Carnage - need input
08-13-2015, 09:10 AM
#1
Carnage - need input Wanted to get a little input on what may of happened to the poor LQ9. Was running apprx 16psi and she let go at about the 1000' mark. Data Logs show everything was dandy....good oil pressure, coolant temp, AFR, fuel pressure. Here's what interesting...for some reason battery voltage started dipping which means fuel pressure just started to dip slightly but AFR stayed where it needed to be. Other than that everything was normal.
This run was with 100/93 octane mix, 16psi in high gear, and 16*. On this run I turned the meth off
to see if the car would pick-up. Only thing that picked-up was pieces of engine everywhere lol!
IAT's were 130*, AFR 11.5, oil pressure arrx 70psi, Fuel pressure 52 psi (43 base).
Now, 7 and 8 decided they didn't want to be in the engine any longer. Those pistons are pounded into globs of alum...can't do any detective work there. The remains of the rods still spin just fine on the crank! All the other pistons look good except #4 which looks like debris caused it to break. The crank although banged-up looks good too.
Hard to tell afterwards, but what could of happened here? I think something was wrong with this engine b/c it really didnt go faster from 10psi to 16psi. Could excessive backpressure contribute (83/74 turbine)? Cant believe that the lack of water/meth at 16psi could of done this.
This run was with 100/93 octane mix, 16psi in high gear, and 16*. On this run I turned the meth off
to see if the car would pick-up. Only thing that picked-up was pieces of engine everywhere lol!IAT's were 130*, AFR 11.5, oil pressure arrx 70psi, Fuel pressure 52 psi (43 base).
Now, 7 and 8 decided they didn't want to be in the engine any longer. Those pistons are pounded into globs of alum...can't do any detective work there. The remains of the rods still spin just fine on the crank! All the other pistons look good except #4 which looks like debris caused it to break. The crank although banged-up looks good too.
Hard to tell afterwards, but what could of happened here? I think something was wrong with this engine b/c it really didnt go faster from 10psi to 16psi. Could excessive backpressure contribute (83/74 turbine)? Cant believe that the lack of water/meth at 16psi could of done this.
08-13-2015, 09:26 AM
#3
Fuel pressure not rising 1:1 is a problem. 9PSI rise for 16lbs of boost in fuel pressure is not ideal.
You tuned it for Meth but shut it off, did you make any adjustments at all to timing when you did that?
Were you logging knock at all?
What heat range spark plug were you using? Looks like you lit the mixture off too early - Rod didn't like it and hit the eject button.
You tuned it for Meth but shut it off, did you make any adjustments at all to timing when you did that?
Were you logging knock at all?
What heat range spark plug were you using? Looks like you lit the mixture off too early - Rod didn't like it and hit the eject button.
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08-13-2015, 11:34 AM
#9
Fuel pressure not rising 1:1 is a problem. 9PSI rise for 16lbs of boost in fuel pressure is not ideal.
You tuned it for Meth but shut it off, did you make any adjustments at all to timing when you did that?
Were you logging knock at all?
What heat range spark plug were you using? Looks like you lit the mixture off too early - Rod didn't like it and hit the eject button.
You tuned it for Meth but shut it off, did you make any adjustments at all to timing when you did that?
Were you logging knock at all?
What heat range spark plug were you using? Looks like you lit the mixture off too early - Rod didn't like it and hit the eject button.
No big deal, I'm not bummed and just glad I didn't lose control of the car at ~130 considering how much oil I let out!!! I have a 5.3 sitting in the garage right now getting ready to drop it in.
Heads are wasted especially on 7/8.
08-13-2015, 11:48 AM
#10
The meth injection is so little that it doesnt seem to make much difference either way. I did not back timing off b/c I had higher octane fuel in there. No knock detection hooked-up, but all the other pistons look real good. BR7 plugs.
Other pistons look great, and it had a 100 octane mix in there, doubt deto would of thrown rods out of the block???
Other pistons look great, and it had a 100 octane mix in there, doubt deto would of thrown rods out of the block???
08-13-2015, 12:02 PM
#11
Bad gas? I filled up with what I suspected was bad gas a few years ago and instantly broke five pistons. It was gas in a little hick town that also carries 86 octane, I suspected either they put the 86 octane in the 91 pump and/or there was water in the gas, leaning more towards water and trash in the gas. Since you still have your tank of gas is there an easy way to test for water/non gas I wonder?
I also got methanol from a racetrack out here last year and it was obviously trash as they were pumping it out, the guy acted like I was nuts for not wanting it, I thought what if I was running a methanol car on that, it probably would have taken a ****. Maybe the 100 you got was contaminated or had been sitting for a long time?
I also got methanol from a racetrack out here last year and it was obviously trash as they were pumping it out, the guy acted like I was nuts for not wanting it, I thought what if I was running a methanol car on that, it probably would have taken a ****. Maybe the 100 you got was contaminated or had been sitting for a long time?
08-13-2015, 01:27 PM
#12
Ouch... Does it look like that #3 butted the ring and lifted? Or just torched the piston downward? Detonation can defiantly caused that IMO.
