NefMoto

My friedn have disaster in his car, he try to make a V max, but at 200 kmh he blown engine
(https://i.postimg.cc/FzKpH6Df/IMG-20200103-WA0018.jpg) (https://postimg.cc/Vr3n7Ky1)
Piston on 4. Cilinder has melted
I am wondering how this happen?
Engine have about 320 000 km, it  is slighly tuned to about 175-180 hp, have LPG sistem
He buy car with full cloget catalyst, the engine didn't make more than 120 hp, he remowe cat and put a stage 1 map on it

Well i see those guard pins at the block so piston was melted at the exhaust side and thats typical result of critical EGTs

And what caused this? Lean AFR as usual so dig it

Sorry for not posting other pictures,
How lean AFR and how much EGT schould be to cause this on 1.8 T engine with 170 hp?  :o

If we take in consider that car is driven normal most of time. The remap si made a two months ago

I am really wondering beacuse I was driving my AEB( when I didn't know much about this things)  at really late ignition, lean AFR, much more boost and much much harder, and there was no sing of anything similar in engine

"The message body was left empty."

Looks like the ring butted up agenst its sepf and blew the ringlands off the piston First before

Post the file thats on the car that way we can tell your buddy the shitty tune did it or not

LPG system was the cause i guess , my friend had a similar failure - about 150 km on autobahn with speeds over 200 kmh and the piston on one cylinder melted - propably bad lpg injector

Only critical LPG system failure could do this IMHO
LPG or not, post 2001 1.8t goes in Close loop all the time so AFR is controlled by engine lambda to target mixture even on LPG ...

I said that it is possible so it could be the cause


Soul87 a little offtopic - a4klub.pl?

Yes and on gaseous LPG there is no cooling effect.

What does ME7 do when it thinks EGT is high? Add fuel. Do you know what happens on LPG when you add fuel?
EGT goes up. Max enrichment on LPG should be 0.9, and it should be hard limited in software when LPG is active. And timing should be tuned for the higher octane rating to keep EGT in check.

Don't agree,

I'm installing LPG to cars, few times I had a chance to tune the LPG on cars with EGT sensor.
On lambda 0.75 - 0.85 EGT was the same on LPG as PB ...

Guys the car is driven on open road most of time in higest gear at 70-90 kmh. My friend really doesen't drive fast. And when he try Vmax the engine was running on petrol.
Realy often he was on autoban, and that was all at low speeds at 120-130 kmh

I can't read or post his flash beacuse is comercial tune from company that is a really good, and they are in motosport for a years

And why yust one piston?

EGT is lower on LPG by default because it burns cooler and because it is possible to run more timing.
But if you actually look at EGT, then after 0.9 it starts to increase. It also destroys the valve seats because it's still burning on it's way out.

It's not a matter of agree or disagree, it's basic combustion theory. If you have a gaseous fuel, then going richer will increase EGT and slow combustion, because there is no evaporative cooling effect.

Here is a head picture, maybe it can get us closer to solution. It is obevius that 4. Chamber have differnet combustion from others
We will also inspect petrol injectors, maybe it get stuck or something

So BTS should be switched off and and Lamfa set to 0.9? I am running a 1.8T with LPG and a stage 1 tune. Car has now 400k on the gaug and i am driving it since 160k on LPG. So far luckely nothing burned and it sees quite often 200 kmh and more.

On a NA engine it should be just fine because it´s anyway never going richer right?

NA engine goes richer too. Yes on LPG (unless you run liquid injection), you should never enrich past 0.9.
Higher EGT.

Thanks prj! Is there a rough guidance how much the timing can be advanced? Or can this only be done properly on a dyno?

On low load areas only on dyno.
Depending on the boost you run it is possible that on higher load also you will not have any knock limit and finding the correct timing will only be possible on the dyno.

I recall having to add a lot at low RPM and not having to add almost anything at high RPM, but this doesn't really help much - need to cell-by-cell dyno tune it.

Thanks again!