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For what it is worth, Carrillo's engineers disagree with you on a couple of points.
They say connecting rods, in correctly assembled naturally aspirated engines fail on the exhaust stroke, because there is't any resistance on the piston as it reverses direction. Turbocharged engines have back pressure on this stroke and are very easy on connecting rods.
Makes sense, to me.
They also say that the vast majority of naturally aspirated race engine failures (again, correctly assembled and not from an oiling failure) are from knock (detonation.)
The rod bearings were not a factor in the first failure. I have not seen either the failed rod or the bearings from the second engine.
There's a MAJOR difference in the two failures. In the first failure, the wrist pin was still in the piston, In the second failure, the wrist pin has been ripped out of the piston.
Carrillo's engineers disagree with you on some key points.
They say connecting rods, in naturally aspirated engines fail on the exhaust stroke, because there is't any resistance on the piston as it reverses direction. Turbocharged engines have back pressure on this stroke and are very easy on connecting rods.
They also say that the vast majority of naturally aspirated race engine failures are from knock (detonation.)
I don’t think that the first point is inconsistent with what I wrote. The rods fail under tension, and tension is greatest at TDC of the exhaust stroke end during the overlap. Throttle closed downshift is the riskiest situation. Turbo has back pressure alright, but by logic it doesn’t really help during downshifts, in my opinion.
In my opinion, detonation will lead to rod failure, but only indirectly. Detonation will damage rod bearings, and the rod bearing failure leads to rod failure. What I was writing about is direct rod failure that wasn’t preceded by a spun rod bearing. Probably wasn’t clear enough about what I meant.
by the way, curious, in reference to what Erik said, why are turbo'ed motors easier on rod bearings?
Per hp overall, turbo motors are much easier on the rods than n/a motors. That’s because the turbo engine need not be spun as high to make the power. A stock 1987 S4 engine wants to make a reasonably reliable 600 rwhp at 6000 rpm without any internal engine modifications, once you bolt on the turbos.
Per peak torque and under compression it’s about the same, but the turbo motor can have 2-3x the torque so clearly turbo motors end up needing more strength under compression.
For most low boost and n/a engines, the tension load is what is the binding requirement and rods don’t usually buckle under compression. High boost turbo diesels are all about rod strength under compression.
Focusing on tension loads, with throttle open, turbo engine has pressure inside the combustion chamber that reduces the tension load and thus the rod strength requirement. That’s a meaningful but not a very large effect. And during throttle closed downshift, turbo and n/a engine have about the same tension loads on the rod, for the same stroke, rpm, and component weights. Usually turbo pistons are little heavier, so that’s one thing to take into account too.
There are obvious advantages to more modern injection systems versus the old Bosch injection used on these two engines.
The ability to gather data is high on that list.
The very first thing that any engine builder or engine component supplier wants to see is recorded RPM data.
It only takes one missed shift or overreved downshift to damage an engine and have a catastrophic failure.
The engineers at Carrillo just rolls their eyes and shrugs their shoulders when I hand them the lower portion (all that is left) of a broken rod, when I have no recorded rpm data.
Failure analysis is very limited without any clues.
Both sets of these rods were created at the same time...and certainly there could have been an unseen flaw in the forgings that also did not show up under MagnaFlux inspectiion, when manufactured. Intense inspection of the remaining 7 rods showed no flaws or any changes in dimension....as a matter of fact, six of the remaining rods were used in another engine, without reconditioning them (the seventh rod had "cosmetic damage" from being next to the rod that failed.....we probably still have it.)
The fact that the piston pin remained in the first failure, would certainly lead one to the conclusion that the "strap" of the rod (the piece of the rod above the wrist pin) failed....anything that happened after the initial failure would make "removal" of the pin end of the rod from the wrist pin highly unlikely.
As I mentioned, this failure is completely different, in that the wrist pin was ripped out of the piston, pointing to pin failure or piston failure.
Perhaps worth noting, the pistons in each of these engines were completely different. The first engine had 968 pistons. The second engine had CP pistons, with smaller diameter wrist pins than the 968 version had.
One huge thing that hasn't been even touched upon is matching rpms on downshifts. The failure to do this is terribly hard on both transmissions and engines.
In the engine, sudden slowing of the crankshaft by the transmission, without matching engine rpms is literally trying to pull the piston off of the crankshaft. Very large forces are "absorbed" by the wrist pin and the connecting rod in these instances.
