Analyzing a critical engine flaw in the 4b11 by TTP
Mar 17, 2010, 11:03 PM
#33
You give me a 100% stock car mechanically, and I can grenade that engine pretty damn quick with an improper tune or crap gas.
Generally, OEMs spend hundreds of hours endurance testing. They don't come up with the specs out of thin air. I will say that there are times they mess up; i.e. any recall. Nissan Titan overheating the trannies, previous gen Mazdaspeed 3 having engine mount failures, all the problems with the 2003 Evos, late 90s Ford Taurus cracking engine block in 60k miles, pintos blowing up, etc.
Anybody want to look up the spec for ring gap on the Evo IX 4G63? Take into account the different bore size. How about a GM Ecotec? Or Honda K20?
Mar 17, 2010, 11:14 PM
#36
So the 4B11t is 0.02mm tighter than the 4G63 on ring #1. They're essentially the same though over the specificed range. Granted, the 4G63 has a slightly smaller bore.
Also, something else to think about, I think most 'aftermarket' piston ring gap specs are based on using forged pistons. Forged pistons have a different thermal expansion rate than cast pistons, reason why you have to spec your wall clearances differently.
Also, something else to think about, I think most 'aftermarket' piston ring gap specs are based on using forged pistons. Forged pistons have a different thermal expansion rate than cast pistons, reason why you have to spec your wall clearances differently.
Mar 17, 2010, 11:49 PM
#38
First you have to establish what is an acceptable gap.
Do we believe the 0.004" per inch of bore? - if we do then yes the 0.007" MIN range is bad
Personally I hope the guy that built my engine was slack and left 0.011 gaps
hehe
The BIG problem is that this probably only occurs on modified cars... In which case Mitsubishi has no case to answer for.
It's just unfortunate that the 4b11 is less enthusiast friendly (vs the 4g63)
Do we believe the 0.004" per inch of bore? - if we do then yes the 0.007" MIN range is bad
Personally I hope the guy that built my engine was slack and left 0.011 gaps
heheThe BIG problem is that this probably only occurs on modified cars... In which case Mitsubishi has no case to answer for.
It's just unfortunate that the 4b11 is less enthusiast friendly (vs the 4g63)
Mar 17, 2010, 11:55 PM
#39
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Please post your sample of cars that led to your conclusions.
How many cars? If this is only a handful of cars, it's hardly a large enough sample to extrapolate out to all Xs produced.
What state of modification were they in? Heavily modded? Stock?
Were they properly tuned for their mods? There have been a handful of documented engine failures that are 100% from not being tuned properly.
Did the failure(s) happen during racing? Or were these daily driven cars?
Too much information isn't shared to know if this is truly a widespread issue that would cause all Evo X owners to worry, or if these are isolated incidents to certain cars with certain mods.
How many cars? If this is only a handful of cars, it's hardly a large enough sample to extrapolate out to all Xs produced.
What state of modification were they in? Heavily modded? Stock?
Were they properly tuned for their mods? There have been a handful of documented engine failures that are 100% from not being tuned properly.
Did the failure(s) happen during racing? Or were these daily driven cars?
Too much information isn't shared to know if this is truly a widespread issue that would cause all Evo X owners to worry, or if these are isolated incidents to certain cars with certain mods.
So say with any stock evo 8 , you up the boost by + 10 psi more , can you honestly say thats not gonna cause problems elsewhere in the tune? its not mitsu's fault , they built the car for that boost with that gas and that tune...when you modify for more power you have to take responsibility in errors and damage...Nonetheless Im very interested in seeing stock x engines with this issue , I havent came across any as of yet but being a tech it'd be helpful knowledge
As far as ring gap , its mainly emissions and a little extra power , its not uncommon to see that tight of a gap on turbo vehicles in this era ...the epa doesnt want smoke blowing turbo engines on the roads , standards get stricter by the year and boost goes up as well what other road would they take ?
Mar 18, 2010, 12:17 AM
#41
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...Mitsubishi wont risk a leaner tune for them longevity isnt a big deal with stock unmodified cars and they dont care if you break it and they know you did ...everythings about warranty claims
Mar 18, 2010, 12:23 AM
#42
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lol I agree a leaner tune would do the same..but with a greater percent of engine damage should someone mess up, they want it fat but with tighter rings to keep blowby trapped and burned, maybe they need to redesign the egr/evap system and loosen the rings ,lol
...Mitsubishi wont risk a leaner tune for them longevity isnt a big deal with stock unmodified cars and they dont care if you break it and they know you did ...everythings about warranty claims
...Mitsubishi wont risk a leaner tune for them longevity isnt a big deal with stock unmodified cars and they dont care if you break it and they know you did ...everythings about warranty claims
Come on man my car off the show room floor was so damn rich it would choke it's self in fuel. No reason a stock car should get afr's into the 9's
