Isnt nearly all of his videos pointless,except for entertainment value? That makes critiquing his videos as if they were for engineering rather pointless,if not mild trolling.
I agree with this point. The main power is exerted when the rod is pushed. On the other hand one would assume, that more expensive cars are made with higher quality materials and components. I would like to know the weight of each item. I believe the old one is heavier and thicker than the others.
The rogue piston exiting a self-destructing tuned engine on a rolling road at maximum rpm may beg to differ! In almost all production engines, whether NA or forced induction, the highest stresses on a connecting rod are tensile, due to the inertia of the piston changing direction at the top of the exhaust stroke (no compression to reduce the tensile force). The rods in this test were from standard production engines, so the test is actually relevant. High boost engines, exotic fuel burners and engines suffering from detonation or hydraulic locking are possible exceptions to this general case, so top fuel drag racers, and diesel van drivers heroing it through 4 ft of flood water, for example, may count amongst those exceptions!
@@robair67 just what I was getting ready to say. most failures of the pin skirt or rod/bolts are tdc on the exhaust /intake stroke. rods bending are not near as common as stretch and bolt stretch.
Interesting part is the M3 the bolts did not give up, But yeah compression will be a better test since this rods get the blunt of the power stroke in compression
I agree. Internal forces are the other way. They push or compress the rod, not pull it. But that would not make for such a fun video because all those rod are more than adequate under normal operation. And actually the lighter the rod, the better it is for gas mileage
*Failure under compression* is a highly atypical failure mode, even for cast connecting rods. Failure usually takes place due to shearing forces in the wrist pin domain, poor lubrication at the big end bearings, or tensile forces on inadequately fastened rod caps. The highest loads on a connecting rod assembly are presented in tension from the reversal of momentum at the extremes of piston travel.
As a mechanical engineer I can say that this test shows only the tensile strength of the bolts not the connecting rods. Also compression strength is more important than tensile strength in the case of connecting rods because they are mostly exposed to compresion forces.
Only one failed 100% due to bolt failure. The first rod cap stretched until the bolts were subjected to forces in addition to the tension. The second failed due to the bolts. The third one was obviously not the rod bolts.
Tensile and fatigue failure are the most common failures of con rods and bolts. Compression failures are not common unless engine produce a lot of torque at low rpm such as diesels running large amounts of boost and fuel or adding nitrous at too low an rpm. I have removed plenty of rods from holes in the sides of engines. None were compression failures.
@@ziobrik 👍👍👍 4 strock engines: 3 strocks, the rod is compresed by: compresion, detonation, exhaust. 1 strock is admision when piston is pulled down by the rod freely with admision valve oppen. 👍👍👍
Yep, but they also suffer from tensile forces fue to the piston mass. Also the suffer lateral torsion too! Connecting rods are the MVP of the Engine team!
This isn't the only forces that the con rod faces.The piston It is a reciprocating mass after all. So when it changes direction at the end of the stroke, there is a significant amount of force involved.
Rods are always rated in Horsepower they can handle. That makes no sense. It's known that RPM and lower quality bolts (screws) is where they break - at the bolts.
For engineering purpose, technically you should have changed the M5 connecting rod at 5:03, cause results aren't accurate when a tensil trial fails. You can't do a second trail on an object that is already plastically deformed, because it will be falsing results.
if we're being that picky, the loading rate was controlled manually, and not very carefully in some cases. if they were measuring yield strength i would agree, but i can't see it making any difference to the UTS.
@@jamesg8246 they didn't understand what testing is. stockton - " 5" of carbonfibre. that'll do the trick." mexican employee - "but boss, shouldn't we do extensive testing on it?" stockton - "nah, it's got to get through 5" of carbonfibre, we'll put microphones on it so we can hear it cracking." mexican employee - "is it supposed to crack?" stockton - "there's 5" of it so who cares?" passenger - "i can hear cracking." stockton - "look, there's 5" of... " *radio silence*
Those old soviet cars were built to last and also in some of the toughest conditions. Not built for speed or high performance just a workhorse to get from A to B. Amazing to see. Thank you for the video.
I bet you never ever drive one. our grandfathers spent all their time in garages trying to fix these jalopies. many parts were strong because they were simple, and the engineers did not even try to make the design lighter.
Soviet cars were just reliable and durable. But, low performances, high fuel consumption, although they could use low grade fuel, but were having high emissions. In fact, all comunist cars were having high emissions.
