4B11 engine failure documentation thread
1.) 17000 miles @ failure
2.) Hole through side of block, at least 1 broken rod. Led to an oil fire which destroyed 1/3 of my engine bay. No symptoms up until catastrophic failure.
3.) Stock rod was either defective or they simply cannot handle 32+ psi on a CBRD BB-X turbo. From what I can see currently, the rod split clean in half and the big end is still in tact.
Moral of the story, the stock rods are weak as hell. I honestly spiked to about 36-38 psi 3 times on 3 partial pulls when I had some mapping issues with EcuFlash. That probably produced a torque spike of ~500 lb-ft which weakened one of the rods.
Oddly, the failure happened in 5th gear under 1/2 throttle while passing somebody going under the speed limit on I-29. I would convert back to stock and make the dealer fix it, but I honestly don't want another stock block that is incapable of handling a decent 450-500 WHP.
No tuning issues. 2-3 counts of knock max. 11.6 AFR with a large shot of methanol/water. Very conservative timing. 30-32 psi straight across from 3500 to 7500 rpm.
Must have just been too much for the stock bottom end to handle. *shrugs*
I'll find out soon if it was rod bolt failure, but it honestly doesn't look like that is the case. Nor should it have been because I neither make much torque nor rev past 7600 rpm.
edit: There are my modifications:
CBRD BB-X turbo, ported exhaust manifold & turbine housing, Invidia DP/TP/N1 catback, Cobb Intake + Inlet hose
Custom UICP, Snow Performance CH3OH/H2O injection, AMS inline fuel pump, 1000 cc/min DW injectors, Cossy fuel rail (doesn't matter, but just illustrating the adequacy of my fuel system), replaced OEM fuel relay w/ green one
2.) Hole through side of block, at least 1 broken rod. Led to an oil fire which destroyed 1/3 of my engine bay. No symptoms up until catastrophic failure.
3.) Stock rod was either defective or they simply cannot handle 32+ psi on a CBRD BB-X turbo. From what I can see currently, the rod split clean in half and the big end is still in tact.
Moral of the story, the stock rods are weak as hell. I honestly spiked to about 36-38 psi 3 times on 3 partial pulls when I had some mapping issues with EcuFlash. That probably produced a torque spike of ~500 lb-ft which weakened one of the rods.
Oddly, the failure happened in 5th gear under 1/2 throttle while passing somebody going under the speed limit on I-29. I would convert back to stock and make the dealer fix it, but I honestly don't want another stock block that is incapable of handling a decent 450-500 WHP.
No tuning issues. 2-3 counts of knock max. 11.6 AFR with a large shot of methanol/water. Very conservative timing. 30-32 psi straight across from 3500 to 7500 rpm.
Must have just been too much for the stock bottom end to handle. *shrugs*
I'll find out soon if it was rod bolt failure, but it honestly doesn't look like that is the case. Nor should it have been because I neither make much torque nor rev past 7600 rpm.
edit: There are my modifications:
CBRD BB-X turbo, ported exhaust manifold & turbine housing, Invidia DP/TP/N1 catback, Cobb Intake + Inlet hose
Custom UICP, Snow Performance CH3OH/H2O injection, AMS inline fuel pump, 1000 cc/min DW injectors, Cossy fuel rail (doesn't matter, but just illustrating the adequacy of my fuel system), replaced OEM fuel relay w/ green one
Exact thing happened to me. Perfect AFR, no knock, good pulls previous to breakage but with 50hp less. I guess you are swimming in your own **** now? That's too bad.
Last edited by DRAG; Jan 25, 2010 at 02:53 PM.
1. 12,000
2. No symptoms. Good AFR, no knock, car ran fine with 50hp less. Immediate carnage when it occured on a clean pull.
3. Stock rods broke clean in half, 2 of them in the same location. It was not a rod bolt failure in my opinion as one of the broken rods had a clean break and the rod bolts remained in tact. The bearings on that cylinder were "ok" as well.
