Billet Rods

Diesel Tech said:
While the others have already answer most of why this post is incorrect one of the major things that is not covered is the load placed into the piston then pin then rod then crankshaft. The weight of the piston and pin needs to be handled when the rod reverses direction. The worst time is not in compression of this but when it's on the exhaust stroke to intake stroke. The weight of the piston assemble want to keep going right out the top of the block. Then you need to handle the transfer of the load during the compression stroke from the piston pin to the rod and onto the crankshaft. You can do it many ways but you must look at the whole picture just not one part of it.
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Agreed 100% and I feel remiss for not bringing it up. There's a few papers out there that show how to calc all the forces. What the paper said is, the nature of the load depends on cylinder pressure (compressive) and the inertia load at RPM (tensile). From my foggy memory, the tensile load goes up with the square of the RPM. It's also why rods see the very definition of a fatigue load - fully reversing stresses.

OK, here's a stupid question though. In a Dmax, the stock rods almost always fail by bending. I think the same goes for stock Cummins rods but not sure. Does this indicate that for this particular case that the compressive loads are always higher than the tensile loads? Or again is it very RPM sensitive?

You would think that if the tensile loads were consistently higher, the rods would stretch, rather than compress.

??? Dunno what to think.
 
Sledpuller said:
Not full load? Its 40,000 pounds, thats goes from rolling /slight drag resistance, to full on dragging resistance.
If anything its 100% load, to 200% load.

You racers would blow your shorts if you had to tow a 10,000 camper trailer down the 1/4 mile.
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Yes, we would blow our shorts but if you woke up that would also blow our shorts. One of the key factors you keep skipping is the traction issue, once you lose traction the load stops. The other is the 40,00 pounds your so proud of is BS! The sled rolls on tires with wheel bearings until the weight box moves forward and start pushing the pan down and most of the time is is not event full of weight so its something less. Sled pulling is a dirt track and drag racing is a pavement surface with a glue applied to it. You can put a million pounds on the sled but the point at which traction is lost your done. It does not matter if its 5000 lbs or a million pounds once traction is lost its over! This is going to occur over a 300- 400 foot track at best! I've been to many sled pulls and most are less than 10 seconds once the truck leaves the line. Drag racing on the other hand allows for more power to be applied much quicker and harder for longer periods of time. Then turn around and do it over and over again at the same race. Most high powered sled pullers need at least 2-3 hours between runs and that would buy you a DQ drag racing.

Both are hard on parts but to say one is harder on rods than the other is total BS and Gene is full of that!
 
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nwpadmax said:
Agreed 100% and I feel remiss for not bringing it up. There's a few papers out there that show how to calc all the forces. What the paper said is, the nature of the load depends on cylinder pressure (compressive) and the inertia load at RPM (tensile). From my foggy memory, the tensile load goes up with the square of the RPM. It's also why rods see the very definition of a fatigue load - fully reversing stresses.

OK, here's a stupid question though. In a Dmax, the stock rods almost always fail by bending. I think the same goes for stock Cummins rods but not sure. Does this indicate that for this particular case that the compressive loads are always higher than the tensile loads? Or again is it very RPM sensitive?

You would think that if the tensile loads were consistently higher, the rods would stretch, rather than compress.

??? Dunno what to think.
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I've got a few sets of Cummins rods here that are twisted and also have the thrust surfaces destroyed while the beam is still in good shape. That alone shows the side loading is happening in this application. I've also seen Cummins rods that the pins have ripped out of the top which again shows the reversing problem. The problem with the ones with the pin hole ripped out is that rod beat the hell out of everything else so there was no real useful data that we could get from them.
 
Diesel Tech said:
I've got a few sets of Cummins rods here that are twisted and also have the thrust surfaces destroyed while the beam is still in good shape. That alone shows the side loading is happening in this application. I've also seen Cummins rods that the pins have ripped out of the top which again shows the reversing problem. The problem with the ones with the pin hole ripped out is that rod beat the hell out of everything else so there was no real useful data that we could get from them.
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Oh please.....