I am sorry but this does not test the strength of a Piston rod. All you test is the strength of a bolt material. You should try to compress them rather than stretch. The force from the engine act compressing the rod rather than stretching.
Which is why only one them had a bolt failure, Btw if rods are only made to be compressed how about exhaust stroke ? The piston is subject to some big a$$ stretch during that phase Tell me you did not watched the vid without telling me you did watched the vid
Well I hope you live in the US because I can tell you they drink more than an alcoholic on a saturdaynight. Beautiful car, beautiful to drive but I got fed up spending over 300 euros a week just on gas.
То есть, инженеры других моделей старались, подбирали сплавы полегче, делали деталь более утонченной и при этом не сильно уступающей по прочности москвичевскому огромному тяжеленному шатуну, но слава все-таки советскому автопрому?)
Yes this is wrong process , wrong tensile test not through the rods , through the bolt crimpe and tip hole , this is as result bolt tensile testing !!!!!!!!!!!!!
Interesting that it was the bolts that broke and the old one was strongest, Would be interesting to see some high performance ones like what they use for top fuel drag racing or something. 1968 must have been a good year :).
10 месяцев назад
Actually nobody cared about how much material they use in the communist Soviet Union for a bar. He shows a Moskvich - I never dreamed about.
It just shows the lack of optimization in the Soviet design. The bolts don't need to withstand extreme theoretical forces. The connecting rod should be stressed in compression. For this tensile test, the Soviet design of just a big bolt works well, but is useless in a car that makes a fraction of the power per liter that the BMWs produce.
Love it when a classic car shows better engineering than modern design. Just think if combined what you would get for results. Great job again as always.
Interesting test , i saw conrods as young bloke in a workshop come out of a ford v8 that had been hydro locked on a few cylinders , the owner thought it would be a good idea to drill some holes in the top of his air cleaner lid below the shaker in his bonnet , it rained over night and filled some cylinders with water , and the next day he fired it up and made some of his con rods come out in an S shape , truly incredible to see .
I agree with comments about compression. Something else I'd like to mention is the weight. You could make a steel connecting rod with a huge cross-section that would win this (and a compression) test. But how does it affect the engine performance?
@@Thewatcherinthering336Another mental giant...Conrods DO fail because of compression! Ever heard of water lock? Although it's ment fail because of water lock.
This test is good. Because now you know if you find a broken conrod in your oil sump that it withstood a pressure of 5 000 KG to 15 000 KG, and the dent in the head must be equal to the opposite reaction.
Exactly what happens in an engine at high revs during valve overlap. On active compression the forces are smaller, unless there's non compressable fluid in the combustion chamber. During the combustion , the rod gets loaded up, like a coil spring, and that energy will also be released during valve overlap, contributing to the mechanical forces, already at play.
Props to you always finding interesting objects to test for us to see. Thank you my friend. Love it how you collect different rods from different cars from different era. Cheers
Moskvitch were removed from sale in UK (1970’s) due to their inability to stop… the strength of their con rods was never questioned although I’m sure Putin is making much of this Russian technological supremacy over the west as we speak.
because this was mostly testing the strength of the bolt. and Soviet one was bolt and nut going through the rod, where as other ones are bolt screwed into the rod.
It is, but the problem with overbuilding is an exponential loss of efficiency. Plus you probably couldn't rev it much past 3500 rpm for all the rotating mass.
but rather pointless... In an engine the gas explosion drives the piston downward, so the force is compressing the rod, not stretching it. On the return the force comes from the other side pushing the piston up, again compressing the rod. The bolts have very little stress (comparatively) on them in the environment they are actually used.
@@froodtube for the civilian stock engine you are correct. For the higher revving performance engine, stretchering is very much an issue. That pushing up very rapidly becomes pulling down - remember in a 4 stroke there is a compression free cycle as the bore is filled. Now stretching to the point of failure is pretty rare BUT stretching even a few mils can result in valve contact with the piston and a cascade failure shortly thereafter. And in performance applications, bigger valves for air flow and smaller combustion chambers for added compression are usually constrained by that vale to piston face clearance issue. Number one culprit for those failure is the rod bolts and there is a whole industry of aftermarket rod bolts for that very reason. Indeed, even the stretching of a tiny amount for the rod bolts can result in bearing and oiling issues which if not addressed promptly will scuttle an engine.
