So what was the kaboom? Detonation? You're running 100% methanol, right? If so, did that ignite in the intake tract somewhere, and that's what caused your hoses to blow off? That really sucks to hear. I've been following so many different build threads I didn't realize you were running 14psi. That's quite a bit of boost for an engine originally designed to be NA.

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BKR7E plugs were in for 10-15 miles total. My wideband said ~14.7 while cruising. I didn't notice what AFR it went to during that WOT pull. All plugs are white. Every plug I've pulled before this set have been proper tan color.

Before I started pulling stuff I used my stethescope and couldn't pinpoint the noise. It sounds like under the intake manifold. I pulled the plug wires on the driver side and couldn't make it stop. Truck started right up, ran and idled like a champ. CLACK CLACK CLACK CLACK CLACK CLACK CLACK CLACK :-(






I don't know if these pics are in order but everything looks good to me. I can't find anything visually wrong. I cranked the motor over and can't hear the noise. I can see down the intake runners to the top of the valves. Everything looks good to my eye.

Open to suggestions at this point. Next logical step seems like pulling the heads.

 

100% methanol at ~1200cc/min. It has been running excellent at 14psi other than going thru spark plugs every 3k miles! This motor is a stout sucker. I think that's exactly what happened. With that much meth being sprayed, and the engine misfiring a few times it built up. I mean it was BAANNGG! So, question is, what did that damage when that occurred?

 

This isn't encouraging. This is my identical noise. http://www.expeditionportal.com/foru...E-Engine-Noise Time to pull the oil pan, or just start looking for a doner/rebuild/JDM. Or a 4.0-4.7 swap hmmmmmm

 

I wouldn't have thought that tapping noise in the second video wa a rod bearing completely gone. But sometime listening to videos isn't a good representation of the real sound, since cameras don't have good mic's they can miss a lot of the deeper sounds that a rod makes, and make it sound like a higher pitched, lighter tappier valve train issue.

If it's a rod bearing, you should have all sorts of shininess in the oil pan.

The usual ping ping boom boosted engine failure is hardest on the pistons, perhaps it's a piston missing a chunk. But a detonation under a lot of boost is basically like hitting the piston top with a sledgehammer, it's a crapshoot what fails - piston crown, top ring/ringland, rod, rod bearing.

I wouldn't throw in the towel, this is just part of the learning curve. Either stick another stock junkyard shortblock in and keep rocking (try to figure out what happened - do you have any logging capabilities?), or ponder doing up something a little stronger - lower compression forged pistons and H-beams, and start rocking it even harder.

 

14psi is nothing actually, particularly with meth. The real limiting factor is the stock ECU, it just doesn't know how to manage what it is seeing and can lead to things like this.

I personally would not be afraid to run 18-20psi+ with a large shot of meth and a way to tune the truck. On the stock ECU 14psi is a good number.

My best guess is that the stock ECU saw something it didn't like (from the MAF sensor maxing out to a knock event) and retarded timing or possibly even cut fuel. Thus leading to the backfire and/or melting a valve.

Sucks to see the issue, might be time to look into some form of tuning option. A cheap fix is something like an AEM FIC. While far from perfect it is a heck of a lot better then nothing.

The best option is a full standalone.

 

Thanks for eveyone's input. I'm not actually that discouraged. I feel like what happened was not out of line for what I do with that motor.

Considerations at this point are most likely a junkyard shortblock, and slightly lower boost until I get some kind of timing control. Also my Holset is pushing oil into the intake and exhaust, and it's been getting worse, so I have do something there too.

Hey Ace, while the motor's out, be a good time to get that converter restalled, eh? :-)

 

Yeah, just get a shortblock, don't mess with fixing it IMO as it will most likely cost about the same all said and done and even then might not fix it.

Also give you some extra parts for any future issues.

Not to mention like you said you can install the converter while in there.

I would put some kind of ECU at the top of the to do list after it is running again. The turbo spitting oil could also have played a role in this, it tends to make the engine much more knock prone and likes to cause backfires.

