[Kiki_95]

Hi all
the engine does not turn round but really very very slight ! thinking it was an injector .. I reversed after coil, spark plug. eventually take the compression and surprise from 1 to 5 12bar and 13bar and cylinder 6 .... 6bar ..
I exit the engine I control the cylinder head everything is perfect so I after removing the pistons 6 and surprise

[DreadFox]

Ewww....details on engine modifications, tune and when this happened?

[Kiki_95]

Originally Posted by DreadFox

Ewww....details on engine modifications, tune and when this happened?

Turbo Hybrid 24psi peak finish 20psi
98 and E85 (40%)
with METH

last result on dyno 547cv 545lbft

[Spxxx]

More details please, oh no.... this was on a 1M, sorry sir.

What kind of tune, timing, vanos changes, AFR?

[Whosdady]

Originally Posted by Spxxx

More details please, oh no.... this was on a 1M, sorry sir.

What kind of tune, timing, vanos changes, AFR?

+1

[doc 335]

Looks like detonation on cylinder 6
Could've been a lean condition on that cylinder

[Kiki_95]

log is attached

[Steve @ BMS/Fuel-It!]

Timing on 4 and 6 is non-existent and 5 is very poor.

Meth wasn't enabled via JB4, were you running a stand alone system?

Fueling looks normal. Bank 2 trims isn't being monitored but AFR's were stable on both banks and targeting about 12.8:1 up top.

Sorry to hear of the luck...forged pistons for the rebuild?

[Optigrab]

how many miles on the engine?

[jk135i]

I wonder if thats what happened to my engine, I have no compression in cylinder 5 but the only code I get is cylinder 5 misfire and a running diagnostic shows cylinder 5 running incredibly rich.

[boost junkie]

Originally Posted by jk135i

I wonder if thats what happened to my engine, I have no compression in cylinder 5 but the only code I get is cylinder 5 misfire and a running diagnostic shows cylinder 5 running incredibly rich.

Most likely.

[DreadFox]

Originally Posted by Kiki_95

Turbo Hybrid 24psi peak finish 20psi
98 and E85 (40%)
with METH

last result on dyno 547cv 545lbft

Oh well, you were probably at the limits of factory pistons with numbers like that anyway. Good luck on the new build. I hope those scores in the cylinder wall aren't too deep that they won't clean up without going to oversized pistons.

[DreadFox]

Originally Posted by Steve @ BMS/Fuel-It!

Timing on 4 and 6 is non-existent and 5 is very poor.

Meth wasn't enabled via JB4, were you running a stand alone system?

Fueling looks normal. Bank 2 trims isn't being monitored but AFR's were stable on both banks and targeting about 12.8:1 up top.

Sorry to hear of the luck...forged pistons for the rebuild?

I haven't pushed the N54 anywhere near as hard as you guys, and this is my first experience with direct injection. With that said, the AFR to me, is way on the lean side for basically pump fuel and 1.5 atm but I'm used to tuning on 2 valve conventional head pushrod engines with port injection or carburetors. I know with direct injection you can get away with AFRs that you can't in conventional engine design. I am used to seeing 11.5-12:1 AFR on straight unleaded, and 12.0-12.5:1 on C or Q16. And any ethanol blending would warrant richening the mixture.

I've always considered 11.5-12:1 on pump to be the safest ratio even though 12-12.5:1 does make more power. The reason being is that the added fuel has a cooling effect on combustion and gives you a bit more cushion when running pump fuel. Never actually measured it or tested but lots of people I know go by that rule and so I adopted it. What's the safe AFR target for the N54 above 20psi on pump fuel, whether E85 mix or straight unleaded? Running an E85/pump mix, I would want my AFR well into the 11.0-11.5:1 range, would this tuning window carry over to a max effort N54 engine?

I haven't looked at the logs, but if the meth didn't come on and the mixture went on the lean side then that would definitely eat up a factory piston. Broken second ring land, scoring/scuffing on the piston skirt, and salt and pepper spattering along the o.d. of the piston crown says detonation to me which would be caused by that lean condition.

[bk335xi]

"You're lucky that 100 shot of NOS didn't blow the welds on the intake manifold."

"Now me and the mad scientist gotta rip apart the block and replace the piston rings you fried."