Vehicles with higher "splits" between gears (928s) suffer much more from this problem.
Some drivers have long term issues with not matching rpms on downshifts....and will have a long history of engine and transmission failures. LONG HISTORY....MANY BROKEN TRANSMISSIONS AND ENGINES.
Again, rpm data from the lap leading up to this failure would be almost a requirement in any sort of failure analysis, I'm guessing. It's worth noting that both failures of these engines occurred at virtually the same exact point on the track, which is proceeded by a section of the track requiring radical slowing and downshifting. Both of these engines failed at the first full load, full rpm point after the downshifting section.
And a final note, gathered from many, many hours of Sharktuning. 928 knock sensors on highly tuned engines, will almost always "go off" under high rpm throttle closing. While I"ve always considered this to be just a "glitch" in the process, I've become aware that this "knock" might be a real event in a very hot, very lean combustion chamber.
What forces are imparted onto a piston and connecting rod when a high rpm downshift occurs (without rpm matching), combined with a knock event thrown into the mix, is way, way beyond my knowledge.
Can't argue with the need for some method for verifying the peak rpms that the engine saw. If it's a racing tach, you'd think it would have a peak rpm memory or even just a needle telling the tale.
One would think that the impact of downshifts on the rod and piston assembly would be almost completely be captured by the rpm. If the rpms don't match, then I am sure that it's hard on clutch, transmission, and the rest of the driveline. But I don't see an obvious physics based reason why anything but the rpm would really matter to the rod and piston assembly in that situations. Either revs go above the redline or they don't.
Whether the throttle-closed knock is real or detection error (my guess is that it's a detection error), it's largely irrelevant. That's because with the throttle closed, there simply isn't enough air in the cylinder after a couple of revolutions to do any damage to the engine. Just not enough energy. That's why the knock detection systems, good ones anyway, measure not just occurrence but also intensity of knock.
High intensity knock causes compression load, and by my understanding that's not how the rods failed here. They didn't buckle. So to the extent that the knock is relevant, it's because it has pounded the bearing and caused a bearing failure before the rod failed. The bearings for all the cylinders, not just the one with a failed rod, might be informative.
Another thing is that each engine has it's octane requirement. If the hypothesis is that the fuel was wrong, then the first thing to do would be to think about the octane requirement of the engine. Relevant factors are 104mm bore, all aluminum engine, 4-valve pent roof head, 11.5:1 geometric compression, cold air intake, probably about 100% volumetric efficiency, long-tube headers, and big intake cam. This pure speculation on my part, but given that GTS has 10.4:1 from the factory with exhaust manifolds and small intake cam, 11.5:1 doesn't seem like that high of a geometric compression ratio that would require very high octane fuel. We're certainly giving a lot of boost to these 9.4:1 and 10:1 S4s and GTs without knock.
It's in my opinion completely valid procedure to mix fuels of different octane ratings to produce the chosen fuel octane, as long as that chosen fuel octane is above the octane requirement of the engine.
One thing that I found initially counter-intuitive is that a larger diameter pin can be made lighter than a smaller diameter pin, given the same required ability to hold load. So if there's enough compression height and room, large diameter pin is often the way to go. Of course, in a clean sheet design engine, one could lower the deck height and make the engine smaller by reducing compression height and rod length, so the car factories have been reducing the piston wrist pin diameters over the years.
The GT3's running that kind of compression were designed for it an account for that in material selection, cam profiles, way more advanced knock detection among other things like DIRECT INJECTION.
Hell, Mazda runs 14:1 compression with 87 octane in their standard Miatas.
We are pushing these engines beyond their designed factory outputs and limitations. You saw the plugs with little ***** of melted metal on them in this thread.
The engines were running too hot, in this case, too low of an octane for the compression ratio as the AFRs were fine. The engines knocked enough to crack a rod and cause a catastrophic failure. This was from not running the correct octane fuel.
This isn't about rod design at this point as any rod would have failed in those conditions. It's about running an engine outside of its intended operating conditions.
well, mark had a 50/50 mix of 110 and 91 octane so it should have been ok. ive never said its about the rod strength, as it seems obvious, the rod didnt break first, it couldnt have. the rod had to be in one piece so that it could PULL the wrist pin OUT of the piston. so i think we all agree its not a rod issue. as far as little *****..........i had something that looked like this on my ground strap, and it turned out to be powder residue, not aluminum *****. this is easy to verify by taking a scalple to the plug under magnification and see if it turns to dust as mine did.
