Opened engine to find my worst nightmare... advice needed.

[Arith2]

It looks very possible there was detonation, and reasonable knock values would have stopped that.

I did also have an engine blow with the B Spec tune. That engine wasn't in the great condition but the piston EXPLODED! I'm starting to become a skeptic.

[heinzboehmer]

It looks very possible there was detonation, and reasonable knock values would have stopped that.

Makes sense.

[SteelGreyM]

It won't end up being cheaper once all the labor/parts are paid for, it won't have a power benefit, and it is more likely to have issues.

After doing all the math it turns out it will be cheaper actually because I will be doing all the labor myself.

Just got off the phone with Andrew at Lang ring to get his professional opinion. He suggested I get my block bored out slightly, upgrade to slightly oversized pistons that come with new rings (CP forged. Its the one they use all the time in their builds.) My rods and crank are fine so keep that. After that just go with OEM rod bearings and king main bearings (clearances checked of course). He also said that while my head may be salvageable, its not worth the time and money to find out and that I should just get a new one.

Doing this would negate the price I would pay for a fresh block (that may end up having problems!) and used pistons.

I know this is probably not the smartest and most reliable idea but im confident that this can turn out okay. Something inside is telling me to just go through with this plan.

[Obioban]

Why do you suggest choice one? Im certainly going back to stock tune and getting rid of the e85 setup. I havent had or heard of issues with headers so ill keep my headers.

What potential complications would there be from doing choice 2 as long as all clearances are accounted for?

It won't end up being cheaper once all the labor/parts are paid for, it won't have a power benefit, and it is more likely to have issues.

[Obioban]

Another vote for choice 1. Obioban any particular reason why you're implying the tune caused this?

It looks very possible there was detonation, and reasonable knock values would have stopped that.

[SteelGreyM]

I’d say do choice 1 and go back to a stock tune to not repeat your experience.

Why do you suggest choice one? Im certainly going back to stock tune and getting rid of the e85 setup. I havent had or heard of issues with headers so ill keep my headers.

What potential complications would there be from doing choice 2 as long as all clearances are accounted for?

Another vote for choice 1. Obioban any particular reason why you're implying the tune caused this?

I think he is saying that to eliminate any potential factors that have may caused this.

[heinzboehmer]

Another vote for choice 1. Obioban any particular reason why you're implying the tune caused this?

[Obioban]

I’d say do choice 1 and go back to a stock tune to not repeat your experience.

[SteelGreyM]

Unless the tune turned them down, the knock sensors should protect the engine from detonation.

OP: what tune are you running?

Unrelated: I think you'll end up regretting fixing this engine instead of buying a used one.

I just have the build journal B-spec tune. It's worth noting that I had an e85 flex fuel kit. I never ran more than e65 and I never ran more than maybe 15 tanks of the stuff.

Before I sent build journal my file for the b-spec tune they made me scan my car with a BMW scanner and we found out one or more of my knock sensors was bad. I replaced all of them with new OEM. IIRC this was well before I started noticing any of these symptoms.

And yea ive decided against repairing this engine. Could I get it running? sure. Would I *really* be comfortable with it? Hell no.

Im going back and forth between 2 choices at the moment.

Choice 1: Just get a used, ~120k mile engine and slap that bad boy in after doing rod bearings and transferring my VANOS.

Choice 2: Get a good used block and pistons and rehone the block (NOT bore). Transfer my crank and replace rod and main bearings with OEM. Replace the piston rings with OEM. Replace head gasket with OEM. For the head, i'm gonna call up lang racing and get their opinion on it. Worst case scenario I buy a used good head. After that, all damaged pieces are repaired. Id basically have a brand new engine minus the pistons and block. I dont plan on running any boost so perhaps this is the way to go...

The only thing stopping me from doing choice 2 is the possibility that i'll mess something up somehow. But I have done tons of research and every other job ive done on this car has been a success because of the hours of research I do to make sure things go right. Id imagine as long as I triple check all my clearances I should be good.

[Syfon]

This might be a silly question but how would you guys recommend removing my block? The head and the engine lifting bracket is off the car...

