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  #1381  
Old 08-12-2014, 10:07 PM
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Quote:
Originally Posted by Rossco View Post

That motor was pinged, boost spiked to 29psi, belted on skid pans, flogged at Collie & taken to 8500rpm regularly.......Not a single piston 'fatigue' failure.... In fact it would not die!

These motors actually had real forged pistons.

If any model is going to suffer metal fatigue in it's pistons it will be the EJ255/Ej257 hyper crap chocolate pistons......

EJ207's just love 12.4:1 Afr's on boost haha!
i must be real unlucky then
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  #1382  
Old 08-12-2014, 10:26 PM
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AEM wideband, bosch sensor, placed after turbo, before cat.

So it is knocking killed the engine, right?
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Last edited by s20525xxx; 08-12-2014 at 10:34 PM.
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  #1383  
Old 09-12-2014, 12:15 AM
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Quote:
Originally Posted by dnbosiris View Post
i must be real unlucky then
Or VERY VERY lean

What were the AFR's like before it popped?
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  #1384  
Old 09-12-2014, 12:59 AM
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Quote:
Originally Posted by s20525xxx View Post
AEM wideband, bosch sensor, placed after turbo, before cat.

So it is knocking killed the engine, right?
Catastrophic detonation is not related to fatigue.....You said "I think fatigue is the reason why most old sti has piston failure" - You are not correct in your assumption......Most of them Die from big end bearing failures.

The STI Bug in question failed due to a leap in Volumetric efficiency that the ECU was never designed to compensate for, which probably lead to severe DET.

Detonation is a pressure spike with enough energy to crack cylinder bores, bend conrods & shatter pistons.

Engine Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration.

The sharp spike in pressure creates a massive force in the combustion chamber. It causes the structure of the engine to ring, or resonate, much as if it were hit by a hammer. Resonance, which is characteristic of combustion detonation, occurs at about 6400 Hertz. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes.

The high impact nature of the spike can cause a clean fracture of the ring land, bend conrods and fractured valves-intake or exhaust.
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  #1385  
Old 09-12-2014, 05:59 AM
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Quote:
Originally Posted by dnbosiris View Post
i must be real unlucky then

Show then the log simon?
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  #1386  
Old 09-12-2014, 07:15 AM
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ok here is the torque log. this is the section in which i believe detonation occurred
outside temp was about 34c. intercooler spray was being used. this is after about 1hr of driving with no issues whatsoever


note: in terms of the AFR's, since they are readings from factory o2 sensors and not wideband, how accurate are they?

loggy log

Last edited by dnbosiris; 09-12-2014 at 07:34 AM.
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  #1387  
Old 09-12-2014, 07:23 AM
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Lol, closed road.
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  #1388  
Old 09-12-2014, 07:39 AM
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Look at tve lines around 12:46:21. Thats pretty lean for full boost.
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  #1389  
Old 09-12-2014, 07:46 AM
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I'm sure it had speed when I looked at it 15 minutes ago..? Wise move.
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  #1390  
Old 09-12-2014, 07:46 AM
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Quote:
Originally Posted by Rslib72 View Post
If you had a set of forged Pistons in would this still have happened or would it just move on the next weakest link in the chain. Bummer about your engine mate hope it works out not to bad..

Mark
207 has forged pistons...
Rossco and Tweak.it.up like this.
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