I kid, I kid. Sorry OP.

[Spxxx]

That's about right, most are running a tad leaner on e85 mixes due to fueling limitations. My rule of thumb is 12.5 on E50 and potentially 12.6 on higher blends. With pump, definitely nowhere above 12:1 because you need more head room without the Octane - hell I see decent timing corrections even on the stock tuning.

[DreadFox]

Originally Posted by Spxxx

That's about right, most are running a tad leaner on e85 mixes due to fueling limitations. My rule of thumb is 12.5 on E50 and potentially 12.6 on higher blends. With pump, definitely nowhere above 12:1 because you need more head room without the Octane - hell I see decent timing corrections even on the stock tuning.

So leaning out the mixture with E85 mixes is to compensate for fuel delivery capacity limitations while still increasing peak power? Stoich richens as alcohol content goes up so I've always richened up the mixture as well while adding timing to make use of the higher octane content. For sure you make more power on the leaner side but you risk parts breakage as well because your safe window is reduced. I'm not criticizing, just asking questions because like I said, I'm still adjusting to this direct injected fancy stuff. I just wonder if OP had run a richer AFR then maybe the engine would still be living, and how many more engines will suffer a similar fate.

Leaning out the AFR for power has always been one of those things you have to be super careful with because the engine will literally eat itself up while making max power. You can bump up the timing until it stops making more power and after that point power usually drops with more timing and you don't usually hurt anything. Adding boost kinda does the same thing with more risk to popping a head gasket but your hard parts usually will stay together. Do you read the spark plugs when creeping up on the peak tune?

OP, how did your spark plugs look in this cylinder compared to the others? And have you pulled any of the other pistons?

[Terry @ BMS]

Looks like a detonation issue to me too. Seen a lot of blown pistons with non-integrated meth kits lately. Motors must be getting old.

If you're going to use meth integrate it and run map 3 so you at least have some basic safety in place. It doesn't guarantee the motor won't blow at high power levels but it's going to dramatically reduce those risks.

[Jewber]

I would think if using meth the engine stops having the fuel cooling advantage of a DI engine and is more like a normal engine so people running meth should run richer fuel ratios.

[Kiki_95]

the engine 43mkm I remove other pistons good look around there are no cracks all I presents a piston on a base in good condition low engine STOCK

[bmw135pls]

What gear were you in and were you wide open when it failed? Auto or manual trans? Just asking for my own knowledge.

[harrychiu012]

You can see it in the log, he was on 4th gear running map 6l. it's interesting how cyclinder 4 and 6 were nonexistent and toward the end, there's some data captured on cyclinder 5.

[Kiki_95]

Originally Posted by harrychiu012

You can see it in the log, he was on 4th gear running map 6l. it's interesting how cyclinder 4 and 6 were nonexistent and toward the end, there's some data captured on cyclinder 5.

yes MANUAL

[Optigrab]

Originally Posted by Terry @ BMS

Looks like a detonation issue to me too. Seen a lot of blown pistons with non-integrated meth kits lately. Motors must be getting old.

If you're going to use meth integrate it and run map 3 so you at least have some basic safety in place. It doesn't guarantee the motor won't blow at high power levels but it's going to dramatically reduce those risks.

Would the knock sensors pick up on that and cut timing?

[v8bait]

I always try to advise people to only use meth as a track type tool to control iat, or as a supplement to hit rational afr with e85 (like 12.2 in gas afr instead of 12.6), not as an octane supplement to 91 octane. Sure it will clean timing up at any level, but I've always kinda disagreed at running race gas boost/timing levels on pump+meth. Out of everybody I've helped though only about 1/4 of people share this viewpoint.

More faster pl0x.

[bmw135pls]

Originally Posted by v8bait

I always try to advise people to only use meth as a track type tool to control iat, or as a supplement to hit rational afr with e85 (like 12.2 in gas afr instead of 12.6), not as an octane supplement to 91 octane. Sure it will clean timing up at any level, but I've always kinda disagreed at running race gas boost/timing levels on pump+meth. Out of everybody I've helped though only about 1/4 of people share this viewpoint.

More faster pl0x.

Interesting. So would you still advise to not run meth in a daily driver if you were using about a 95-96oct E30 blend, or are you specifically talking about people who run insufficient octane paired with meth?