1st pass with 5.3 = 2 broken, 1 torched piston ???
07-07-2012, 04:27 PM
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1st pass with 5.3 = 2 broken, 1 torched piston ??? Let me give a quick run down of the combination.
2003 5.3 longblock
98# injectors
oem truck intake,throttle body
twin GT35 turbos (Chinese Ebay)
MS3 cam 113 lsa
Lunati duel springs (.650)
LS2 chain
E85 Fuel, no methanol injection or inter-cooler
This is in a 67 Camaro tube chassis ex-racecar. (3024 lbs.)
I have beat on this engine for 4 years on the street with no major problems. It had developed a really audible cold knock about a year ago, that lasted about 30 seconds after cranking, beginning to think the broken pistons my have been that way for awhile.
I took it to the track last week for the first time
18 psi boost, 10.2 afr, on e85 (gas scale) 17 deg. timing
These are the results : Broken pistons #1,#5 torched #7
The first 2 pics. are #7 piston. The last one is of piston #5 (#1 looks identical, no need for a pic.)
The top ring lands on 5 and 1 looked great, which leads me to believe the rings may have butted together breaking the lower lands.
I have replacement pistons to go right back in, I will open the gaps .005 more and see if this works.
Also #8 piston top ring land is starting to flake away at the intake valve location, very little, but noticeable.
Could this be signs of detonation, heat, excess fueling?
I do not have a steam vent on the rear cylinders, only the front two, could this have caused a problem?
2003 5.3 longblock
98# injectors
oem truck intake,throttle body
twin GT35 turbos (Chinese Ebay)
MS3 cam 113 lsa
Lunati duel springs (.650)
LS2 chain
E85 Fuel, no methanol injection or inter-cooler
This is in a 67 Camaro tube chassis ex-racecar. (3024 lbs.)
I have beat on this engine for 4 years on the street with no major problems. It had developed a really audible cold knock about a year ago, that lasted about 30 seconds after cranking, beginning to think the broken pistons my have been that way for awhile.
I took it to the track last week for the first time
18 psi boost, 10.2 afr, on e85 (gas scale) 17 deg. timing
These are the results : Broken pistons #1,#5 torched #7
The first 2 pics. are #7 piston. The last one is of piston #5 (#1 looks identical, no need for a pic.)
The top ring lands on 5 and 1 looked great, which leads me to believe the rings may have butted together breaking the lower lands.
I have replacement pistons to go right back in, I will open the gaps .005 more and see if this works.
Also #8 piston top ring land is starting to flake away at the intake valve location, very little, but noticeable.
Could this be signs of detonation, heat, excess fueling?
I do not have a steam vent on the rear cylinders, only the front two, could this have caused a problem?
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07-07-2012, 06:16 PM
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You have almost the same motor setup that Im building except different cam, same turbos, injectors, fuel, ect, but I will have dual intercoolers. I was wondering if you put in ARP's head bolts/rod bolts and/or changed the headgaskets.
Do you have any idea what kinda power your were making??
Do you have any idea what kinda power your were making??
07-07-2012, 07:25 PM
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I thought target on gas scale for e85 was still 11.5-11.7 range? 10.2 is way rich.
Im thinking all of the above.
Could this be signs of detonation, heat, excess fueling?
07-07-2012, 07:27 PM
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First pass at 18lbs??? There's your problem...
Not trying to be a jerk, but unless you've got one hell of a tune 18lbs is not a starting point. Next engine, start at 7-8lbs and go from there.
Not trying to be a jerk, but unless you've got one hell of a tune 18lbs is not a starting point. Next engine, start at 7-8lbs and go from there.
07-07-2012, 07:36 PM
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The only time I haven't data logged happened to be this time.
The tune has been pretty good in the past.
I did however just fill up the tank on the way to the track, I will have to
check the fuel.
It ran 7.20 at 103, felt strong thru 1st gear, and understandably got weaker and weaker, then pow! LOL
Going with meth injection
07-07-2012, 07:39 PM
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I only thought it had a great tune.LOL
I am going with 7 psi next time.
I got Greedy and Stupid!
07-07-2012, 07:41 PM
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You have almost the same motor setup that Im building except different cam, same turbos, injectors, fuel, ect, but I will have dual intercoolers. I was wondering if you put in ARP's head bolts/rod bolts and/or changed the headgaskets.
Do you have any idea what kinda power your were making??
Do you have any idea what kinda power your were making??
07-07-2012, 07:43 PM
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07-07-2012, 07:46 PM
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07-07-2012, 08:39 PM
#18
WOW. You almost had liquid pistons.
I agree with everyone else in that the intake temps might have been the cause and that could have caused it rattle and then pop.
If I were you I would go over my fuel system before you get it back together. I wonder if a fuel pump or regulator went bad or had a problem because she did get pretty hot.
The alcohol will be a huge help also.
Good luck.
I agree with everyone else in that the intake temps might have been the cause and that could have caused it rattle and then pop.
If I were you I would go over my fuel system before you get it back together. I wonder if a fuel pump or regulator went bad or had a problem because she did get pretty hot.
The alcohol will be a huge help also.
Good luck.
07-08-2012, 10:07 AM
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Holley 12-1400 Dominator fuel pump (55 psi base), this was the first thing I checked after getting it home.
10AN feed, 6AN return
100 micron pre filter, 98 lb. injectors , oem rails.
I never had it dynoed, it ran really well for 4 years with hundreds of miles put on it.
I think I just got too greedy with boost, on an average tune, with no cooling of the intake charge.