It isn't even a question, this is what our rods are doing.......
DSC00168.jpg


"OK, here's a stupid question though. In a Dmax, the stock rods almost always fail by bending. I think the same goes for stock Cummins rods but not sure. Does this indicate that for this particular case that the compressive loads are always higher than the tensile loads? Or again is it very RPM" sensitive?

Ding Ding Ding.....
Compressive!!!

I've only seen a couple of rods that a Scheid truck threw at like 7K and the pin pulled out the end....the rod didn't break....the one place a H beam would have a advantage.....but what good is that, when the pin's pulling out the small end anyways?
 
Diesel Tech said:
One of the key factors you keep skipping is the traction issue,
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And gearing!!!!

What is harder on an engine............3.73 rear with a 0.84 final drive ratio........or having a transfer case in 4x4LO??

Hell Gene, you could pull a sled with a 3hp Briggs&Stratton with enough gearing!!:doh::hehe:
 
Dockboy said:
And gearing!!!!

What is harder on an engine............3.73 rear with a 0.84 final drive ratio........or having a transfer case in 4x4LO??

Hell Gene, you could pull a sled with a 3hp Briggs&Stratton with enough gearing!!:doh::hehe:
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How about the Scheid rail?? Thats comparible power to their pullers, and traction is a BIG issue.....

Sure it looks like on the pullers the tires are spinning like crazy.....so what? There still putting 1500-2000 hp to the ground.

:poke:
 
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Joesixpack said:
I've only seen a couple of rods that a Scheid truck threw at like 7K and the pin pulled out the end....the rod didn't break....the one place a H beam would have a advantage.....but what good is that, when the pin's pulling out the small end anyways?
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I guess my point is, based on the geometry and weights, I'm proposing that there is a crossover RPM where one load exceeds the other.

Maybe the CR trucks with somewhat limited RPM see only the failure from bending in compression, whereas the big RPM engines may fail more from tension.

Tuning could also be a big part of it. An engine with high timing and high cylinder pressure spikes may show damage from compressive stress before the tensile becomes evident.

It could be very individual to each engine based on operating setup. I don't think there's a hard and fast rule you can apply like a recipe.
 
Joesixpack

Never said they do not bend but what I did say is that I have twisted ones as well as ones with the thrust surfaces wore out too. So you need to look at it all! The pin is not the only advantage to an H design in this application. Will an I design work, sure, but to say that it is stronger is pure BS! As far as Scheid's rail I've watched it many times hook just fine and other times spin the tire. Bo, Jeroid and Dan are friends of mine and I been right there on the line with them. The argument is the same, and that is once you loose traction the load goes away. That point is much lower on a dirt track than on a properly prepared pavement surface with glue applied. Let's take your example and put the rail on the dirt track and see how well it does with drag race tires on it..................... seems pretty dumb to do that now doesn't it. Those tire would not work just like dirt tires do not work drag racing. Then look at the total effective gear ratio and see how much of the load really gets back to the motor.

Were talking about loads the engine see that the rods need to hold. From what I have here and what I have seen the Cummins has a few issue that needed to be solved. We did it with an H beam design as we felt that worked the best in this case. So far that design has been working fine with no failures in high Hp Cummins motors.
 
I have seen the pin pulled out of the piston but it was because the piston got hung up not that it was trying to preventing the piston from going into space.

BBD
 
Diesel Tech said:
Yes, we would blow our shorts but if you woke up that would also blow our shorts. One of the key factors you keep skipping is the traction issue, once you lose traction the load stops. The other is the 40,00 pounds your so proud of is BS! The sled rolls on tires with wheel bearings until the weight box moves forward and start pushing the pan down and most of the time is is not event full of weight so its something less. Sled pulling is a dirt track and drag racing is a pavement surface with a glue applied to it. You can put a million pounds on the sled but the point at which traction is lost your done. It does not matter if its 5000 lbs or a million pounds once traction is lost its over! This is going to occur over a 300- 400 foot track at best! I've been to many sled pulls and most are less than 10 seconds once the truck leaves the line. Drag racing on the other hand allows for more power to be applied much quicker and harder for longer periods of time. Then turn around and do it over and over again at the same race. Most high powered sled pullers need at least 2-3 hours between runs and that would buy you a DQ drag racing.

