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PostPosted: Mon Apr 01, 2013 12:45 am 
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Joined: Wed Jul 13, 2005 12:06 am
Posts: 4743
Location: Perth, Western Australia
Car Model: ST205
Toyota Celica GT-Four ST205 UK Spec: 3" H&S Downpipe and front pipe, Blitz NUR Spec R 70mm centre and back system, Motec M4 Pro ECU, AIM Digital Display, Blitz air filter, ERL Aquamist Water Injection, output circa 330bhp @ 1.5bar.

The car had been used for track days since I bought it in 1997 so for it to last ten years in various states of tune wasn't too bad. The shell and transmission now have a second life in my track toy project which has been well documented in my Track Weapon build thread. The blown engine has been used for mock-up purposes during the build but now that this is virtually complete I finally got the opportunity to pull it apart and see what had failed during the track day.

The engine failure occured at the Bruntingthorpe Prolex Toyota Day in 2007. Water Injection airlocked and within half a lap the engine lost its edge and the car slowed. Came straight into the pits with the engine sounding like it was firing on three cylinders. Didn't seem too bad so drove out to the village for the flat bed to pick me up. Probably a bad move as most of the oil in the sump ended up being pumped into the turbo and intercooler.

Cylinders 1 and 4 display signs of foreign object damage to the piston crowns

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Cylinder 1

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Piston 1

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Cylinder 2

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Cylinder 4

Broken spark plug electrode and ceramic insulator visible. I suspect the ceramic has caused most of the damage


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Cylinder block No 1 bore appears to have aluminium smearing

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The crankshaft journals also show signs of scuffing but it should be salvageable. The shells on the No 1 big end are worn down to the backing plate.

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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PostPosted: Mon Apr 01, 2013 1:08 am 
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Joined: Tue May 01, 2007 9:21 pm
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Location: lancashire
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Thats a cracker don I never have cars mapped relying on the w/i purely because of this, usually just have this for hot day switch ons as a safeguard

Martin

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PostPosted: Mon Apr 01, 2013 1:21 am 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
Car Model: None
You did a proper job on that one, I have multiple tries with mine :lol:

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PostPosted: Mon Apr 01, 2013 1:24 am 
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Joined: Wed Jul 13, 2005 12:14 am
Posts: 3265
Location: Camberley, Surrey
Car Model: ST205
Any thoughts on the failure mode - clearly number 4 cylinder has a problem as the spark plug tip is missing but number 1 cylinder shows the massive damage to piston and bore.

I wonder if the two events were separate or related somehow.

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PostPosted: Mon Apr 01, 2013 9:58 am 
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Joined: Sun Oct 01, 2006 2:14 pm
Posts: 1098
Location: sunny sleaford- lincolnshire
Car Model: ST205
thats some pretty impressive damage going on there Don!


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PostPosted: Mon Apr 01, 2013 12:15 pm 
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Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
The damage looks as I expected, holed piston

I don't think the air locked wi caused it - I seem to recall a good few laps of Donington without wi without that result
However looking at the damage to other cylinders I also doubt my fuel pump issue guess too as that should wreck all the cylinders not one
I'll hazard a guess that it broke a ring land in #1 and black death did the rest


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PostPosted: Mon Apr 01, 2013 12:36 pm 
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Joined: Sat Sep 02, 2006 3:13 pm
Posts: 3679
Location: Bournemouth
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330 seems a low figure for 1.5 bar and decently mapped ECU by modern standards. Maybe our recent discussion on dyno accuracy is applicable ? or was it 330 at the wheels ?

I would suspect high internal temperatures and/or detonation. From the broken plug on one cylinder and melted piston on another, it's not just limited to one cylinder. From personal experience, once a ringland has gone pushing the engine hard results in melted piston as the increased blowby carries the heat down the side of the piston rather than leaving it above the much thicker, oil cooled, crown.

Did the car have any other symptoms in the run up to failure ? e.g. misfires, flat spots, etc.

My current theory on my own failures is that it was down to overheating igniter (dwell time too long) causing intermittant advanced ignition. The car used to get just the occasional misfire when pushed hard, and ringland failure always seemed to follow these occasions.

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