Cracked piston, possible build in progress. Need some advice
idk it was just an idea lol / saying things lol
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Joined: 07-25-08
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From: Florida
he is in the other thread spouting about his af ratios.
he says 12.7 to 12.8 is the ratio to go with for power, yet ssturbd08 was tuned to that exact af ratio and blew his motor.
I do not disagree with leaning out a motor for more power, but at such high boost levels that are being run, it may not be such a safe idea, especially with a ton of timing.
he says 12.7 to 12.8 is the ratio to go with for power, yet ssturbd08 was tuned to that exact af ratio and blew his motor.
I do not disagree with leaning out a motor for more power, but at such high boost levels that are being run, it may not be such a safe idea, especially with a ton of timing.
Last edited by Terminator2; Jan 2, 2010 at 08:33 PM. Reason: Automerged Doublepost
Sea level maybe? High humidity 90% of the time?
There was a whole report about some stations in the houston area putting 87 in 93 tanks, but my thinking is the car would bias toward the low octane tables at that point.
I feel I might be grasping at straws with that one though.
There was a whole report about some stations in the houston area putting 87 in 93 tanks, but my thinking is the car would bias toward the low octane tables at that point.
I feel I might be grasping at straws with that one though.
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From: Florida
Sea level maybe? High humidity 90% of the time?
There was a whole report about some stations in the houston area putting 87 in 93 tanks, but my thinking is the car would bias toward the low octane tables at that point.
I feel I might be grasping at straws with that one though.
There was a whole report about some stations in the houston area putting 87 in 93 tanks, but my thinking is the car would bias toward the low octane tables at that point.
I feel I might be grasping at straws with that one though.
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From: Texas
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From: Waltham MA
GMS1
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From: Texas
"W" brand J&E, CP
J&E is very high end quality piston company like brand "W"
CP is another fine option.
Last edited by wiseguy; Jan 3, 2010 at 12:36 PM.
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From: San Clemente, Ca
Ok u know mote than me I just like je they haven't gone wrong for me yet but then again I haven't used any others
Option is also pankle they are expensive but very nice we run them in cup cars
Option is also pankle they are expensive but very nice we run them in cup cars
Last edited by cobaltssoverbooster; Jan 3, 2010 at 04:44 PM. Reason: Automerged Doublepost
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From: Texas
Brand "W" Correction
Pankle is CP when J&E was purshased they took 34 of the top J&E guys and started there own company. Also very high end quality.
Another very high end player in Cup is Mahle, They bought Clevite and are back dooring there decals on cup cars that way.
As usuall the US mfgs were slepping at the gate and let this happen.
It cost's $350,000 just to be part of the Cup contongency program the last I checked.
Any way Mahle a very formatable oppenent in the piston biz.
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From: Texas
Here's an interesting post I found:
"The LNF piston castings are made from a hypereutectic alloy. (high silicon content)
As such they have good strength, and low wear with a favorable thermal expansion characteristic.
Hypereutectic alloy pistons can be fitted to close tolerances since their thermal expansion at operating temperature is minimal compared to a forged piston.
The good cold fitment aids in the NVH department as well as the emissions department.
Now the trade-off: (there's always a compromise)
Hypereutectic alloy pistons tend to be more brittle and lack somewhat in high temperature strength compared to a forging.
What will kill a cast hyperutectic piston quickly is detonation.
The alloy being brittle simply will not withstand continuous hard detonation.
A forging is more forgiving in this respect in exchange for the requirement of looser tolerances and higher cost.
A lot of "horsepressure" can be made with cast pistons so long as detonation is avoided. That is where the knock sensing portion of the engine control circuitry comes in to play.
And don't forget those oil squirters in the LNF that direct cooling jets of oil to the undersides of the pistons, this helps as well.
Bottom line:
Uncontrolled detonation will kill a cast piston in short order.
This usually takes the form of broken (fractured) ring lands and/or skirts.