Originally Posted by GregBBRD
Mark:
Like I said, ignore until you say something completely stupid, again.
From the above statement, I know you have no idea how much .060" looks like, in your head.
.060" is the thickness of an American quarter!
When the rod is off .060", the "short" side dimension will actually be touching the piston pin boss!!!!!
Every single engine that I built for Mark Anderson, before his last engine, used "Chevy offset" connecting rods....supplied by Mark Anderson. On every single previous engine, I had to machine the inside of the piston boss, on the "short side", so the connecting rod did not rub on the piston boss!
The picture you keep referring to, isn't anywhere near .060" off! It simply off from the perspective of where the picture was taken from.
Greg, I ALREADY MOVED THE PIN 0.60" for you to see what it looks like... it looks identical to the piston , pin position in the picture. and you can see its not PERSPECTIVE, ...........you are sounding like a flat earther now! yes, i measured something that was .060" and moved the piston small end off center by that amout....
THEN, you talk about anderson giving you chevy offset rods.... you said no one ever did that, so im confused. corillo made 928 rods with the correct offset with 928 bearings...... now you are saying they made chevy rods witih the 928 bearings? a little confused here. if you had to machine the piston boss, that wouldnt chagne the fact that the piston was off center by some large amount.. as you can see by my pictures of a stock 928 piston, when i move the piston 0.060", there is about .030" still left to the side of the piston before contact.
Originally Posted by GregBBRD
For what it is worth, Carrillo's engineers disagree with you on a couple of points.
They say connecting rods, in correctly assembled naturally aspirated engines fail on the exhaust stroke, because there is't any resistance on the piston as it reverses direction. Turbocharged engines have back pressure on this stroke and are very easy on connecting rods.
Makes sense, to me.
They also say that the vast majority of naturally aspirated race engine failures (again, correctly assembled and not from an oiling failure) are from knock (detonation.)
The rod bearings were not a factor in the first failure. I have not seen either the failed rod or the bearings from the second engine.
There's a MAJOR difference in the two failures. In the first failure, the wrist pin was still in the piston, In the second failure, the wrist pin has been ripped out of the piston.
why would having back pressure on the way up , make it any less stressful on the connecting rod.. the previous stroke up is a compression stroke which is maybe less force on a turbo due to less compression ratio, but the forces downward on that piston on the power downstroke would be orders of magnitude more . so, im confused here . what are you saying , or how do you understand it??
the fact that the wrist pin was still in the first motor, doesnt meant the rod was the cause of failure, it just means that the rod pin in the piston might have been stronger than the weakest point of the rods, near the small end to fail as the piston was beign pulled down. ceretainly the case with FANS engine, showing that the rod would have to be in one piece to pull the wrist pin out of the piston. in Mark As engine, if the cause was the same, it just broke at a weaker "link in the chain". was marks engine failure engine due to detonation damage in your opinion?
That is some great information there, as you know, im a HUGE proponent of rev matching, and knowledgeable in the forces that can be transferred to the engine, short shafts and other pre-gearing components. Many argued with me on the point, until you start doing the math. anything past 3-4th gear has enough of a multiplied force factor to do some real damage to the clutch, short shaft and engine components.... sure, this could be a potential problem, but as we have seen from the video, there were no unusual downshifts or RPM climbs.... however, im not certain of that.. ill have to watch it again. there are things that could be well beyond our hearing of the sounds in the video, ill agree. BUT, if overrev forces were the issue, wouldnt it break the smallest part of the rod,not the FATTEST/strongest part of the rod???
In both engines, a piston failure, either by detonation (ring failure, or piston cracking) or side loading (offset issue), would stop in the bore and then the rod woudl be pulled out of the piston. where it breaks is anyone's guess. pull the pin out of the piston or a broken rod at the smallend or at the top of the rod....... either way, that could be due to piston failure first. if the rod failed near the top as in Mark's engine and there was no piston damage to cause it, certainly it could be caused by overrev or misshift.
Originally Posted by GregBBRD
There are obvious advantages to more modern injection systems versus the old Bosch injection used on these two engines.