I found this interesting, but just saw this as a strength test for the bolts, not the actual conrods themselves. Hopefully youll be doing a crush test on them 👍
You should do this test with a set of Maxspeedingrods H beam conrods against their stock counterparts. It would be really interesting to see if they are any good. Maybe you can also devise a compression strength test.
This is not a test of connecting rods but connecting rod bolts. It remains only to hope that the author used new screws and tightened them properly - according to the documentation, otherwise this test does not make sense.
Also remember the M5 V10 has 10 cylinders and is tuned sometimes to super high horsepower, it was essentially roughly based off a detuned BMW V10 F1 engine of the era, also the M3 engines are tuned too, although this was more of a bolt strength test lol 😂
Only 2 broke at the wrist pin end, this might have a variable on floating vs. pressed pin applications, where the rod end is heated the wrist pin is placed in liquid nitrogen or in a cooler with dry ice, and pushed through the piston and rod with an arbor press until it contacts the retaining ring, this spreads the contact surface further. Floating pins require lube to achieve this effect. I also noticed the big end fasteners gave up on the rods who’s small ends held fast. Were the torque specs and bolt stretch percentages within limits? I know that it’s very critical when building extreme condition high rpm high output rotating assemblies.
To add my bit to the mix. In the 70's I owned a Ford transit and fitted a worked over 250 2V Ford I6. With exhaust opened it would rev to 7600 before valve float. Now onto the guts of my outline. We had a very severe rain storm. Unknowlingly, rain water ingressed into the intake ( 650 Holley double pumper. ) Car wouldn't start on SM. I decided to let it roll down the hill and kick start it. Fine in theory BUT dropping the clutch in 2nd gear in a 3660 lb tranny van. An almighty bang and the engine kicked over and started on 5 -1/2 cylinders. Pulled it down and found the bore had split from the hydraulic malady. Both the Ford factory piston and rod were still intact. Rod was checked and straight. Same with the factory piston. A testimony to the strength of the early Falcon I6s. Sleeved the broken bore refitted the recip assy and ran it for a another couple of years giving the 200HP hitrous kit a constant workout. LOVE DEM FORD I6s and now the Barras.
Don’t care what all the engineers have to say, this only reminds me of my Lada Niva’s toughness ! Too many salty winter Canadian roads (1982-97) but even after rust took the plates it did a few more years hauling at the cottage. Dirt cheap bare bones tanks, from Russia with love.
Awesome. You put together a great test proving failure points. Can you comment on what engine the M5’s had, V10? If it was the V10 S85 engine I’m surprized that the powdered rod held together. I expected them to fail at the small end. Maybe the OEM’s figured out how to make great powdered metal rods. It would be awesome to test the rods with new ARP and competitor bolts. Thanks
The s85 has forged powdered metal rods vs just a regular powdered metal rod like the 530's m60 rod. You can tell by the parting lines along the rod if it's forged
Interesting tensile strength test/comparison. Compression strength of the rods is just as or more important, because of the power and compression strokes putting more downward, compression, stress on the connecting rods, and wrist and crank pins.
@@Thewatcherinthering336 The rod is what transfers the downward force of the piston to the crankshaft, on the power stroke, which is compression stress on the length of the rod. It also takes the compressive stress of the compression and exhaust strokes. The rods can get bent and broken from that stress, if not robust enough. The rod does take some tensile stress on the intake stroke, but not as much as the compressive stress on the power stroke. I don't follow your, "Uhh nope." statement, or appreciate it.
@@wmden1 uhh, nope once again. You obviously have no experience with engines so just admit it. Sure the downward compression is a stress producing force on the rod, it has to be. The biggest impact from compression is on the bearing load. Tension is what breaks rods and rod bolts(think about how rods fail, they don’t get crushed, they stretch and break). This force is centrifugal force on the rotating assembly. Compression down force moves the rotating assembly without any sort of appreciable play, it’s the upswing of the piston and rod assembly that has NO stop against centrifugal force, except for the stretch of the rod and rod bolts. Even dragster engine rods get measured for stretch not compression on every tear down. Plus I don’t care if you didn’t like my comment, get a clue, build some engines first.
@@Thewatcherinthering336 I have had plenty of experience with engines, if you think there is no compressive force on the connecting rod, piston end to crankshaft end, during the power stroke, you are the one who needs to think again. Sure there is centrifugal force on the lower end of the connecting rod, and tensile to boot. I'm not saying there isn't. You are saying no compressive on the rod and that is completely incorrect. I have seen plenty of bent and broken rods. I'm done with you.