I speak from experience here. SBC days.
Uncontrolled detonation on a forged piston will beat the heck out of the bearings, crank, wristpins, rods, and will eventually melt pistons and valves.
I know about this too.$$$
Loud exhausts can mask the sounds of detonation.
This in conjunction with some mistuning and you have a perfect recipe for broken parts on any engine.
I speculate that as long as detonation is avoided 400 HP (crank) or more is doable without catastrophic damage to either cast or forged pistons.
And doing this will obviously wear everything in the drivetrain at an accelerated rate.
Cast is generally best for high performance street.
Forged generally best for racing as in long term WOT.
Rickey."
This is a link to that thread: http://www.solsticeforum.com/forum/f...sepower-60783/
Just thought it might help and give even more points of view
Sounds like the causes could be many things - including poor quality fuel for that kind of boost.
"The LNF piston castings are made from a hypereutectic alloy. (high silicon content)
As such they have good strength, and low wear with a favorable thermal expansion characteristic.
Hypereutectic alloy pistons can be fitted to close tolerances since their thermal expansion at operating temperature is minimal compared to a forged piston.
The good cold fitment aids in the NVH department as well as the emissions department.
Now the trade-off: (there's always a compromise)
Hypereutectic alloy pistons tend to be more brittle and lack somewhat in high temperature strength compared to a forging.
What will kill a cast hyperutectic piston quickly is detonation.
The alloy being brittle simply will not withstand continuous hard detonation.
A forging is more forgiving in this respect in exchange for the requirement of looser tolerances and higher cost.
A lot of "horsepressure" can be made with cast pistons so long as detonation is avoided. That is where the knock sensing portion of the engine control circuitry comes in to play.
And don't forget those oil squirters in the LNF that direct cooling jets of oil to the undersides of the pistons, this helps as well.
Bottom line:
Uncontrolled detonation will kill a cast piston in short order.
This usually takes the form of broken (fractured) ring lands and/or skirts.
I speak from experience here. SBC days.
Uncontrolled detonation on a forged piston will beat the heck out of the bearings, crank, wristpins, rods, and will eventually melt pistons and valves.
I know about this too.$$$
Loud exhausts can mask the sounds of detonation.
This in conjunction with some mistuning and you have a perfect recipe for broken parts on any engine.
I speculate that as long as detonation is avoided 400 HP (crank) or more is doable without catastrophic damage to either cast or forged pistons.
And doing this will obviously wear everything in the drivetrain at an accelerated rate.
Cast is generally best for high performance street.
Forged generally best for racing as in long term WOT.
Rickey."
This is a link to that thread: http://www.solsticeforum.com/forum/f...sepower-60783/
Just thought it might help and give even more points of view
Sounds like the causes could be many things - including poor quality fuel for that kind of boost.
These cars seem to eat the front O2 sensor since it's in the turbo's exhaust housing. When that front O2 goes bad, the fuel trims go way out of wack and even my own car would have considerable KR thru light accel or WOT when it went bad. I didn't hear or feel it, but because I log the car constantly, I was able to see something was wrong. Then the idle went funky and that was the tell tale sign for the O2.
Im sure there are people out there now running on a bad O2 and don't even know it, especially those without a RPD to monitor KR on the fly.
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Joined: 07-25-08
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From: Florida
Its in the tune, as this writeup states well! High boost = high cyl pressure + heat, add some knock to the mix and watch the piston beat itself to death.
These cars seem to eat the front O2 sensor since it's in the turbo's exhaust housing. When that front O2 goes bad, the fuel trims go way out of wack and even my own car would have considerable KR thru light accel or WOT when it went bad. I didn't hear or feel it, but because I log the car constantly, I was able to see something was wrong. Then the idle went funky and that was the tell tale sign for the O2.
Im sure there are people out there now running on a bad O2 and don't even know it, especially those without a RPD to monitor KR on the fly.