The ability to gather data is high on that list.
The very first thing that any engine builder or engine component supplier wants to see is recorded RPM data.
It only takes one missed shift or overreved downshift to damage an engine and have a catastrophic failure.
The engineers at Carrillo just rolls their eyes and shrugs their shoulders when I hand them the lower portion (all that is left) of a broken rod, when I have no recorded rpm data.
Failure analysis is very limited without any clues.
Both sets of these rods were created at the same time...and certainly there could have been an unseen flaw in the forgings that also did not show up under MagnaFlux inspectiion, when manufactured. Intense inspection of the remaining 7 rods showed no flaws or any changes in dimension....as a matter of fact, six of the remaining rods were used in another engine, without reconditioning them (the seventh rod had "cosmetic damage" from being next to the rod that failed.....we probably still have it.)
The fact that the piston pin remained in the first failure, would certainly lead one to the conclusion that the "strap" of the rod (the piece of the rod above the wrist pin) failed....anything that happened after the initial failure would make "removal" of the pin end of the rod from the wrist pin highly unlikely.
As I mentioned, this failure is completely different, in that the wrist pin was ripped out of the piston, pointing to pin failure or piston failure.
Perhaps worth noting, the pistons in each of these engines were completely different. The first engine had 968 pistons. The second engine had CP pistons, with smaller diameter wrist pins than the 968 version had.
One huge thing that hasn't been even touched upon is matching rpms on downshifts. The failure to do this is terribly hard on both transmissions and engines.
In the engine, sudden slowing of the crankshaft by the transmission, without matching engine rpms is literally trying to pull the piston off of the crankshaft. Very large forces are "absorbed" by the wrist pin and the connecting rod in these instances.
Vehicles with higher "splits" between gears (928s) suffer much more from this problem.
Some drivers have long term issues with not matching rpms on downshifts....and will have a long history of engine and transmission failures. LONG HISTORY....MANY BROKEN TRANSMISSIONS AND ENGINES.
Again, rpm data from the lap leading up to this failure would be almost a requirement in any sort of failure analysis, I'm guessing. It's worth noting that both failures of these engines occurred at virtually the same exact point on the track, which is proceeded by a section of the track requiring radical slowing and downshifting. Both of these engines failed at the first full load, full rpm point after the downshifting section.
And a final note, gathered from many, many hours of Sharktuning. 928 knock sensors on highly tuned engines, will almost always "go off" under high rpm throttle closing. While I"ve always considered this to be just a "glitch" in the process, I've become aware that this "knock" might be a real event in a very hot, very lean combustion chamber.
What forces are imparted onto a piston and connecting rod when a high rpm downshift occurs (without rpm matching), combined with a knock event thrown into the mix, is way, way beyond my knowledge.
Can't argue with the need for some method for verifying the peak rpms that the engine saw. If it's a racing tach, you'd think it would have a peak rpm memory or even just a needle telling the tale.
One would think that the impact of downshifts on the rod and piston assembly would be almost completely be captured by the rpm. If the rpms don't match, then I am sure that it's hard on clutch, transmission, and the rest of the driveline. But I don't see an obvious physics based reason why anything but the rpm would really matter to the rod and piston assembly in that situations. Either revs go above the redline or they don't.
Whether the throttle-closed knock is real or detection error (my guess is that it's a detection error), it's largely irrelevant. That's because with the throttle closed, there simply isn't enough air in the cylinder after a couple of revolutions to do any damage to the engine. Just not enough energy. That's why the knock detection systems, good ones anyway, measure not just occurrence but also intensity of knock.
High intensity knock causes compression load, and by my understanding that's not how the rods failed here. They didn't buckle. So to the extent that the knock is relevant, it's because it has pounded the bearing and caused a bearing failure before the rod failed. The bearings for all the cylinders, not just the one with a failed rod, might be informative.
Another thing is that each engine has it's octane requirement. If the hypothesis is that the fuel was wrong, then the first thing to do would be to think about the octane requirement of the engine. Relevant factors are 104mm bore, all aluminum engine, 4-valve pent roof head, 11.5:1 geometric compression, cold air intake, probably about 100% volumetric efficiency, long-tube headers, and big intake cam. This pure speculation on my part, but given that GTS has 10.4:1 from the factory with exhaust manifolds and small intake cam, 11.5:1 doesn't seem like that high of a geometric compression ratio that would require very high octane fuel. We're certainly giving a lot of boost to these 9.4:1 and 10:1 S4s and GTs without knock.
