apart from a couple of hiccups, all was running fine. Whether those hiccups were a precursor to what happened or unrelated, I dont know. But TBH they were a little unusual for this car, which mostly runs pretty faultlessly.

So yes the scuffing is there on the top of the piston and probably not ideal or pretty....it genuinely doesnt concern me. The same pistons have been in there for 3 years or so, so have done a reasonable amount of work....and it seems survived this unscathed which is more impressive.

Obviously the major damage was the water in the cylinder allowing full force into the head....it's just what let go to allow the water in there in the first place. And it maybe is just as simple as unfortunate head gasket/clamp failure ? Which then torched through as can happen with MLS...and bang lol.

 

Just to add a little detail from 2008 when I bust it then as the head repair has been mentioned etc...This was 100% my own fault, I had issues on the day, the alternator had failed but as I was so close to hitting 200mph in the mile...I kept on racing. Even more frustrating to find out they had shortened it to 7/8' mile because apparently rabbits had eaten through their cables overnight and had to shorten it. So I ended up with 198mph over that distance and a fucked engine lol

All of these pictures in this post are from 2008 and in no way related to what has happened this week. Other than them both being cool carnage, unfortunately at my expense lol
But whilst there was HG failure in 2008, everything was wrong because of the low battery voltage and it was just idiotic to continue racing so not a bit of wonder things did fail, and perhaps more impressive they hung together as long as they did.

Even more strangely the cylinder with the piston that got fucked the most wasnt even the one that blew out.