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Re: Oliver I-beams or Manley Pro I-beams?
[Re: WadeMetzinger]
#1741352
01/29/15 01:54 PM
01/29/15 01:54 PM
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Joined: Jul 2010
Posts: 1,845
Tampa
DusterDave
top fuel
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top fuel
Joined: Jul 2010
Posts: 1,845
Tampa
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Quote:
Quote:
Why not a aluminum rod? Help with the shock load of the nitrous not transferring to the crank or mains.
Carrillo are a lot better then these choices.
Aluminum rods on street motor is not a good idea, I've spoken to most of the aluminum rod manufactures and they don't recommend and tell me to go steel.
I guess you didn't speak with BME. Their President says (copied from BME's website):
"In a hot street application, using the aluminum rod is a no brainer," BME President, Bill Miller, said in an interview with an automotive magazine. "I don't know how the myth that aluminum rods can't be used on the street got started, but I'll guess that, back in the 60s and early-70s, they weren't making them using the process we're using today. With the material we've got and they way we manufacture the connecting rods, they'll live a couple hundred thousand miles on the street because a street application is, for the most part, low load. Our basic Aluminum Rod is made for an 1000-hp, 10,000 rpm race engine. The design criteria for the connecting rod is way overkill for what it's going see on the street. We been running aluminum rods on the street for more than two decades."
Gone to the dark side with an LS3 powered '57 Chevy 210
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: brownout]
#1741355
01/29/15 02:21 PM
01/29/15 02:21 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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With the aluminum rod, one solves the tensile strength problem with more cross-sectional area. That isn't hard to do, been done for ages.
The problem is fatigue resistance. Aluminum has none. That means that as the stress cycle number builds up, the actual strength of the aluminum goes down, and it continues all the way to the point where the rod strength equals the stress placed on the rod, then it fails.
There is another issue that has never been definitively answered, though. Does a stress cycle, at less than maximum, count in the total cycle count? I have done numerous literature searches and never found a definitive answer. Maybe someone on the board knows more about it than this, if so speak up.
R.
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: dogdays]
#1741356
01/29/15 02:29 PM
01/29/15 02:29 PM
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Joined: Oct 2007
Posts: 3,978
Hilltown Pa
1967dartgt
master
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master
Joined: Oct 2007
Posts: 3,978
Hilltown Pa
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Quote:
With the aluminum rod, one solves the tensile strength problem with more cross-sectional area. That isn't hard to do, been done for ages.
The problem is fatigue resistance. Aluminum has none. That means that as the stress cycle number builds up, the actual strength of the aluminum goes down, and it continues all the way to the point where the rod strength equals the stress placed on the rod, then it fails.
There is another issue that has never been definitively answered, though. Does a stress cycle, at less than maximum, count in the total cycle count? I have done numerous literature searches and never found a definitive answer. Maybe someone on the board knows more about it than this, if so speak up.
R.
So do steel rods have a life? Would they want to be changed out in a 1200 hp engine?
Brett Miller W9 cnc'd heads
STR Chassis fabraction
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: dogdays]
#1741357
01/29/15 02:34 PM
01/29/15 02:34 PM
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Joined: Feb 2014
Posts: 655
Huntsville, AL
Airwoofer
mopar
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mopar
Joined: Feb 2014
Posts: 655
Huntsville, AL
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Quote:
With the aluminum rod, one solves the tensile strength problem with more cross-sectional area. That isn't hard to do, been done for ages.
The problem is fatigue resistance. Aluminum has none. That means that as the stress cycle number builds up, the actual strength of the aluminum goes down, and it continues all the way to the point where the rod strength equals the stress placed on the rod, then it fails.
There is another issue that has never been definitively answered, though. Does a stress cycle, at less than maximum, count in the total cycle count? I have done numerous literature searches and never found a definitive answer. Maybe someone on the board knows more about it than this, if so speak up.
R.
As a general rule, stress damage is cumulative. Ask the paperclip which you got away with bending once, how it feels after the 5th bend. It's also why we replace rod bolts and why jet engines have time limited parts that get replaced despite no cracks or dimensional changes.
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: Airwoofer]
#1741358
01/29/15 02:49 PM
01/29/15 02:49 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Steel has fatigue resistance. When one looks at a strength vs. cycles chart, the steel's strength decreases with the number of cycles, until at around 57% of the original tensile strength, the curve goes flat. So as long as the maximum load does not exceed that 57% value, the part does not fail. For aluminum the strength vs. cycles curve continues down until it hits zero.
That's the simplified version. There are other factors which affect the steel, such as surface condition and size effect, the first two that popped into my mind
And yes, I know that stress is cumulative, at least stress cycles are. But the question of what constitutes a cycle hasn't been defined very well, at least in my research. Saying that we replace aluminum parts after so long is like saying ice floats on water. The fact that it does gives no explanation of why it does.
R.