It's in my opinion completely valid procedure to mix fuels of different octane ratings to produce the chosen fuel octane, as long as that chosen fuel octane is above the octane requirement of the engine.
One thing that I found initially counter-intuitive is that a larger diameter pin can be made lighter than a smaller diameter pin, given the same required ability to hold load. So if there's enough compression height and room, large diameter pin is often the way to go. Of course, in a clean sheet design engine, one could lower the deck height and make the engine smaller by reducing compression height and rod length, so the car factories have been reducing the piston wrist pin diameters over the years.
you are missing the fact that , the reverse calculation of the gear ratio splits have LITTLE to do with the actual RPM, but the rate of change of RPM. the transmission being mis-shifted from 5th to 4th can create accelerations because of the force on the piston, far in excess of what can be achieved under WOT conditions, and high rpm values alone.
i totally agree with you on the "off throttle " "knock".. no, greg seems to forget that many engines can run very well at "lean of stoich" at 75% power settings. its not the lean that makes detonation, its the STOICH that makes detonation. off throttle, doesnt have the mass flow, temps or mixture to make knocks....
Can't argue with the need for some method for verifying the peak rpms that the engine saw. If it's a racing tach, you'd think it would have a peak rpm memory or even just a needle telling the tale. Stock tachometer, stock Bosch engine management, The last time the tach would have been calibrated is when VDO assembled the cluster, 30 years ago. This is definitely a "weak link" in trying to figure out the failure mode.
One would think that the impact of downshifts on the rod and piston assembly would be almost completely be captured by the rpm. If the rpms don't match, then I am sure that it's hard on clutch, transmission, and the rest of the driveline. But I don't see an obvious physics based reason why anything but the rpm would really matter to the rod and piston assembly in that situations. Either revs go above the redline or they don't. There's more to it, than just rpms. Inertia and change in direction become a major factor. Pistons and rods, in normal operation, are "pushing" on the crankshaft. On a downshift with a high rpm delta (with long splits between gear ratios, like in a 928) the pistons are no longer driving the crankshaft. The crankshaft is being forced to slow down very quickly, by the gear ratios, which "pulls" on the connecting rods and pistons much harder. Think of it this way: The piston and rod normally have inertia in one direction (up), which is stopped and forced the other way (down) by the combustion process, in normal engine acceleration. If the crankshaft suddenly slows (from a non rpm matched downshift), the piston and rod have the exact same inertia (going up), but the crankshaft is instantaneously slowing....which pulls back on the rod and the piston.....radically. This almost doubles the forces on the connecting rod and the piston.
Whether the throttle-closed knock is real or detection error (my guess is that it's a detection error), it's largely irrelevant. That's because with the throttle closed, there simply isn't enough air in the cylinder after a couple of revolutions to do any damage to the engine. Just not enough energy. That's why the knock detection systems, good ones anyway, measure not just occurrence but also intensity of knock. Jim Corenman calls these events "transient knocks". They occur very quickly and disappear very quickly. I have no idea if they are "real" or not.
High intensity knock causes compression load, and by my understanding that's not how the rods failed here. They didn't buckle. So to the extent that the knock is relevant, it's because it has pounded the bearing and caused a bearing failure before the rod failed. The bearings for all the cylinders, not just the one with a failed rod, might be informative. Perhaps an incorrect conclusion. Actually, there is way too much of the connecting rod missing....to know the rod did not buckle. (The entire "beams' are gone.) And the piece remaining on the crankshaft is badly twisted, presumably from hitting other engine parts. The particular rod bearing I use is extremely robust....and as long as there is an oil film between it and the crankshaft, the rod could certainly buckle and the rod bearing could be unharmed.