Mods:
Turboback exhaust, Cobb AP, 200 shot of nitrous wet, 110 octane. Car ran 11s before the shot. I can only imagine that the 700+wtq @ 4000rpm caused the rod to break.
2. No symptoms. Good AFR, no knock, car ran fine with 50hp less. Immediate carnage when it occured on a clean pull.
3. Stock rods broke clean in half, 2 of them in the same location. It was not a rod bolt failure in my opinion as one of the broken rods had a clean break and the rod bolts remained in tact. The bearings on that cylinder were "ok" as well.
Mods:
Turboback exhaust, Cobb AP, 200 shot of nitrous wet, 110 octane. Car ran 11s before the shot. I can only imagine that the 700+wtq @ 4000rpm caused the rod to break.
What I dont understand is why you guys think a STOCK internals can handle all this. Nitrous, 30+ lbs of boost on stock internals, is rediculous. I say if your gonna push the power, atleast beef up the most important part of the car.
I couldn't agree more, but if guys like us weren't willing to push things a little then no one would ever know what they could or couldn't take right? I bought another stock motor and am building one for when I pop that one. I want another stab at going fast on the stock motor.
Evolved Member
Joined: Feb 2008
Posts: 1,571
Likes: 0
From: Rhode Island
I am a little confused here because DRAG in another post (https://www.evolutionm.net/forums/ev...-handle-7.html) provided his recommendations (he works in an engine building shop) regarding the limits of the OEM rods to be "100hp/cyl". Now assuming he meant wheel horsepower, I calculate that he was achieving ~473.5whp, i.e., >100whp/cyl, given his X's weight, trap speed and ET (3710, 116 and 11.4, respectivley) in his signature. So isn't a reasonable explanation for his and perhaps others failure be due to rod and or piston failure...or am I out of it here?
Later, Ken
Later, Ken
I am a little confused here because DRAG in another post (https://www.evolutionm.net/forums/ev...-handle-7.html) provided his recommendations (he works in an engine building shop) regarding the limits of the OEM rods to be "100hp/cyl". Now assuming he meant wheel horsepower, I calculate that he was achieving ~473.5whp, i.e., >100whp/cyl, given his X's weight, trap speed and ET (3710, 116 and 11.4, respectivley) in his signature. So isn't a reasonable explanation for his and perhaps others failure be due to rod and or piston failure...or am I out of it here?
Later, Ken
Later, Ken
My times in my signature are misleading. I ran 11.7 @ 116 on the stock turbo (93mph in the 1/8). My 11.4 pass was spraying a good size shot of nitrous and I went 103 in the 1/8th then hit the rev limiter in 4th which scared me pretty good on the spray...so I coasted to the 11.4. 7.2 @ 103 should work out to a 10 second pass around 130 or so...but that would be bench racing
1. 6300 miles
2. Big cloud of smoke, loss of oil pressure and power, a quart of oil spewing out of my tail pipe
3. Drag racing, ring land failure on #4 psiton...No logged knocks unitl after the incident. Still rolled to 12.0 @ 86mph
2. Big cloud of smoke, loss of oil pressure and power, a quart of oil spewing out of my tail pipe
3. Drag racing, ring land failure on #4 psiton...No logged knocks unitl after the incident. Still rolled to 12.0 @ 86mph
What mods did you have when you blew?
Why can detonation not cause a rod failure if the rod is weakened over time?
This is not to say that your particular case was one significant knock event but knock can cause a rod failure.
Why can detonation not cause a rod failure if the rod is weakened over time?
This is not to say that your particular case was one significant knock event but knock can cause a rod failure.
EvoM Guru
iTrader: (50)
Joined: Mar 2006
Posts: 9,675
Likes: 132
From: Tri-Cities, WA // Portland, OR
And the other three pistons are ok, or do they have a lesser amount of damage? If its just piston #4, seems kinda strange that it would be the only one to toast.