I was thinking just pull the front end off and slide it out with the trans right? Since there is no support bracket up top should I like... tie ratchet traps around my engine and into the crane hook?

I removed the engine/trans in my garage. Disassembled the entire front end and pulled the engine trans as one then broke them apart and started the process of tearing down the s54. Was a lengthy job and fun to see it all in pieces lol

[Syfon]

If you want to keep the same motor, that's a full tear down and rebuild. No way around it.

Of course the other option is to find a cheap s54, do the bearings/vanos and any other items needed then put it in your m3 and part out your current motor.

[Obioban]

Unless the tune turned them down, the knock sensors should protect the engine from detonation.

OP: what tune are you running?

Unrelated: I think you'll end up regretting fixing this engine instead of buying a used one.

[Papermaker]

Bring the thread back to detonation, from memory I think the technical definition of detonation is the uneven ending of combustion gases, meaning the outside edges of the combustion chamber gases are heated above the stable temperature of the air/fuel (A/F) mixture. The mixture forms free radicals that are unstable and start to burn explosively. When the frame fronts ignite, they travel across the combustion chamber and meet somewhere near the middle causing a violent release of energy. The ping or knock you hear is the sound of the flame fronts meeting. As they meet, they tear pieces of the combustion chamber and piston crown from their surfaces. The force is also transferred to the rod, crank and block.

In the seventies my father owned a 1968 Pontiac Grand Prix with a 428 ci engine. It detonated all the time regardless of the fuel octane or ignition timing. It didn't seem to bother the engine as far as I could tell. The engine designs in those days were so heavy they were inadvertently strong enough to withstand the harmful effects of detonation. In the light aircraft world Lycoming and Continental and other similar AC engine designs were built to power the AC only, not to withstand detonation. 30 seconds of detonation in one of these engines usually required complete disassembly and inspection. So, the answer about rod, crank and block damage is it depends. What to BMW dealer shops and M3 race teams do when the engines suffer detonation?

Okay, with limited information I'll take a guess about why you had detonation. Remember when the head gasket failed both combustion chambers shared their chambers with each other. During the intake stroke of the cylinder was drawing mixture through the intake valve and whatever was in the cylinder next to it. Depending on where the others cylinder is in one of the four cycles it could be drawing burning power stroke or exhaust gases which would add heat to that cylinder and possibly super heating the gasoline mixture to it's unstable level. The reverse cycle could occur when as the other cylinder went through it's 4 cycles.

Papermaker

[SteelGreyM]

Given the millions of cars that leak their r134a out (with no regulation or checks) and the wide availability of refrigerant available at parts stores for people to refill back into their leaky systems to, you guessed it, leak again, it stands to reason the r134a from this M3 will effectively make zero difference to the planet. No one really gives a f*** about the environment, if they did they we would all stop reproducing and live in mud huts lol. Carry on.
But it is true, you do not need to disconnect anything from the AC system, just swing it aside carefully like I did (didn't want to hurt the environment) and absolutely take the front end off since it is so easy to do.
Also, OP, where are you located?

I like to say I care about the environment but at the same time im catless so count me out of this conversation lol.

Im in Chicago

[Icecream]

I do not recommend doing this at all. Venting refrigerant to the atmosphere is incredibly harmful. R134a has a global warming potential of 1430, meaning that releasing one gram of R134a would have the same global warming effect as releasing 1,430 grams of carbon dioxide (wikipedia).

Also, he'll need to refill his AC system anyway, so why not get the correct tools and drain the system correctly instead of dumping everything into the atmosphere?

Given the millions of cars that leak their r134a out (with no regulation or checks) and the wide availability of refrigerant available at parts stores for people to refill back into their leaky systems to, you guessed it, leak again, it stands to reason the r134a from this M3 will effectively make zero difference to the planet. No one really gives a f*** about the environment, if they did they we would all stop reproducing and live in mud huts lol. Carry on.
But it is true, you do not need to disconnect anything from the AC system, just swing it aside carefully like I did (didn't want to hurt the environment) and absolutely take the front end off since it is so easy to do.
Also, OP, where are you located?