C20LET - Fried forged pistons nr. 2-3, 1-4 ok

[Pet]

Hi, my  engine started to smoke, compression test shows 10.1-8.5-9.0-9.7, then removed head and now is all clear. Pistons (forged Wiseco's) nr. 2 and 3 are completly melted. All injectors are tested and are ok, ran with wideband of curse, no lean runs... Is it only a spark problem ?? (too much advance, too much heat ) ???
  But why only cylinders 2-3 which are firing (spark) together ???

[z0tya]

What about spark plugs? Color?

[Pet]

Last couple of km was totaly black, because oil was leaking... anyway I have posted here a photo of my spark plugs in may...
http://195.159.109.134/vemsuk/forum/index.php/topic,850.0.html

[MWfire]

what primary trigger settings you have?
I found that 2.0 16v has two types of trigger wheel, 6deg difference between them.

[Pet]

Yes, I checked with the timing light, that 68deg is my trigger settings. Before I have set 74deg (so smallar advance) for a longer period ( A few runs were with 64deg.....
It's strange, the spark plugs are in good condition (imho), no heat marks etc. ......
I think my shi.y spark map is the key for this 700Euro unsucessful story :/
Pls does anybody have the original stock C20LET spark map, or some proven one for this engine ? I can pay something for this, still better than another 700E for new Wiseco's....

[max]

Have you tuned your ignition map on rolls or road w/detcans?

[z0tya]

We run about 13 deg at 210 kpa with Yb cosworths, (cr about 8.5:1). But I am interested in too oem spark map...
Another tip - I don't know which was your max pressure - but put the max kPa bin much bigger, because Ecu can run out from the bin and interpolate bad.

[z0tya]

Another question what about on the 55-140 kPa / 700-1200rpm area? Why is this ?

[Pet]

No, I was preparing to go for dyno tuning in a few days.... The engine, until now, wasn't under heavy load for a long time (only a few,5- 6,1/4m sprints).
Hmm, my max boost was sometimes higher then 220kPa, maximum was 230-235kPa, but as I have said, only for a few seconds on the highway on VI gear.

Have you tuned your ignition map on rolls or road w/detcans?

[Pet]

Another question what about on the 55-140 kPa / 700-1200rpm area? Why is this ?

I took some ign map for C20LET from another Vems user (from user pages) ........cause didn't have any another starting point to tune ign map...

[max]

As much as I understand, I think thats why this has happend. Next time you MUST tune your cars ignition and only then drive with boost. Detonation will destroy your engine quickly. You should be lucky that only two pistions are dead.

[Pet]

Yea, but why only pistons 2-3 ??  1-4 are hitted to, but absolutely not so much like 2-3.

[max]

Dunno, maybe pros have answer to this.

I've heard that if intake mainfold is wrong made, it can have uneven flows to each cylinder so its leaner/richer mixture to some cylinders. Theoretically it can start to det.

[gunni]

As just stated you probably have unbalanced air flow to your cylinders.

this causes varying mixture between them and some can be to lean, that also does look like a little to advance

What is the compression ratio of this engine?

Those black dots on the ceramic on the spark plug is a sign of detonation.

[Pet]

Hmmm, don't think, cause I am using a stock C20LET manifold from factory...