What is the limit of the stock block?
May 6, 2009, 06:22 AM
#46
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The 4b11 is newer, however we have disassembled and analyzed a few. The block is durable to an extent, however the way the pistons are set up from the factory will not allow reliable power to be extracted from it before the piston tops break off.
The 4b11 pistons are set up for low emissions, not high boost performance. It is very tight.
The 4b11 is newer, however we have disassembled and analyzed a few. The block is durable to an extent, however the way the pistons are set up from the factory will not allow reliable power to be extracted from it before the piston tops break off.
The 4b11 pistons are set up for low emissions, not high boost performance. It is very tight.
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
May 6, 2009, 06:35 AM
#47
Thank you for finally posting this
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
And useful info is now coming out! Thanks for your info.
May 6, 2009, 07:39 AM
#48
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Thank you for finally posting this
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
I've wondered that myself , it seems that many are having issues that we find hard to believe based on our testing . I know that a sensor which I saw before the car came out is no longer in the motor so I've wondered what else never made it on ? We have a customer with an upgraded turbo running around for the last few months running 25lbs and spiking higher with no issues and this guys races just about ANYTHING he can find on the road . For example I just swapped out my transmission and the new unit feels nothing like what I had on my car when I got it . I've been talking to many guys out there trying to get a good understanding of the car and your post again brings up a question which I've wondered about .
May 6, 2009, 07:46 AM
#49
Thank you for finally posting this
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
were you tuned when this happened?
28psi-spike 4th-gear in traffic, i hope every ones ok
Last edited by bbyevo8u; May 6, 2009 at 11:51 AM.
May 6, 2009, 08:00 AM
#50
Thank you for finally posting this
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
I lost the top of one of my pistons shortly after going to the upgraded turbo, all it took was a 28psi boost spike when I lugged it from 3,000 rpm in 4th gear when trying to squeeze into a gap in traffic one afternoon. Car continued to run fine. though it did lock down on me two day in a row while trying to crank it in the morning. Finally bent a valve due to cracked chunk working it's way loose on the dyno.
I know I'm not the only one to have this type of failure. I'm starting to wounder if mitsu did not change something mid production that would account for why some of us have the issue and other do not, despite the fact that they are throwing stupid boost levels at the stock internals.
Scott, would you say the issue is more related to ring gaps or compressed ring stack or not enough meat on the ringland?
Usually the symptom of this is one of the spark plugs grounding strap will become bridged as the piece of the piston hammers it shut.
Pulling out the plug and opening it up usually gets the car running correctly again, but it will continue to re-occur over time.
There is not too much to look forward to because if you are lucky enough to have the piston top make its way out of the exhaust valves unscathed, the next stop is the turbine blades.
The piston schrapnel makes its way into the turbine blades, taking a few of them with it on its way out of the exhaust.
Fun times.
Last edited by TTP Engineering; May 6, 2009 at 08:13 AM.
May 6, 2009, 08:29 AM
#51
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At what torque level?
There is a significant difference in 600whp with say 550wtq and 600whp with say 450wtq. Would you not agree?
As I said before it's torque that kills motors. Torque is the actual force that your motor is providing. which is what strains the components, not not the measure of said force over time, which is what your measuring with Horsepower.
There is a significant difference in 600whp with say 550wtq and 600whp with say 450wtq. Would you not agree?
As I said before it's torque that kills motors. Torque is the actual force that your motor is providing. which is what strains the components, not not the measure of said force over time, which is what your measuring with Horsepower.
TTP-----Bump for answer please guys?
4B11 torque limt at your 600-700whp speculation?
May 6, 2009, 08:45 AM
#52
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The ring end gaps are set too close. High boost forces them closer together until they touch each other and one of the ends breaks off and takes a piece of the piston top with it.
Usually the symptom of this is one of the spark plugs grounding strap will become bridged as the piece of the piston hammers it shut.
Pulling out the plug and opening it up usually gets the car running correctly again, but it will continue to re-occur over time.
There is not too much to look forward to because if you are lucky enough to have the piston top make its way out of the exhaust valves unscathed, the next stop is the turbine blades.
The piston schrapnel makes its way into the turbine blades, taking a few of them with it on its way out of the exhaust.
Fun times.
Usually the symptom of this is one of the spark plugs grounding strap will become bridged as the piece of the piston hammers it shut.
Pulling out the plug and opening it up usually gets the car running correctly again, but it will continue to re-occur over time.
There is not too much to look forward to because if you are lucky enough to have the piston top make its way out of the exhaust valves unscathed, the next stop is the turbine blades.
The piston schrapnel makes its way into the turbine blades, taking a few of them with it on its way out of the exhaust.
Fun times.
May 6, 2009, 10:15 AM
#55
The ring end gaps are set too close. High boost forces them closer together until they touch each other and one of the ends breaks off and takes a piece of the piston top with it.
Usually the symptom of this is one of the spark plugs grounding strap will become bridged as the piece of the piston hammers it shut.
Pulling out the plug and opening it up usually gets the car running correctly again, but it will continue to re-occur over time.
