This is the melted piston (No. 4)




This is the valves oneither chamber 2 or 3



This is the valves on chamber 4 where piston melted


According to tuner:

A/F was between 11.1 to 11.5 at WOT
Intake Temp was about 46 degrees max
Ignition was about 10 at 4000 rpm (onset of boost) and slowly crept up to about 21 between 5500 to 7000 rpm


what i can confirm from my meters:

Compression ratio is 9.0
Boost: running at max 1.65 bar
Ambient outside temperature was abt 27 - 28 degrees (2 am in the morning)
Oil temp die not exceed 82 degrees (sensor at oil pan)
Exhaust Temp did not exceed 720 degrees (sensor at beginning of downpipe just after O2 housing)

My cams settings:

Jun 272 duration Lift 10.8 for both intake and exhaust

Intake 5 degress timing 110

Exhaust 0 degrees timing 115


Was alerted to trouble when car was at about 6500 rpm when the oil pressure alarm sounded

The melting occured on the intake side of the pistons.

any ideas what happened?

 

What about your fuel settings ??

 

Fuel settings?

i am using sard 700cc injectors, sard fuel regulator set at 3.0 bar (vacuum off)

The wide band lambda according to tuner was between 11.2 to 11.5 at WOT.

 

Wow.. take a look at your fuel injectors.. its possible the one on the cylinder that nuked wasn't flowing adequately or failed and went lean..

 

Sent the injectors for testing.

They are workin fine. so the prob does not lie with the injectors.

 

How about your fuel pump ??? + 1.65 kg is some pretty stout boost.

 

I'm stumped.. I suppose a momentary lean condition in one cylinder could cause failure like that.. But since you had the injectors tested and their alright.. maybe electrical? Possibly the injector harness?

I guess detonation is also a possibility, but I've never seen anything like that caused by detonation. Another possibility is oil starvation or coolant starvation.. but that likely would have caused more damage than just a isolated hot spot.

The location of the melt on the piston is what confuses me.. its like it was real lean on one side of the piston... I honestly haven't burned up enough parts to have seen anything quite like that.

 

Looks like repeated abuse to me. That looks like detonation, pre-igniton will melt pieces like that. No matter how "safe" the tune is, there is always a mechanical limit with repeated straining of a component. There is a limit to the stock components and that's a perfect example. For constant and repeated high boost operation Forged internals are the only way to go.

 

I am exploring the possibility of pre ignition as well but cant confirm.

these are forged and coated (thats why it is black) pistons

 

Power enterprise 255 L fuel pump

 

Holy moses, you melted a forged and coated piston at only 1.65 bar? Were you on 93 octane?

 

HI im sorry to see that first of all...
i can tell you from experience because i did that to one of my turbo civics a long time ago when i started tuning my own..the egt your were reading was a bit low because of the location of the probe--I would say that your failure was caused by repeated exposure to detonation at more than likely high rpm where its harder to feel and hear it..thats what broke the ring lands--coupled with high cylinder pressures and temps...the whole thing was induced by too much boost....if your peak boost was 1.65 bar, that is just a smiggin under 24 psi--23.93 to be almost exact. thats a crap load of boost by any standard. that looks almost exactly like the number four cylinder from my civic..
sorry too see that.
rick

 

Sheesh Pred, what happened and when did this happened??? Recently on the trip up north??? man... stroker kit next? man, hope the guys here can help...

 

Not enough octane for your boost.

What compression ratio pistons are they?

Also, it is possible that oil entered the combustion chamber BEFORE the damage occurred. Oil has a very low octane, so it is best to not burn it in the combustion chamber.

 

98 octane