Kaboom! Another one down

[RED09GT]

What makes you say that about the intake manifold gaskets leaking? I'd think that if that was the case, that cylinder would have been bleeding boost and less likely to detonate. I'll wait until I get it all apart before speculating too much.
It may have just been a fluke between losing traction, jumping off the throttle, getting back on it, hitting the rev limiter, then the WOT box cutting ignition as I shifted to third, etc... A lot went wrong in that second.
It was also about 95 degrees that day as well so that didn't help.

Datalogs showed no issues and the last one I did was a few days before this happened so I don't think it was tune related.

 

[Rick Simons]

There are a lot of aluminum engines running around out there that use a nickel-silicon-carbide coating that's electro-plated on. It's very hard, very durable, and has a very low coefficient of friction. Not to mention the obvious weight savings over a steel or iron liner. Our 2-stroke race bikes used this coating. On the unfortunate occasion where we would have a piston seizure, we could usually clean off the smeared-on aluminum with muriatic acid, drop n a new piston, and go to the grid. In severe cases the cylinder would have to be stripped of the nikasil coating, repaired, then recoated and honed to size with a diamond-faced hone. Sorry about getting off topic. Almost forgot; if you see little balls of aluminum on anything, that's a sure sign of detonation, which can also blow spark plug insulators apart.

 

[Rick Simons]

From the photo it looked like there wasn't much contact between the gasket and the head- the "clean" area where the gasket touches is pretty small. My apologies, I forgot for the moment the engine is boosted.

 

[RED09GT]

Maybe you were looking at the other photos? Mine are the two not so clear ones with the borescope inside the cylinder.

 

[RED09GT]

Partial teardown,
#8 Cylinder
Definitely some abnormal combustion, LOL. You can see the slag from the piston welded onto the cylinder liner. The head has a few knicks but nothing that can't be cleaned up. Some debris from the spark plug migrated over to cylinder #4 and left a couple dings in that piston as well-that cylinder wall is unscathed. Going to pull the bottom end apart this afternoon.

The head gasket and TTY hardware showed no signs of lifting or failure of any kind so I will continue to use TTY.

Some small PTV contact marks on all the pistons so the valves did float during that series of events. I'm leak testing the heads and so far, things are staying dry.

 

[Juice]

That piston damage did not happen when it revved to 7k. That piston has been deteriorating for some time. Need to adjust tune after you fix the engine.

#8 cylinder in Fords seem to be the 'weakest'. Thats the one I broke on my pushrod 5.0, and thats the one some tuners pull timing on in coyotes. I have not implemented #8 protection in mine yet.

 

[Dino Dino Bambino]

The no.8 cylinder tends to run the hottest in Ford V8s 'cause it's the furthest away from the water pump. The problem is compounded on the Coyote 'cause it has two exhaust valves per cylinder and, as a result, there's less room in the head to make the coolant passages big enough to cool the exhaust valves.
The MMR head cooling mod partially resolves this issue:

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&products_id=555

 

[RED09GT]

It wasn't from revving that high, it was from the big ass pop that happened at that point.

This looks like one big bad pop to me.

 

[xeninworx]

Ouch

 

[crjackson]

The MMR head cooling mod partially resolves this issue:

http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&products_id=555

Do you really think this kit offers any meaningful protection? It’s an interesting idea, but I’m not sure of it’s effectiveness. I’ve yet to hear anyone (except MMR) singing it’s praises.

 

[Dino Dino Bambino]

I know Brenspeed recommend it with their forced induction upgrades but I'm not so convinced.
Basically it diverts coolant from the back of the passenger side head (cylinder 4) to cylinder 8. While it may reduce the difference in cylinder temperatures, I think it's just a band aid. Perhaps a better solution might be to somehow get lower temperature coolant supplied to cylinder 8 directly from the water pump with a bypass.

 

[RED09GT]

I'm thinking direct port meth or seeing if I can buy barrels of ethanol and start mixing my own E30 since it isn't readily available in almost all of Canada (2 stations, closest one to me is further away than I can travel on a full tank of E85-or even 94 octane pump)
Cylinders 1, 2, 5, and 6 were really clean. This tells me that a lot more meth made it to the front cylinders. 3, 4, and 7 had the most carbon by far. Distribution is a big problem with these long runner intakes.

 

[Pentalab]

What is your rev limiter set to?

 

[RED09GT]

I think it was 7200.
I wish I was datalogging so that I could tell what exactly I did.
I had my dragy out and was trying to make a run. For the best that I can recall, I pedaled my way through first, eased my way into it in 2nd, flat footed it at about 5000 rpm, spun around 6200, it zinged past 7K before I got off it and tagged the limiter.
I then put my foot back on the floor, heard a loud pop, and upshifted (wot box, so no lift) into 3rd and stayed in it. I could feel that the car had lost a fair bit of power, looked in the mirror to see a big cloud of black smoke behind me, let off as I went into 4th and then the check engine light flashed.

I then stopped, checked under the car, no oildown. Started it back up and it rattled but still idled and ran somewhat. Tried driving it and it was way down on power to even get moving. Towed it back to my friend's place.

My theory is that the combination of it being a hot day (35°C), the ignition cut from the RV limiter so there was excess fuel and getting back on it caused it to detonate. The detonation also appears to have occurred between the top ring gap and the second ring.
Oh well, learn from it and move on.

 

[Midlife Crises]

I'm thinking direct port meth

This makes sense to me. I don’t believe the manifolds are designed to carry atomized fluids or to keep them in suspension. They just pass air in a certain velocity range.

 

[Midlife Crises]

excess fuel

Detonate from excess fuel?

 

[RED09GT]

Detonate from excess fuel?

Not so much excess as residual. In this case the ignition occurred in an area of the cylinder that fuel wouldn't normally be.
In proper combustion, the air fuel charge goes in towards the center of the cylinder, spark plug ignites it, and the flame front travels to the far end of the cylinder and burns the rest as the piston goes down. In this case there was a bit of fuel on the wall at the back side of the direction of the flame front, likely from when the Rev limiter was hit that didn't burn previously. Not enough to quench combustion but just enough for a lean detonation.

Either way, this wasn't your simple bad tune detonation. This was a driver mistake or possibly an octane issue as it ran very well for a year and a half. Only change I made since the tune was done was to go to a bigger air filter as the one I had on it was way small and choking the airflow.

 

[Midlife Crises]

I think detonation burned away the top land and allowed the explosion to move into the narrow, weaker ring grooves and ka-blewey. Same result.

 

[RED09GT]

I'm just glad that the piston failed the way it did and relieved pressure rather than hammer the crankshaft and the rod.
I've got the whole off season to decide whether to do one sleeve or to sleeve the whole block and go big bore. One of my friends-who is a machinist spoke about distortion in the adjacent cylinder when sleeving a single cylinder. He mostly does stock replacement stuff rather than performance stuff so I'll see what the shop that I usually use has to say.

With the border closed, the difference in cost between a boss block and shipping it to Canada vs. shipping a set of sleeves and the machine work makes sleeving the more cost effective option.

 

[Midlife Crises]

How about a block from a wrecking yard motor? I have no idea what that would cost in Canada.