@@wmden1 once again…uhhh nope! Never once said there is no compressive force on a con rod. You said that. Obviously you have not had any experience with engines nor did you comprehend my comments. There is no compressive force on intake stroke, little compressive force on exhaust stroke, compression and power stroke have the most force. But still not nearly enough to cause catastrophic failure of a rod. Again, rods do not fail due to crushing force, they fail because they were literally torn apart from the sudden direction change at the end of the stroke combined with the centrifugal forces. Ending in an over stretched rod or rod bolt. That, clown, is what causes rods to break. No one has ever seen a crushed connecting rod except in the aftermath of a tension break. Go build some engines, take a physics course and stop being the pivot man…
After doing some math, it became obvious that the forces on a connecting rod are greatest in tension despite the logical notion than the compression forces are the higher forces. The rapid change in direction during the overlap stroke is where the greatest forces exist. In fact, compression and power actually reduce tension stress on the connecting rod. I replicated this test many years ago with the same results- the bolt is the weak point! However, as the tension increases the shape of the circle distorts and the bearing shell clearance is reduced to zero at the cap seam. Without lubrication, the bearing slips, covers the oil passage and instantly fails. Sometimes the near instant increase in friction at high RPM results in the next weak point, the small end to break the rod at the point just below the small end bearing. Key thing here is use high quality rod bolts, torqued precisely, quality oil, and know the RPM limit because that is the failure point, not the combustion forces. Rev your engine till it spins a bearing, rebuild it and lower the red line by 500? Rev limiter?
The highest loads on connecting rods are in compression rather than in tension as it's the expanding, hot gasses pressing down which provide the greatest forces. There are, of course, significant tensile forces too, as on the induction stroke, the piston has to be accelerated downwards quickly (on the firing stroke the hot gasses push the piston down). Not to say that tensile strength isn't important, but they are optimised for the compressive forces and will be stronger in that direction. You can often see the difference on an older, stripped down engine with different wear patterns on the big end bearings.
💪🔩💥 Interesting clash of forces! Connecting rods and tensile load don't seem to be the best companions. 🤔 It's intriguing how they hold up under compression in engines, yet fail under different conditions. I wonder if there's a way to enhance their tensile strength for better performance. 🏎 Let's dive deeper into the world of connecting rods and their design limitations. 💡
In automotive racing engines, the metallurgy with the connecting rods have improved immensely from the 1950s to the present; especially so in the US NASCAR race series; where the engines used, as its base, were the high performance engines from the US automotive manufacturers [General Motors, Ford, & Chrysler]. The term "blown engine" was used to describe engine failures among the participants in the NASCAR races in the 1950s through the '70s; and was especially common in the 1950s and '60s. Many times those "blown engines" were due to connecting rod failures. But in the 21st century, the rate of blown engines, in NASCAR races, are seldom, and I can't recall the last time there was an engine failure due to a broken connecting rod in the past 20+ years of NASCAR races.
Seen quite a number of conrod failures. All have been due to tension, not compression. Applies to both plain bearing conrods with bolts and roller bearing boltless ones. So I think this tests are valid. Last one I've seen this winter had big end and small end intact and conrod in three pieces. Fractures was definitely due to tension. I thought this is common knowledge as it was known in the 1940ies possibly earlier.
High RPM requires stronger rods, too. Usually, a bearing will go long before a rod. Turning a normally aspirated car by turbo conversion will have parts fail in the bottom end. Use forged pistons and rods and uprated bearings. Bit off topic there but im a petrol hesd.
Interesting concept of how to try to demonstrate the effects of tension stress in action! Would be awesome if someone could somehow demonstrate the strength of the rods themselves rather than the bolts. Perhaps by welding the bottom end to a extra strong steel bar? Either way, thanks for your efforts to demonstrate a theoretical problem in a practical way regardless of the practical value of the demonstration as such.
Superb demonstration of Raw Strength. No doubt people will moan about Physics etc, but the Traban was stronger ! Easier to understand when Profit was not in the equation so much back then.
There are other actions going on inside the engine. My father owned a garage for over 60 years and I've seen a lot of broken connecting rods, although I've never seen the rod bolts break and I don't recall ever seeing one break at the wrist pin end. They usually break in the beam, sometimes in the middle, sometimes near the big end. I've also seen some that were just bent and not broken.
LOL for that old russian moskvich just destroying them all🤣🤣 also would be fun to test rods from lada niva, many times i have seen one suck in water when offroading, and that usually bends or breaks a rod, but those just don´t tend to break that easily...