Another thing is that each engine has it's octane requirement. If the hypothesis is that the fuel was wrong, then the first thing to do would be to think about the octane requirement of the engine. Relevant factors are 104mm bore, all aluminum engine, 4-valve pent roof head, 11.5:1 geometric compression, cold air intake, probably about 100% volumetric efficiency, long-tube headers, and big intake cam. This pure speculation on my part, but given that GTS has 10.4:1 from the factory with exhaust manifolds and small intake cam, 11.5:1 doesn't seem like that high of a geometric compression ratio that would require very high octane fuel. We're certainly giving a lot of boost to these 9.4:1 and 10:1 S4s and GTs without knock. Of course, the tuning of an engine determines the octane requirement. ("Octane" is a measurement of the ability of the fuel to not knock.) One can build a 8.5 to 1 engine and have knocks....Chevy and most of the rest of the engine makers virtually specialized in this, through most of the 1970's.......165hp 454 Chevy engines that knocked like there were hammers inside comes to mind.) This particular 928 engine was built with higher compression (way over 11.5 to 1) and tuned to run on pure race fuel. (My instructions, from Joseph were to make more horsepower from this engine. With the same intake, exhaust, cams, and heads....one becomes somewhat "limited" in the options to increase horsepower.)
It's in my opinion completely valid procedure to mix fuels of different octane ratings to produce the chosen fuel octane, as long as that chosen fuel octane is above the octane requirement of the engine. See above. The octane requirement of this engine was higher than any "mixture" of 91 octane street fuel could provide. I was not consulted about anything regarding this engine, once it left my shop, the first time.....several years ago. I did not maintain the engine....I actually never even saw the engine after I built it. Mark Anderson did not contact me about using this car. As a matter of fact, the car was already at Fontana and had blown a $10.00 used front tire before I was aware of it even being used. When Joseph used this car, he had the car transported and maintained at the track, by a race shop that specializes in providing this service. I'm assuming/hoping that these people weren't sending someone outside the track and down to the closest vendor of 91 octane street fuel, but used race fuel available at the track. (In my head, it seems that it would be more expensive to send someone out of the track and down to a local gas station to buy 91 octane street ****, than to just pay for race fuel.)
One thing that I found initially counter-intuitive is that a larger diameter pin can be made lighter than a smaller diameter pin, given the same required ability to hold load. So if there's enough compression height and room, large diameter pin is often the way to go. Of course, in a clean sheet design engine, one could lower the deck height and make the engine smaller by reducing compression height and rod length, so the car factories have been reducing the piston wrist pin diameters over the years. None of the piston pins used in these engines were "small" in an way, shape, or form. All of the pieces were extremely robust and engineered with a large safety margin. I might have mis-communicated in my last post about the pins. I was simply stating that they were different sizes to show that they were not the same exact pieces.
“BUT, if overrev forces were the issue, wouldnt it break the smallest part of the rod,not the FATTEST/strongest part of the rod???”
Kibort — Why do you think the fat part of the rod is fat and the skinny part of the rod is skinny? Think about how the weight of upstream beam contributes to the force.
Tuomo and I are way beyond your understanding of the internal combustion engine and your understanding of this failure. We are intelligently discussing theory and facts.
You, on the contrary, are like a dog with a bone....you can't get past the rod being centered on the piston pin....something that was solved before these engines were built. The rod built for these engines had the center line moved .065" (in comparison to an "old style" Small Block Chevy engine) to make them suitable for use in the 928 engine. (Go look up/measure the dimensional difference between the cylinder offset of a Small block Chevy engine and a Porsche 928 engine and figure this out, for yourself.)
It's centered. It's centered. It's centered. (Yours apparently, from what has been said, are not?)
This is for you, so you can go grab another bone to chew on.
These pictures are of the EXACT same rod and the EXACT same piston that are in Joseph's engine....pulled them off my shelf.
Here's a picture of the rod centered directly over the center of the piston and rod. Directly down the centerline:
Here's the same exact picture, taken from the same perspective of whoever shot the picture of Joseph's failed engine: (Looks kinda familiar, given only the change in perspective, right?)
Here's the same picture perspective, with the rod moved over .020" to compensate for crankshaft end play and rod clearance (on the big end.) (This engine has MORE play than this, but I'm not going to tell you how much. It's absolutely none of your business.) LOOK FAMILLIAR??? This is almost EXACTLY the same as your picture!!!
And here's a Chevy offset rod, shuffled over the same .020" to compensate for rod play and endplay:
Does this look anything like the picture you have? Can you even remotely imagine your picture looking like this?