Both are hard on parts but to say one is harder on rods than the other is total BS and Gene is full of that!
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Steve if there was no load there, then how are the mod guys keeping the twin chargers lit that they are? RPM alone isn't doing it, how many drag trucks are running the chargers the mod pullers are?
 
It's not that there is no load, but once you loose traction the load goes down. So it's all about traction, gear ratio and RPM and a drag race motor see's more of it than a sled puller motor. A typical sled puller runs what final gear ratio? A drag race truck runs many passes at speeds approaching 145 MPH at 5000 RPM with a 34" tall tire. Anyone want to figure the areo drag on a truck traveling 145 MPH versus a truck pulling a sled at 35 MPH? A sled puller runs a ground speed of 35 MPH at 5000 RPM with a tire at least 34". So now you tell me who has more gear reduction! Gear reduction lowers the torque load on the motor itself, that's just the way it works.

What's funny is this is supposed to be about rods and it's been pointed out by many that our rods are working fine in High HP drag race engines so now the sled puller wants to say its different in a sled pull motor. AS I said before get past the advertising hype and back to the real world and you will find there is not much if anything different between the two.
 
I'm not selling rods..........

Ok sled pullers, the mighty Diesel Tard has spoken, since you spin your tires on dirt,there is NO LOAD on your truck.
All those stacks of Dana 80s, Rockwells, reversers, drop boxes, broken frames/hitches, etc just failed on their own.

The sheer idiocy of your blow hard explanations about what you think is real on the pulling track astound even me.

Oh and someone tell D.O.T that we can haul a million pounds if we so choose, as long as its rolling on wheel bearings, because then it doesn't weigh as much.:what:

Some one help , me is Steve Cole for REAL???????????:redx::redx::redx:
 
nwpadmax said:
Agreed 100% and I feel remiss for not bringing it up. There's a few papers out there that show how to calc all the forces. What the paper said is, the nature of the load depends on cylinder pressure (compressive) and the inertia load at RPM (tensile). From my foggy memory, the tensile load goes up with the square of the RPM. It's also why rods see the very definition of a fatigue load - fully reversing stresses.

OK, here's a stupid question though. In a Dmax, the stock rods almost always fail by bending. I think the same goes for stock Cummins rods but not sure. Does this indicate that for this particular case that the compressive loads are always higher than the tensile loads? Or again is it very RPM sensitive?

You would think that if the tensile loads were consistently higher, the rods would stretch, rather than compress.

??? Dunno what to think.
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The buckling load CAN (not always) be larger than the tensile yield load. Typically a material's compressive properties are better than that of tensile. I believe that the most common used formula for calculating buckling load is:


Buckling Load=(pi^2*modulus of elasticity*Moment of Inertia)/((Length*Length factor)^2)

Where the length factor of a pin-pin joint is 1.

There are also other formulas, but this is the most used, and quite frankly the easiest to work out.
 
We all know the only thing you sell is your bucket of BS. When is it that you are really going to quit talking all your BS and come do something?
 
IMHO drag racing is worse... i sure as hell break more tranny parts on the track.

nwpadmax said:
I dunno. If you were running cut Cepek puller tires and had ungodly traction then I would say it's possible to be loaded harder. But with most DOT tires there's enough slip on the dirt that it might not be loaded as hard as you might think.

The drag guys with 4 grippy tires experience a hell of a lot of driveline damage. The upshifts can be nasty. Maybe the instantaneous loads are much higher on asphalt, whereas on the dirt you have a higher average load (but not as peaky). And it would depend also on how fast of a time slip. A 14 second run is probably nothing compared to the guys in the 10s or faster.

Dunno. Both are highly loaded, in different ways.
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IMHO Diesel Tech has spent a lot of energy and time explaining what I always felt was pretty obvious. We have local guys out my direction that won't run at the track because they break parts when they do. But they are very mighty pullers. lol
 
I'd bet a bag of marbles the best billet factory tranny would absolutly explode planted it behind Scott's engine in BBD or Cory's cat puller.

Well I'd give Opie's a chance......
 
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