Do you have any previous pics of the plugs pulled after a run? Were 7/8/3 lean cylinders? I'm sure if 7 failed it could have taken out 8 on the way or vise-versa.
I'd get the injs flowed as well. Sounds like the collective AFR may have been in check, but individual cyls were leaning out, drop in pressure is a dead give away. What fuel rail setup are you using? Dead head? What pump were you using?
Do you have any previous pics of the plugs pulled after a run? Were 7/8/3 lean cylinders? I'm sure if 7 failed it could have taken out 8 on the way or vise-versa.
I'd get the injs flowed as well. Sounds like the collective AFR may have been in check, but individual cyls were leaning out, drop in pressure is a dead give away. What fuel rail setup are you using? Dead head? What pump were you using?
08-13-2015, 04:49 PM
#13
Not sure, will have them looked at. Although, closed loop didn't seem to go nuts here trying to compensate for something.
I'm going to drain it and start over...who knows if there's an issue here. Although the other pistons looked good.
Looks like #3 broke from debris getting wedged under the piston and between the crank, snapping the piston off of the rod. Does Not appear butted, just busted up. No plug pics on hand. Pressure was starting to drop b/c voltage was dropping - that I don't know why was happening...have to get the alternator checked. Unless the engine was starting to tighten up and voltage dropped????
Using china rails, return system with a Holley pump/reg, -8 feed and -6 return.
Bad gas? I filled up with what I suspected was bad gas a few years ago and instantly broke five pistons. It was gas in a little hick town that also carries 86 octane, I suspected either they put the 86 octane in the 91 pump and/or there was water in the gas, leaning more towards water and trash in the gas. Since you still have your tank of gas is there an easy way to test for water/non gas I wonder?
I also got methanol from a racetrack out here last year and it was obviously trash as they were pumping it out, the guy acted like I was nuts for not wanting it, I thought what if I was running a methanol car on that, it probably would have taken a ****. Maybe the 100 you got was contaminated or had been sitting for a long time?
I also got methanol from a racetrack out here last year and it was obviously trash as they were pumping it out, the guy acted like I was nuts for not wanting it, I thought what if I was running a methanol car on that, it probably would have taken a ****. Maybe the 100 you got was contaminated or had been sitting for a long time?
Ouch... Does it look like that #3 butted the ring and lifted? Or just torched the piston downward? Detonation can defiantly caused that IMO.
Do you have any previous pics of the plugs pulled after a run? Were 7/8/3 lean cylinders? I'm sure if 7 failed it could have taken out 8 on the way or vise-versa.
I'd get the injs flowed as well. Sounds like the collective AFR may have been in check, but individual cyls were leaning out, drop in pressure is a dead give away. What fuel rail setup are you using? Dead head? What pump were you using?
Do you have any previous pics of the plugs pulled after a run? Were 7/8/3 lean cylinders? I'm sure if 7 failed it could have taken out 8 on the way or vise-versa.
I'd get the injs flowed as well. Sounds like the collective AFR may have been in check, but individual cyls were leaning out, drop in pressure is a dead give away. What fuel rail setup are you using? Dead head? What pump were you using?
Looks like #3 broke from debris getting wedged under the piston and between the crank, snapping the piston off of the rod. Does Not appear butted, just busted up. No plug pics on hand. Pressure was starting to drop b/c voltage was dropping - that I don't know why was happening...have to get the alternator checked. Unless the engine was starting to tighten up and voltage dropped????
Using china rails, return system with a Holley pump/reg, -8 feed and -6 return.
08-13-2015, 05:31 PM
#14
Just throwing this out there. Do you have a 4 port steam vent system on the heads or block offs in the rear? I am asking because I have heard this can cause the rear 2 cylinders to run hotter than the rest thus making them more prone to detonation in those cylinders. If the engine was on the edge for some reason that would explain why only the 2 rear cylinders were effected.
08-13-2015, 05:57 PM
#15
Just throwing this out there. Do you have a 4 port steam vent system on the heads or block offs in the rear? I am asking because I have heard this can cause the rear 2 cylinders to run hotter than the rest thus making them more prone to detonation in those cylinders. If the engine was on the edge for some reason that would explain why only the 2 rear cylinders were effected.
yes 4 corner cooling system in place. Doubt that would contribute to rods coming out of the block. Scuffed pistons - maybe.
08-13-2015, 07:27 PM
#19
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Guessing is never good, but even given for that, I've wondered if your setup is a bit down on power. Both KBracing and I both run that same turbo on our trucks. We've both run bottom 11s (his 11.0 to my 11.1), my raceweight is 5k and his 5400. I also know of a silverado ss that went 10.9@126 on a 472/83 t4. So your turbo should have enough to propel you to mid 9s.
Based on the findings and the fact you turned off meth, sounds like you detonated. I read a post years ago by TJ@BakerEng stating that good fuel was critical to keeping a JY motor alive, and I believe every bit of it. I know running E85 has saved my *** on several occasions.
Based on the findings and the fact you turned off meth, sounds like you detonated. I read a post years ago by TJ@BakerEng stating that good fuel was critical to keeping a JY motor alive, and I believe every bit of it. I know running E85 has saved my *** on several occasions.