I know that facts and accurate information confuses you, but give it up....you are completely, totally, 100% wrong!
first of all, you you fail perspective 101. no, those bottom pictures are NOTHING like the one in question. as i showed, i did 0.010, then 0.020" and then 0.060" in succession. you have to realize the total gap is .260" and half of that is 0.130" and if you have an incorrect offset, it can be off by 0.60". it looks exactly like i posted.
what you posted looks nothing like the original picture in angle, perspective, etc.
You also lied about the original rods... or maybe we misunderstood you.... mark A's rods were given to you with 928 offset and 928 bearings. they were NOT chevy rod offest and the fact that you say that you had to take an AXE to them and carve off the boss, tells me you are very confused. making room for an offset problem by grinding down the boss, doesnt change the offset problem.. or does it.
Mk
Originally Posted by GregBBRD
Mark:
This is for you, so you can go grab another bone to chew on.
These pictures are of the EXACT same rod and the EXACT same piston that are in Joseph's engine....pulled them off my shelf.
Here's a picture of the rod centered directly over the center of the piston and rod. Directly down the centerline:
Here's the same exact picture, taken from the same perspective of whoever shot the picture of Joseph's failed engine: (Looks kinda familiar, given only the change in perspective, right?)
Here's the same picture perspective, with the rod moved over .020" to compensate for crankshaft end play and rod clearance (on the big end.) (This engine has MORE play than this, but I'm not going to tell you how much. It's absolutely none of your business.) LOOK FAMILLIAR??? This is almost EXACTLY the same as your picture!!!
And here's a Chevy offset rod, shuffled over the same .020" to compensate for rod play and endplay:
Does this look anything like the picture you have? Can you even remotely imagine your picture looking like this?
I know that facts and accurate information confuses you, but give it up....you are completely, totally, 100% wrong!
You have any new bones to chew on?
Last edited by mark kibort; 06-24-2018 at 04:51 AM.
first of all, you you fail perspective 101. no, those bottom pictures are NOTHING like the one in question. as i showed, i did 0.010, then 0.020" and then 0.060" in succession. you have to realize the total gap is .260" and half of that is 0.130" and if you have an incorrect offset, it can be off by 0.60". it looks exactly like i posted.
what you posted looks nothing like the original picture in angle, perspective, etc.
You also lied about the original rods... or maybe we misunderstood you.... mark A's rods were given to you with 928 offset and 928 bearings. they were NOT chevy rod offest and the fact that you say that you had to take an AXE to them and carve off the boss, tells me you are very confused. making room for an offset problem by grinding down the boss, doesnt change the offset problem.. or does it.
Mk
Choose your words carefully. Calling me a liar will not turn out well, for you.
One more time, you incredibly stupid/stubborn human being:
Mark's engines had Chevy offset Oliver I beam connecting rods for many, many years. These were provided to me by Mark Anderson. In order to use these, one of the inside of the 968 piston bosses had to be machined so that the connecting rod would not rub on that piston boss. When the crankshaft for those rods became damaged, we used a different crankshaft with a Carrillo "A" beam Chevy offset rod. One of these rods failed in testing (not in Mark's engine) and I had Carrillo examine the rod. Their testing pointed out the problem with using the "long time" error (Thanks, Devek) of using Chevy offset connecting rods in a 928 engine...the report with the big words that you have had someone read to you. Carrillo build a "fresh sheet of paper" connecting rod for use in the 928 engine....for my use and for ANYONE that calls and orders a 928 connecting rod, from them. The first "prototype" rod was installed in an engine and carefully checked by both me and Carrillo for dimensional correctness. I recalled all of the engines I had assembled with the Chevy offset "A beam" connecting rods (including Mark Anderson's engine) and rebuilt those engines with the new design, properly designed, properly centered custom 928 connecting rods.
One of those rods failed in Mark Anderson's engine. The limited pieces from that rod (with ZERO engine data) and the remaining 7 rods were throughly examined by Carrillo, with ZERO design changes recommended.....I use that same exact connecting rod in my current engines and there are many,many of those rods in service! Carrillo's opinion (with ZERO engine data) was that the rod failed either from overreving the engine, or from knocking.
I seriously can't make this any clearer unless I come up and use your box of crayons to draw you pictures!
My God, boy, you are incredibly dense! If you haven't always been like this, you seriously should be checked for CTE damage during your "gladiator career". Did you play football, before that?
06-23-2018, 01:43 PM
yes, i measured something that was .060" and moved the piston small end off center by that amout.... 