These cars seem to eat the front O2 sensor since it's in the turbo's exhaust housing. When that front O2 goes bad, the fuel trims go way out of wack and even my own car would have considerable KR thru light accel or WOT when it went bad. I didn't hear or feel it, but because I log the car constantly, I was able to see something was wrong. Then the idle went funky and that was the tell tale sign for the O2.
Im sure there are people out there now running on a bad O2 and don't even know it, especially those without a RPD to monitor KR on the fly.
I looked over at the scanner and it was showing 5-6* of KR at at advance of 8-9*. 
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From: Tejas
Its in the tune, as this writeup states well! High boost = high cyl pressure + heat, add some knock to the mix and watch the piston beat itself to death.
These cars seem to eat the front O2 sensor since it's in the turbo's exhaust housing. When that front O2 goes bad, the fuel trims go way out of wack and even my own car would have considerable KR thru light accel or WOT when it went bad. I didn't hear or feel it, but because I log the car constantly, I was able to see something was wrong. Then the idle went funky and that was the tell tale sign for the O2.
Im sure there are people out there now running on a bad O2 and don't even know it, especially those without a RPD to monitor KR on the fly.
These cars seem to eat the front O2 sensor since it's in the turbo's exhaust housing. When that front O2 goes bad, the fuel trims go way out of wack and even my own car would have considerable KR thru light accel or WOT when it went bad. I didn't hear or feel it, but because I log the car constantly, I was able to see something was wrong. Then the idle went funky and that was the tell tale sign for the O2.
Im sure there are people out there now running on a bad O2 and don't even know it, especially those without a RPD to monitor KR on the fly.
I think others have reported this too.
I just got my car back from the dealer. I have an 09 TC that the #1 piston was cracked. I did have a Trifecta Infiniboost tune but I don't feel it was the cause of the problem. The dealership knew about other LNFs with #1 piston being cracked. How many, I am not sure of. Mine did not show up until I was showing off to my brother-in-law and took the car for a quick sprint from 70 to 120 in 5th gear and let off. I then noticed my engine light on and power reduced message. Other than that, the car drove fine and I would not have really noticed any problems. The reduce power message went away after a few seconds and the engine light turned off by the next day. While driving it normally the day after, I got the engine light again and day it would blink every now and then while idling. So I put the car back to stock and took it to the dealer. Currently stock right now while I re-break in the new piston and rings.
back on topic.
On the infiniboost too! So, usually 26-30 psi, then you do WOT in 5th which will be over 30psi and you held it WOT for a fair amount. Im sure it wasnt tuned for that, prolly had some Knock while making insane heat and cyl pressure. Not surprised the outcome was failure there.
I tried to tune my car to be able to WOT in 5th, I could only do short bursts before I saw the Cat Temp just sky rocket. I stopped doing that LOL...
I tried to tune my car to be able to WOT in 5th, I could only do short bursts before I saw the Cat Temp just sky rocket. I stopped doing that LOL...
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From: Florida
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Joined: 07-25-08
Posts: 12,450
Likes: 6
From: Florida
On the infiniboost too! So, usually 26-30 psi, then you do WOT in 5th which will be over 30psi and you held it WOT for a fair amount. Im sure it wasnt tuned for that, prolly had some Knock while making insane heat and cyl pressure. Not surprised the outcome was failure there.
I tried to tune my car to be able to WOT in 5th, I could only do short bursts before I saw the Cat Temp just sky rocket. I stopped doing that LOL...
I tried to tune my car to be able to WOT in 5th, I could only do short bursts before I saw the Cat Temp just sky rocket. I stopped doing that LOL...
ZOMG run for the hills!!!
A majority of this is driver and tuner error. Let's not scare the site like little children in a scary bedtime story.
A majority of this is driver and tuner error. Let's not scare the site like little children in a scary bedtime story.
Last edited by wantedSS/TC; Jan 25, 2010 at 11:42 AM. Reason: Automerged Doublepost