@@TheInsultInvestor If you are going to be like that, then you forgot to capitalize that Y and end the quotation with a period. Also, to correct someone, you use a "*".
Comments regarding compressive strength being what matters- do you guys work on things? Do you find connecting rods crushed from compressive forces? I think maybe "no" on both counts. I have seen bolts break in tension, and rods snapped due to cantilevered forces, after oil starvation and seizing to a still a spinning crankshaft. I have seen rods bent due to compressive forces from hydraulic locking...water ingestion. One of those ran tens of thousands of miles very bent, and was found when disassembled for unrelated reasons. Never saw a rod fail in compression. Maybe top fuel guys do? Even rods from engines I knew were suffering from preignition showed no distress, and this is pretty abusive. Probably more so to the bearings. I think you may be imagining some impossibly large explosion occurring...not so. While forceful, it should be a somewhat smooth event. BMEP, or average cylinder pressure during the power stroke, isn't that awful high. Over 200 PSI BMEP is pretty good. Also, the bolts are irrelevant when the rod is in compression, but certainly matter @ TDC. "You're just testing the bolts.." is a strange comment. They are part of the rod, and are a failure point. I read in these comments, and elsewhere, that the rod's toughest moment is the piston deceleration between the exhaust and intake stroke. Similar forces probably exist at BDC...but, again, I see rods/bolts fail in tension, not compression. A last observation- this guy is breaking stuff in his press for our amusement, it's not an engineering class. Just enjoy it. I Crush stuff in my 75 ton press for fun sometimes, my kid loves it. Me, too.
lol what kind of joke are u, OF COURSE rods are bend or crushed from compressive forces esp when u add way more tq to an engine for example by a bigger turbo. it happens every day. so just stfu if u are that clueless
Well, connection rod would never suffer such forces, unless piston will stuck in chamber, but that wouldnt create such a strong force. This test was supposed to be about connection rods, not their bolts. As from engineering middle school, almost every student of physics know how this test might be done. We know from the top of our heads also the diagrams for steel of this tests. More importantly, it might be very interesting to see the results of usual rod a M3 for example, because they might be forged by better technological process, BUT IN PRESS. This test is useless. Thats how it is, not everyone is stupid.
These Conrods are designed with different forces in mind, a camshaft seems brittle if you smash it on the ground but can do thousands of miles in an engine.
Sorry, but you not testing strenght of conrods, but strenght of screws. Conrods in engine must withstand the pressure, not tension. In the correct direction of stress, the screws are not stressed and the part can withstand much more force. Great video, out of reality.
No. Compression force is only one thing. There are other important factors like tensile force (very high during starts/stops), bending force (stress while in motion) and shearing force (stress experienced by the bolts).
@@ejsampana426 in this pulling force the main things suffering until break are the bolts, the con rods are also but in less scsle and is not the right kind of effort this piece experience through its life in the engine, that's the main echoe for me at least.
Decent test. Most rods fail on the exhaust stroke as they try to stop the piston and make it change direction - in a sound motor. In a wore out engine, it may be for any reason like spun main locking up the bottom end, etc ...
Interesting. But resistance is often done by the screws . It would be great to test the Shape in compression , that is the main effort that a conrod is made for.
For this test, you need to ask yourself a good question: what does the connecting rod pull test show? In practice, the connecting rods in engines are subject to pressure during operation, tensile forces are marginal. The tensile test measures the strength of the material, but the smallest area of the material that can be stretched must be taken into account. Such a test includes, for example, kg/mm² area. In addition, there are also bolts that connect the connecting rod parts. So what should be measured in the end? - the strength of the bolts or the connecting rod itself? The tensile test shown for the connecting rods makes no sense in practice and can only be presented as a curiosity.
Cool test but most only broke at the bolts/threads. Revisiting this with some ARP hardware would be interesting. For those mentioning compression, it's rare a rod will bend/break due to compression unless the motor ingests water or someone is running a lot of boost at low rpm or the motor is detonating.
surely it's also rare that a rod will fail under tension? the only tensile force on them is their own weight under however many G they decelerate/accelerate at in the top half of the exhaust/induction stroke. the compressive forces are always higher.
@@JTV84 usually a thrown rod starts with a spun bearing. If the oil and bearings are good the next likely thing is high rpm. Rod length, stroke length, piston weight all play a role in max safe rpm.
