but where has the missing piece gone?
other observations.... indications are that there was also a lubrication issue on one of the cams. Timing chain streached. Haven't got the pistons out yet but will keep you informed.

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did you have any valves bent ? I have the same damage to the piston .The part that broke off could have been sucked out of the exhaust valve and into the muffler

 

haven't had the valves out, but they look to be seated properly and no sign of impact damage. You are probabley right though because the rings are intact so bits must have gone "up" rather than "down" l have three pistons with pieces missing, is that a record?

 

What type of FI do you have?

 

How much oil where you losing weekly? Can you tell us if any of your piston rings are damaged when you are done?

 

uk...give us some background on what happened here? I am lost? What type of F.I? What kind of failure...other mods??

And what missing pieces are you refering to in the pic?

 

Another detonation victim....you can tell by the ring land area being broken at the point FARTHEST from the exhaust valve.

You guys need to figure out what the HELL is going on with these motors.

Sorry to hear this, but hopefully it gives you motivation to build her stronger and lower the compression a bit.

 

Couldn't agree more IceY2k1Max. I'm very sorry to hear about your car UK350GT and I hope things can work out for you. I was about to go FI but will delay that until I have enough $$ for the motor build up as well. I will have to look at my APS kit in the box for a while.

 

That's spot on and most likely too much boost presure for the fuel octane............my best guess.

You guys really need to get a handle on setting up the boost pressue curve and ignition timing for a give level of octane fuel.

You guys really need to get the ignition timing map well sorted to avoid a repeat of this unfortunate experience.

Hope all goes well with the engine repair...............maybe time to go for some lower comp pistons if you have to do an engine rebuild anyway.


Peter

APS

 

The car has done 12k miles the last 6k miles with a ATI procharger (7lb pulley). The car has always used oil from new, but it was getting worse and when number 2 plug oiled up I assumed there was a problem with the piston rings in that cylinder. A compression test showed 160psi in that cylinder all the other read around 180psi. I changed the plugs at this time to HKS/Denzo, heatrating 9. Ran the car for 500 miles (out of necessity) untill a plug gave out again, this time No6. The porcalain insulation had dissapeared! Off came the head and there you have it. Pistons 3 4 5 have the same damage.

There were NO, I repeat NO, audible signs of detination. Three different people on different occations checked for it. I hit the rev limiter once in all that time, and what really disturbs me is that right up to the end the car was a flyer.

Now the embarissing part. I'm making this post in the hope that it helps the community in some way, I do not need to be ridiculed for my ignorance in FI science or for putting my faith in a kit manufacturers "know how" But the car was running on standard timing and the piggyback FMU that came with the ATI kit. I didn't Know about the timing issues untill joining here a month or so ago, would you believe I'm wating for a J&S at the moment.
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That makes me feel better (still sorry for your loss though). I thought that after you said ATI with 7 psi, I could have been in trouble.

I have the 9 psi pulley however I have the TS ECU flash for FI custom tuned to my car. I also have the AAM spec fuel solution (larger injectors, rails, return system, Walbro fuel pump) and my A/F at WOT is spot on 11.5 across the board.

You may want to consider this if you plan on going FI again.

 

my AF at WOT was 11.5 on the three occasions I had it checked.
I assume the damage evolved. I think the likely cause is fuel grade. In the UK 97 octane is the best you can get. Japan use 101 I believe. Timing becomes crutial.

I'm not scare mongering but there where no audible signs of detination and performce was not degenerative. I even ran a hose and cup (home mad stethascope) under the hood so I could listen to the engine underload whilst I sat in the car. so be aware

 

Oh dear...now I see the damage.

 

You really need to have the engine thoroughly dyno tuned to suit the local fuel octane...................otherwise you will run into the same detonation related damage again.

I have a friend in the UK (an usssie) who is a GUN tuner and could help you no end to get the engine tuned safely and performing really well.

Pm me if you like and I will give you the information.

Peter

APS

 

Why does detonation destroy the ring land area "at the point FARTHEST from the exhaust valve"? Also I seem to recall reading somewhere that oil in combustion chamber will effective reduce the fuel octane. Is this true?