 

I'm betting on a combination of things. Stupid me didn't reset the autolearn box after changing nozzles the other day (probably not a big issue, put in slightly larger nozzle to try to get a 11.5 AFR WOT), turbo was pushing large amounts of oil in both directions (even though it was supposed to have been rebuilt when I got it) and the MAF was immediately after a 90* silicone coupler. I was asking for it.

 

I think it would be hard to tell without taking the heads off. It sounds like a floated valve. I'll bet an intake valve didn't have a chance to close up completely and ignition leached through the intake and detonated all of the meth (another reason I don't like meth injection as opposed to bigger fuel injectors and an intercooler) and damaged a spring or valve/seat.

I'm personally in the near future going to buy a spare engine and build it from the ground up with all moly forged internals and heavy duty metal gaskets. My current engine won't see any more than 8 psi until then.

Get your heads off though man

 

Well aren't you an optimistic SOB! I will yank the heads later today I hope and report back. It does seem as if the scenario went: the ignition misfired a few times, meth pooled up, then ignited.

 

The chances of meth backfiring are EXTREMELY small. Most methanol powered drag cars use mechanical injection, which is basically meth injection on a massive scale and not as good in many ways. They hardly ever have backfires.

Mostly due to the fact that methanol is extremely hard to ignite. Which is why it makes such a great fuel for high performance applications.

Not to mention that every carb engine of the 80's and earlier had a far greater risk of backfires then meth injection.

Lastly if backfires are actually a concern then simply run a 50/50 mix of water/meth. It is not flammable and thus impossible for it to backfire.

I see no reason to build the 5vz until well over 400whp. It has shown to handle that with FAR FAR from optional tuning options.

I would put the money for a build instead into a standalone ECU. Much better use of the funds IMO as a bad tune will kill a built engine just as it will a stocker.

Properly tuned I see no reason the stock engine could not handle 500whp+. Heck far worse engines then this do that all the time.

 

Lol optimistic indeed. This is a 5vz we're talking about man!

 

If a valve doesn't close in time and the combustion leaks into the intake, there's not much pure methanol can help. Hell, these type of detonations happen with nitrous oxide all the time and it isn't even flammable at all.
Another thing is the MAF is seeing a lot of heat being fed air through non intercooled plastic pipe. The MAF isn't telling the ECU that IATs are way lower than the air is at the sensor

 

Right but that should only happen in the case of a failure such as this. When working properly the combustion gasses should never enter the intake.

Also nitrous only backfires if it is a wetshot. A dry shot (aka, no fuel being jetted) doesn't have the backfire issue.

The MAF does read IAT's but most likely they are outside the sensor range or at least the ECU's tuned range.

 

Hear, hear!

You do get a few more pings before the boom with forged pistons and h-beams, but the end result is about the same, a complete teardown and rebuild.

You might get to keep the block and crank with the $$$$ internals though.

But yeah, tuning mistakes kill engines, you have to try really hard to actually break the engine from too much HP. It's usually some detonation you couldn't detect that blew it up well before it should have died.

 

Love the feedback and discussion dudes. Yall are awesome. I'm learning so much- albeit some of it by trail and error.

 

Got the heads off and I can't see any obvious damage to the heads. Everything looks great, actually. The valves, tops of the pistons, cylinder walls look good. Everything is appropriately colored which I guess means it's been running in good tune, until this.

My only "DOH" moment of the night was turning the passenger head upside down and all the shim buckets fell out on the floor. That's gonna suck to get those adjusted correctly again, assuming I reuse the heads.

 

By chance there is nothing in any of the intake tracks is there? With a backfire like that who knows what might have come loose and got sucked in.

 

Take off the pan next, I guess.

Do you need a working OBD2 port on the thing to keep a license plate on it? I'm really not sure how OBD2 cars work with standalone injection systems.

There are plenty of choices in standalones, I've been using Megasquirt since 2006, the wagon now has an MS3X on it which has pretty much all the inputs and outputs you're likely to need, all wired up and ready to go (the harness pigtails are well worth the money - individually lettered wires are far easier to deal with than studying pinout diagrams and adding wires to plugs). MAP tuning is probably a bit easier to tune than MAF is, plus it doesn't matter if you have a BOV/CBV, or if you have some air leaks, and you're not trying to keep a MAF working properly in situations it wasn't designed for. That and a good wideband O2 sensor.