Re: Aluminum rods on street??
[Re: vttm]
#1128277
12/05/11 06:58 PM
12/05/11 06:58 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Drive it, melt tires , have fun No worry!! If it was built right, it will be Fine!
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Re: Aluminum rods on street??
[Re: joshking440]
#1128281
12/05/11 09:04 PM
12/05/11 09:04 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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Yea you just don't beat on them till there up to temp.
Brett Miller W9 cnc'd heads STR Chassis fabraction
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Re: Aluminum rods on street??
[Re: vttm]
#1128282
12/05/11 09:04 PM
12/05/11 09:04 PM
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Joined: Jul 2008
Posts: 30,474 Florida STAYcation
dOc !
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,474
Florida STAYcation
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Quote:
would it be possible to run aluminum rods for short distances on the street say 10 miles or so? School me on who's correct and why.
10 miles is a STREET CAR ? ..
HOPPING ON 95 and driving to FL from MD is a STREET CAR ...IMHO !
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Re: Aluminum rods on street??
[Re: jim sciortino]
#1128285
12/06/11 03:06 AM
12/06/11 03:06 AM
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Joined: May 2011
Posts: 625 Oakville, Wa
HOTMOPR
mopar
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mopar
Joined: May 2011
Posts: 625
Oakville, Wa
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BME says their rods are fine for the street. Its all about using good oils. http://www.bmeltd.com/rods.htm
67 Barracuda, 470" B, Glide, FuelTech FT600, Precision, Ptc, QA1, Calvert, Smith racecraft, Afco, Dana 60. 275 radials
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Re: Aluminum rods on street??
[Re: HOTMOPR]
#1128286
12/06/11 03:34 AM
12/06/11 03:34 AM
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Joined: Jan 2003
Posts: 19,382 Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,382
Las Vegas
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Done it many times with zero issues. In fact we use to use or old race rods in street engines all the time.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Aluminum rods on street??
[Re: vttm]
#1128287
12/06/11 12:38 PM
12/06/11 12:38 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,210
New York
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Ah yes. The Forum, where everyone's opinion has equal value.
Boffin Emeritus
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Re: Aluminum rods on street??
[Re: dogdays]
#1128289
12/06/11 02:34 PM
12/06/11 02:34 PM
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Joined: Mar 2008
Posts: 292 NY
challenger451ci
enthusiast
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enthusiast
Joined: Mar 2008
Posts: 292
NY
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Quote:
It has nothing to do with temperature.
It is all about fatigue life. Let's take steel for an example. As steel goes through millions of tension/compression cycles its strength goes down. At some point the strength levels out, IIRC at about 57% of new. Then the curve of strength vs. cycles is flat. Now let's look at aluminum. As the cycles mount up the strength goes down...and down...and down. The curve never levels off. It continues until it hits zero. By that time your aluminum part has long since broken. Sounds bad, doesn't it? But there is a question. How come some aluminum parts last longer than we would expect? I think it has to do with the amount of cyclic stress to which the aluminum part is subjected. Maybe the curve becomes less steep if the part is only stressed to, say, 50% of yield or ultimate. Then the acceptable service life would be extended past the time that an overhaul was needed.
Does anyone have any references for this?
R.
IIRC, in order for the part to fatigue, it has to be loaded (stressed) above the fatigue strength. If the rods are designed so that at a given bobweight and RPM limit, no section is loaded beyond the fatigue strength rating, they'll theoretically last forever in that application. Big question is, how sure can you be that you're under the fatigue strength???
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Re: Aluminum rods on street??
[Re: dogdays]
#1128291
12/06/11 09:50 PM
12/06/11 09:50 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,210
New York
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All Triumph and BSA 750 3 cylinders had aluminum rods. 7,000 RPM engine. 70,000 miles reported frequently.
Boffin Emeritus
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Re: Aluminum rods on street??
[Re: dogdays]
#1128292
12/07/11 02:56 PM
12/07/11 02:56 PM
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Joined: Mar 2008
Posts: 292 NY
challenger451ci
enthusiast
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enthusiast
Joined: Mar 2008
Posts: 292
NY
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Quote:
No. As the aluminum part fatigues the strength keeps going down as the number of cycles goes up. It eventually goes to zero.
What you are describing is for steel, where it levels out at some point.
That's why people don't worry so much about steel connecting rods.
But I'm not sure if a cycle at say 10% of the new tensile stress is the same as a cycle at 90% of the new tensile stress. I am looking for that answer. A lot of this metallurgical stuff isn't "logical" unless you're a metallurgist.
Briggs&Stratton engines use aluminum connecting rods.
Suppose your part will break at 10 million cycles. How many miles is that?Let's use a 27" tire and 3.91 gears. Assume all of the mileage is in High gear. So you have 2,921 revolutions per mile at the crankshaft. How does 3,423.9 miles sound?
I'm back to liking steel rods more and more.
R.
If you NEVER load the part past the fatigue strength it will NEVER fatigue. I understand that this number is not a constant once the material BEGINS to fatigue. The point I'm making is the material won't ever fatigue if it is not loaded past the fatigue strength. An aluminum part will have a fatigue cycle limit at a given load. If you're below that, fatigue doesn't enter into the equation. BTW, the tensile stress in a given part at a given load is the same regardless of fatigue strength of the material.
I think this is why a properly applied (overkill) aluminum rod will last virtually forever. If the rods are not properly applied, they will have a life cycle. Since this is not easy to measure in an engine, most engine builders change rods after X-number of cycles as an insurance policy just in case the rods are stressed to beyond the fatigue strength.
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Re: Aluminum rods on street??
[Re: dogdays]
#1128295
12/07/11 08:49 PM
12/07/11 08:49 PM
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Anonymous
Unregistered
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Anonymous
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UUmmmm... like we were saying----Run them, have fun, melt tires. Too much science , not enough rubber burning here. And that opinion is based on experience.
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