There is not too much to look forward to because if you are lucky enough to have the piston top make its way out of the exhaust valves unscathed, the next stop is the turbine blades.
The piston schrapnel makes its way into the turbine blades, taking a few of them with it on its way out of the exhaust.
Fun times.
Usually the symptom of this is one of the spark plugs grounding strap will become bridged as the piece of the piston hammers it shut.
Pulling out the plug and opening it up usually gets the car running correctly again, but it will continue to re-occur over time.
There is not too much to look forward to because if you are lucky enough to have the piston top make its way out of the exhaust valves unscathed, the next stop is the turbine blades.
The piston schrapnel makes its way into the turbine blades, taking a few of them with it on its way out of the exhaust.
Fun times.
This lines up bang on what we saw in my friend's car. He's a good, conservative tuner, and I believe its from a boost spike.
Thank you so much for coming forward with this info, it is really valueable info for the community at large, but it makes me feel uncomfortable about my power goals and I've revised them down somewhat.
Do you have plans on how to tackle this for a bigger turbo application? I want to be able to run that new 3076R Garrett kit, but don't want to chip off the tops of my pistons if I run 30psi and the ring gaps cause that degree of damage.
May 6, 2009, 10:29 AM
#56
This lines up bang on what we saw in my friend's car. He's a good, conservative tuner, and I believe its from a boost spike.
Thank you so much for coming forward with this info, it is really valueable info for the community at large, but it makes me feel uncomfortable about my power goals and I've revised them down somewhat.
Do you have plans on how to tackle this for a bigger turbo application? I want to be able to run that new 3076R Garrett kit, but don't want to chip off the tops of my pistons if I run 30psi and the ring gaps cause that degree of damage.
Thank you so much for coming forward with this info, it is really valueable info for the community at large, but it makes me feel uncomfortable about my power goals and I've revised them down somewhat.
Do you have plans on how to tackle this for a bigger turbo application? I want to be able to run that new 3076R Garrett kit, but don't want to chip off the tops of my pistons if I run 30psi and the ring gaps cause that degree of damage.
The other end of the equation is the piston to wall clearances. This has not yet been a notable factor as of yet because 9/10 times the rings break before the piston skirt scuffs up the wall. Nevertheless at some point, sooner than on the 4g63, the piston will touchdown on the cylinder bores and score them up, leading to ring seal compromise and cylinder compression dropping. When cylinder pressure drops, power output drops and the engine health deteriorates quickly.
At the current time, removing the pistons and re-setting the piston ring end gaps may be a temporary fix, however the amount of work required and the level of risk involved in screwing something up in re-assembly is very favorable.
With the amount of work involved in this project, one may consider just building the engine with forged pistons and rods.
May 6, 2009, 10:36 AM
#57
Here is a video demonstrating what happens when the piston rind end gaps collide.
http://qik.com/video/1619810
The difference in the mockup video is that while in a piston the rings have no where to go so they cannot pass each other like the video. The only place they can go while in the rail of the piston slot is directly at each other. Once they touch, force continues to build until it can be released though popping the top off of the piston.
http://qik.com/video/1619810
The difference in the mockup video is that while in a piston the rings have no where to go so they cannot pass each other like the video. The only place they can go while in the rail of the piston slot is directly at each other. Once they touch, force continues to build until it can be released though popping the top off of the piston.
May 6, 2009, 11:23 AM
#58
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Man, that looks real similar to how mine failed. The last pull on the dyno a chunk hit the plug and bent the electrode to the side and then I can only assume tweaked a valve. Shut it down and did a comp test and had no comp on #1. Car went off to the dealer latter that day and I never got the damaged piston back (mitsu wanted it back).
In the beginning people were looking at mine saying it had deted, but there was no det pitting, just some gouges from the chunks bouncing around in the cylinder. I knew it was not a tuning issue and something else had to have been going on.
I'll see if I can find the pics of the pistons on mine.
I got lucky in that nothing got out the exhaust valve, my shinny new turbo was still shinny and new
Also my dealer was real cool and got me hooked up with a new block, head, valves, etc and installed my ross pistons and manley rods for me.
Just waiting on the timing chain tool to do the cam install now
In the beginning people were looking at mine saying it had deted, but there was no det pitting, just some gouges from the chunks bouncing around in the cylinder. I knew it was not a tuning issue and something else had to have been going on.
I'll see if I can find the pics of the pistons on mine.
I got lucky in that nothing got out the exhaust valve, my shinny new turbo was still shinny and new
Also my dealer was real cool and got me hooked up with a new block, head, valves, etc and installed my ross pistons and manley rods for me.Just waiting on the timing chain tool to do the cam install now
Last edited by Mad_SB; May 6, 2009 at 11:38 AM.
May 6, 2009, 11:29 AM
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stupid stop and go traffic in atlanta, sometimes you just gotta GO when you can
At the time I did not notice anything unusual, it was only when I hit the peak hold button latter and noticed the 28psi spike, and then the engine locking down while I was cranking it a couple mornings latter.