This is what happened?



No signs of knock. Bearings are good. 1.3 bar charging with GT28 turbo.

 

Ouch! Not sure exactly what went wrong, but there had to be a little bit of detonation or just a really bad piston from the manufacturer.

 

I am going to say it's a cast vitara piston, judging by the dish and the rods that lack ARP bolts.

Fuel cut combined with full-throttle shift can lean it out for a split second with boost, enough to hose a piston. Actually it only takes ONE problem lasting .001 seconds to crack a ringland. Another thing that can cause that it excessive ring clearance - the ring groove being much bigger than the ring thickness.

 

Care to give some more details about the engine ? A ring landing has let go. It could be det related...

 

The ring grove is good.

 

glad thats cleared up

any more info?

 

What do you want to know? What to see what the data say.

 

details on the engine..?

When did it let go? How did you come about this problem?

WOT AFR's and boost ign.. information needed to properly diag this problem.


from just the pic, some knock you couldn't hear happened.

 

^^^ Exactly... we're not all mind readers OP. If you want help your going to have to at least make some effort.

 

D15B7 engine, with stock header.
YCP pistons
H connecting rods
GT28xx turbo (Now I do not know what type, but not too interesting)

Here is the engine ignition table, and latest log:

Blue:boost
Green: injector duty cycle
Black: rpm
Purple: AFR

 

seems you were having some low rpm / high load knock.

from your datalog graph... seems if you mashed it at like 2k, it would knock until around 4500rpms or so..you were also running pretty lean.

whats the plugs look like?? need AFR that graph is all chopped up.. If you are going to use crome, make sure you are using it with the demon..

 

I speak very bad English. Do not fully understand.
So think the problem is between 2000-4500? There are many pre-ignition? Or where the AFR is too poor?
I'm looking at knock sensor. Not indicated.

 

Its fine, i'll do my best to explain and understand you.


What is your Air to fuel ratio @ 2k-4500rpms. Its possible there is some pre-ignition.. you need to be using CromePro's logger via the demon board, if you are using a 2nd hand logger you wont pick up some knock.

Using crome isn't bad but i'd suggest looking at better software. eCtune or neptune would be my first choices.

 

looks like lean spikes at 2200-2300rpms and from 3200-4300rpms. I'd take a look at the fuel and timing at those rpm. What type of gas are you using and what's the octane rating?. It's detonation related and the spike at 3400rpms is what could of broke the ring lands.

 

 

AFR:
2500 about 12.5 and about 900-1000mbar
3000 about 12.0 and about 1200-1250mbar
3500 about 11.8 and about 1400-1450mbar
4000 about ...here is the spike.... 1700-1800mbar.
4500 about 11.8 and about 2000 mbar... (this is poor??)

If I use the cromePro, is that good?

 

They give him more fuel?
Or reduce the pre-ignition?

 

your on crome now.. you need to unlock pro to use the datalog version, it'll make tuning much easier.

2ndly, i'd add more fuel where the spike is..

 

Using crome free/pro you have too much ignition when high boost. I have logged with pro that ign map says 10, 8, 6 degrees and datalog still shows like 16. It doesnt pull timing enough. Somewhere fix for it but with crome gold it pulls enough timing. Maybe get ectune for better EMS. Im using ectune for my car and crome gold for other cars tuning.

 

I looked at the graph again i would definitely check the charging system also and the fuel pump. If the charging system isn't operating properly you would see a drop in your fuel pump performance and also a lean condition at higher rpms which will also cause detonation. Insufficient voltage kills fuel pumps and engines.

 

Lean spikes? Where?

2200-2300 spikes from ~13.5 to ~14.5 with a low TPS%. His timing in that range is really low too. He could be 15+ afr with that and the car won't suffer.

3200-4300 doesn't really spike, it jumps from 11.5 to 12.0 real quick. Under full boost at high TPS the fuel is well under 12, closer to 11.

Lastly Volts are not on that display. I know it says 2.9 or something on the legend, but it's not on the graph (which is probably why it is saying that).

Also, his timing is RIDICULOUSLY low for 1.3bar (19psi). -1.5 degrees?! That ignition cylinder is probably hot as hell. That being said, this is Crome we're talking about. But with those settings there is no way in hell he was detonating (if Crome is not doing it's good ole' switcheroo and just running whatever timing it feels like).

I'm not sure if I agree with the "it was det" opinion either. From what I'm seeing in the datalogs and the timing he shouldn't be detonating at all, or even be close to it. Only way is to run 87 octane... so I'm kinda leaning towards piston defect.

 

How about if he got the exhaust valves so hot from having the timing so retarded it caused the mixture to pre ignite. It can happen....

 

I agree. I can't really see any damage from detonation on the piston tops, and I really doubt detonation would take out the second ringland without taking out the top. If I had to make an educated guess, I'd say the ring gap may have been too tight. If it got too hot in that cylinder, the ring ends butt, push out on the piston, and POP!

 

PS, cool setup. forged rods in a D15. dont see that often!

cracked ring lands are almost always from detonation

 

have a nice day