Post by jaberwaki on Sept 12, 2005 1:29:08 GMT -5
welp i finally had time this weekend to take apart my car to find out the source of the oil burning that started at the track on my last trip.
up until this time we believed it to be 1 of 2 things. either a valve stem seal going completely and allowing oil to seep from the rocker valley into the cylinder, or 2 a piston ring had given up the ghost...
well it turns out it was niether,
for reasons still not known i had a hole burned strait thru #7 piston.
and the peices that broke off and burned up had FUZED themself to the combustion chamber of the heads!!! :eek:
so making a long story short, I am done for the season while i save up for a new shortblock.
now enter the portion were this becomes a tech question thread...
the cause of this failure is not jumping right up and showing itself. infact it is really confusing...
heres what we DO know.
1. the damage is without a dought the result of detonation, the way it burned up it is something i have seen several times..
2. the motor was tuned to run FAT, because we did not have time for a solid dyno session, my tuner (chad) and i set the fuel to run alittle on the rich side.
3. the fact that we were running rich was evident in the other cylinders as NONE of them show any signs of running lean at all...
4. the hole is not in the center of the piston, it is on the outermost portion of it.
so now comes the problem. why??? why did this one cylinder detonate?
we have it down to 2 possable troubles...
1. injector failure, i am going to try to prove or disprove this ASAP. these are brand new racetronic disk style 42lbs injectors, there is no reaon it should have failed but it must be tested to know for sure.
2. some unseen trouble with the afr head caused a hot spot. basically some trouble in the cooling passages in the head like a blockage or even a bad cast causing the combustion chamber of #7 to develop a hotspot, once getting hot enough it would cause predetonation, also backed up by the fact that the metal off the piston fuzed itself to the head in the same spot it burned from.
these are the only 2 reasons i can think of... if you have any ideas i am totally open for them...
i will not place the blame on ANYONE or anypart until i know 100% what the cause is, the reeasons listed above of only theory until we have had chance to know for sure... once the trouble is found, if it turns out to be one of the 2 listed above, being that the parts were installed new only 1500 miles or so ago i will keep you informed as to how said vendor responds and/or makes right...
it really sucks , but i am not going to cry over spilled milk, next year i will be back with a new shortblock and faster then ever...
up until this time we believed it to be 1 of 2 things. either a valve stem seal going completely and allowing oil to seep from the rocker valley into the cylinder, or 2 a piston ring had given up the ghost...
well it turns out it was niether,
for reasons still not known i had a hole burned strait thru #7 piston.
and the peices that broke off and burned up had FUZED themself to the combustion chamber of the heads!!! :eek:
so making a long story short, I am done for the season while i save up for a new shortblock.
now enter the portion were this becomes a tech question thread...
the cause of this failure is not jumping right up and showing itself. infact it is really confusing...
heres what we DO know.
1. the damage is without a dought the result of detonation, the way it burned up it is something i have seen several times..
2. the motor was tuned to run FAT, because we did not have time for a solid dyno session, my tuner (chad) and i set the fuel to run alittle on the rich side.
3. the fact that we were running rich was evident in the other cylinders as NONE of them show any signs of running lean at all...
4. the hole is not in the center of the piston, it is on the outermost portion of it.
so now comes the problem. why??? why did this one cylinder detonate?
we have it down to 2 possable troubles...
1. injector failure, i am going to try to prove or disprove this ASAP. these are brand new racetronic disk style 42lbs injectors, there is no reaon it should have failed but it must be tested to know for sure.
2. some unseen trouble with the afr head caused a hot spot. basically some trouble in the cooling passages in the head like a blockage or even a bad cast causing the combustion chamber of #7 to develop a hotspot, once getting hot enough it would cause predetonation, also backed up by the fact that the metal off the piston fuzed itself to the head in the same spot it burned from.
these are the only 2 reasons i can think of... if you have any ideas i am totally open for them...
i will not place the blame on ANYONE or anypart until i know 100% what the cause is, the reeasons listed above of only theory until we have had chance to know for sure... once the trouble is found, if it turns out to be one of the 2 listed above, being that the parts were installed new only 1500 miles or so ago i will keep you informed as to how said vendor responds and/or makes right...
it really sucks , but i am not going to cry over spilled milk, next year i will be back with a new shortblock and faster then ever...
k. 