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: Airwoofer]
#1741359
01/29/15 02:53 PM
01/29/15 02:53 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Even steel has a fatigue life, it is just a ton longer than aluminum, so much better that it is basically a non factor. A pile o junk volvo can go a million miles and the rods are almost as strong as new. All metals have a certain number of cycles before they fail, aluminum is within the realm of posibility in a conecting rod, steel is not, now a piston has even less stress than a rod so it can be made of aluminum and basically never fail from cycles unless pushed beyond it's elastic point by severe detonation or too hot, steel pistons would probably never melt in an internal combustion engine. I would bet money however that they do have aluminum alloys with longer fatigue life now than they did in the 60s.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: 1967dartgt]
#1741361
01/29/15 03:00 PM
01/29/15 03:00 PM
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Joined: May 2003
Posts: 6,561
Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
Posts: 6,561
Downtown Roebuck Ont
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ALL rods have a finite number of laps in them regardless of material. One of the local go to roundy round builders here uses steel rods of the caliber being discussed for his dirt modified engines. He tells his customers they are done at 600 laps. Anybody that doubted him has found that they had a $25,000 doorstop before they made it to 700 laps. Is there a difference in the stress cycle count between WFO and 1/2 WFO? I would say absolutely, but I don't know how you would quantify it.  If you call BME and tell him how much your pistons weigh, how much spray and how many RPM you're going to twist it, he will give you a lap number to change them out at. He would likely have some kind of formula to calculate how much to reduce that lap count by to compensate for the street miles. Kevin
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: HotRodDave]
#1741362
01/29/15 03:16 PM
01/29/15 03:16 PM
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Joined: Feb 2006
Posts: 2,379
MD
Kevins493
top fuel
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top fuel
Joined: Feb 2006
Posts: 2,379
MD
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Basically when fatigue tests are done, they are done on a rotating fixture with a weight on it. As the test sample rotates, the loads at at any given point are cycled from compression to tension depending on where that point is in its path of rotation. The load is set at the beginning of the test and the sample is run until failure. Then another load is put on another test sample and the process is repeated until you can make a graph from the data. Thus when you look at a graph of fatigue life, you are looking at cycles to failure at a given load.
In the case of steel, this graph will level off (or nearly so) at some value for load, and this is called the fatigue strength of the material. Steel that is loaded below its fatigue strength is assumed to be able to withstand an infinite number of cycles.
Aluminum, on the other hand, never levels off. This is why it is said to have "no fatigue strength". Thus, even with very low loading it will still eventually fail, albeit after a very large number of cycles. Part of this is due to the fact that aluminum cracks as it is cycled, and with every cycle the cracks grow a little more. A good example of this is around the rivet holes on an airplane (which is where the stress concentration is highest). Any aluminum-skinned airplane flying today will this cracking to some extent,and the airlines are actually required to track the length of the cracks so that they know when to perform a repair. This is also why airliners are no longer eligable for service in the US after a certain number of pressurization cycles.
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: MattW]
#1741364
01/29/15 05:22 PM
01/29/15 05:22 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Thanks, Kevin, for restating my post in a perhaps more understandable way.
Some things are facts, not open to having a differing opinion. So to that crowd, feel free to have a differing opinion, but I will know that you are wrong.
Race car parts are usually taken out long before they would need to be, in order to eliminate DNFs. But here's the deal: A properly-designed race car part will have a very low factor of safety, meaning it is as light as they can get away with. So the factor of safety in the design is probably much smaller than the factor of safety in a 318 rod, for example. As a matter of fact, one could design a rod to fail at a given load, after so many cycles, that number being the number of cycles in a typical race plus any qualifying. This would be the lightest possible rod. That would also be a rod that got thrown away after that one race.
Now where this intersects with me is this: If I keep the rod's stresses below the stress limit, I can use this rod indefinitely. And as I don't run my engines at 9000 rpm, 6000 being a more likely number, as long as I don't go crazy with piston weight or stroke length the rods will be OK. I could figure this out and when I get closer to building an engine using some of these used NASCAAR parts, I probably will just to see what's a safe redline for my combination.
I am still looking for a definitive answer to the question about low intensity cyclic loading for aluminum.
R.
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: dogdays]
#1741365
01/30/15 02:43 AM
01/30/15 02:43 AM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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Quote:
Thanks, Kevin, for restating my post in a perhaps more understandable way.
Some things are facts, not open to having a differing opinion. So to that crowd, feel free to have a differing opinion, but I will know that you are wrong.
Race car parts are usually taken out long before they would need to be, in order to eliminate DNFs. But here's the deal: A properly-designed race car part will have a very low factor of safety, meaning it is as light as they can get away with. So the factor of safety in the design is probably much smaller than the factor of safety in a 318 rod, for example. As a matter of fact, one could design a rod to fail at a given load, after so many cycles, that number being the number of cycles in a typical race plus any qualifying. This would be the lightest possible rod. That would also be a rod that got thrown away after that one race.
Now where this intersects with me is this: If I keep the rod's stresses below the stress limit, I can use this rod indefinitely. And as I don't run my engines at 9000 rpm, 6000 being a more likely number, as long as I don't go crazy with piston weight or stroke length the rods will be OK. I could figure this out and when I get closer to building an engine using some of these used NASCAAR parts, I probably will just to see what's a safe redline for my combination.
I am still looking for a definitive answer to the question about low intensity cyclic loading for aluminum.
R.
How many run aluminum (a truely crap material for a rocker BTW) rocker arms and never blink an eye?
The biggest killer of aluminum rods is the guy who likes to fire his junk up in the trailer, whip the throttle 5-6 times, back it out and pull to the burn out box. I think a good aluminum rod can live on the street.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Oliver I-beams or Manley Pro I-beams?
[Re: madscientist]
#1741366
01/30/15 09:10 AM
01/30/15 09:10 AM
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Joined: Mar 2003
Posts: 1,629
pa
572charger
top fuel
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top fuel
Joined: Mar 2003
Posts: 1,629
pa
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olivers in mine since 2003 !!!!
606 hemi pump gas best 9.60 at 142mph on motor
05 hemi daytona 1500 go-mango 4wd quadcab
2007 hotrod mag pump gas drags runner up, roadkill nights dodge big tire winner 2018 2019 back to back
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