Interesting billet rods - USA made

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SteveBorland said:
Do you have any actual evidence of these rods failing in use?
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There's a lot of the usual marketing blabla on the R&R homepage but there's also one comment which is surprisingly honest: Even the manufacturer himself calls these rods a "maintainence item". Aluminium doesn't have a fatigue limit. It's like an inbuilt counter which "measures" cycles and loads. If it goes to zero the part will fail.


Tim
 
Agreed, the bolts in the R&R rods are 190,000 psi UTS, but the rod material is only 90,000 psi. The Carrillo rod material is 195,000 psi UTS, and their bolts are 220,000 psi UTS (H-11 tool steel). For additional cost they will provide bolts in a multiphase material at 285,000 psi UTS. We could argue about whether you need all that for a Norton, but there's no real argument about which is stronger and has more long term durability under hard use.

I think what bothers me about the R&R rods is this statement on their web site

"Unlike a forging in which the aluminum is literally pounded into the shape of a rod, our material is cold worked, forced through a die at extreme pressures, to form the billets from which the aluminum rods are CNC'ed from. This work hardening builds the strength, grain structure, elasticity, and general characteristics that makes our aluminum rods superior to common forgings. Our alloy is then further artificially aged and heat treated, then stress relieved though additional manufacturing processes."

I think that is a bit misleading. The usual benefit claimed for machining from a forging is that the grain flow is in the shape of the final product, so you're not cutting across the grain as much in machining as when starting from a billet. I'm willing to accept that R&R use a very high quality material for their billet, but that doesn't make it as good as or better than a good forging in similar material.

Let me insert a little disclaimer here. I've had great luck with stock Commando rods in both street and race bikes. In the race bikes I had them shot peened and regularly checked for cracks. I also check for cracks before I use them in a street bike engine. I've never broken a stock Commando rod, but have retired one or two with cracks around the pin end. But those were from regularly flogged race bikes. I have no hesitation to use stock rods in a street bike engine. That's what I ran in my 920 engine on nitrous last year at Bonneville, and they still look good. Still, I'm going with Carrillos for the next race build. One less thing to worry about.

Ken
 
I would feel a lot more comfortable with an R&R rod if it had a steel cap like a Norton rod. [that is if it fit without compromising the cases by reliving for clearance]

The fatigue is going to affect the cap first and that is where I have seen failures of all aluminum rods that were run very long. Jim
 
No-one seems very keen on these rods, but no-one has seen one broken yet?

A65s had all alloy rods, and I suffered a seized big-end on mine. It locked the back wheel at around 90mph (on the M61 near Chorley!), but the rod didn't let go.

R&R aren't alone in believing alloy rods have a place...

Broken link removed
 
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Gidday All

Ickren, JimC, Dances, thanks for your corrections to my explanation. .
as I have said, I am not an engineer.
All this stuff by you fellas is really helpful in adding to my knowledge base. I really do like learning.

Dances, I think strain is measurable. with a strain gauge.
Therefore is strain a measurable consequence of stress?.
is Yield the point where strain is no longer proportional to stress?.
What happens to a strain gauge when the stress exceeds the yield.?
And I have never got my head around "proof stress". But thats another story.

To myself, Jim C summed up the question well. The rods dont fit. Dont matter how strong or tough, if they dont fit, end of story.
fellas, thanks again very much. Aussie bradley
 
lcrken said:
Agreed, the bolts in the R&R rods are 190,000 psi UTS, but the rod material is only 90,000 psi. The Carrillo rod material is 195,000 psi UTS, and their bolts are 220,000 psi UTS (H-11 tool steel). For additional cost they will provide bolts in a multiphase material at 285,000 psi UTS. We could argue about whether you need all that for a Norton, but there's no real argument about which is stronger and has more long term durability under hard use.

I think what bothers me about the R&R rods is this statement on their web site

"Unlike a forging in which the aluminum is literally pounded into the shape of a rod, our material is cold worked, forced through a die at extreme pressures, to form the billets from which the aluminum rods are CNC'ed from. This work hardening builds the strength, grain structure, elasticity, and general characteristics that makes our aluminum rods superior to common forgings. Our alloy is then further artificially aged and heat treated, then stress relieved though additional manufacturing processes."

I think that is a bit misleading. The usual benefit claimed for machining from a forging is that the grain flow is in the shape of the final product, so you're not cutting across the grain as much in machining as when starting from a billet. I'm willing to accept that R&R use a very high quality material for their billet, but that doesn't make it as good as or better than a good forging in similar material.

Let me insert a little disclaimer here. I've had great luck with stock Commando rods in both street and race bikes. In the race bikes I had them shot peened and regularly checked for cracks. I also check for cracks before I use them in a street bike engine. I've never broken a stock Commando rod, but have retired one or two with cracks around the pin end. But those were from regularly flogged race bikes. I have no hesitation to use stock rods in a street bike engine. That's what I ran in my 920 engine on nitrous last year at Bonneville, and they still look good. Still, I'm going with Carrillos for the next race build. One less thing to worry about.

Ken
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Gidday Ken, Thanks mate.

On re-reading your stuff the penny dropped. Maraging steel, .
thats the trick. I did not know it was used for bolts.
. This steel alone would make a good educational post. Any comments welcome
best wishes bradley
 
B.Rad said:
Gidday Ken, Thanks mate.

On re-reading your stuff the penny dropped. Maraging steel, .
thats the trick. I did not know it was used for bolts.
. This steel alone would make a good educational post. Any comments welcome
best wishes bradley
Click to expand...

Hi Bradley, maraging steels are used for some high strength fasteners, and are now pretty common in aerospace and race engine applications. We used them for some missile applications over 10 years ago, back when I was still in that business. Both ARP and SPS make a variety of fasteners using maraging steels. But in Carrillo's case it's the rod material that's a maraging steel. The rod bolts are either H-11 tool steel or Carrillo's own "Multiphase TM" material. They don't specify what their Multiphase TM material is, so we don't know a lot about it. Judging by the name, it's probably a high nickel and cobalt alloy, but there's several of those available. I did see a comment in an article about Carrillo rods that Cosworth uses that says their Multiphase TM alloy includes niobium. If that's true, it eliminates all the common multiphase superalloys I'm familiar with (which isn't saying all that much!).

There's a nice summary of current high strength fastener materials in the automotive high performance industry here:

http://www.enginebuildermag.com/2008/09/fastener-facts/

For enquiring minds, there's lots of good literature on fasteners available here from SPS:

http://www.spstech.com/product_literature/

Ken
 
B+Bogus said:
R&R aren't alone in believing alloy rods have a place...
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Aluminium rods are okay as long as you remember that there is no fatigue limit on them. On a race engine the rev profile is generally known - much better than on a road engine - and thus the fatigue-induced life span of a con rod can be estimated relatively well. And thus it is possible to determine when an alloy con-rod needs replacement. Race engines are rebuild regularly so there is a point in alloy rods simply because they will simply not see their "counter" running down to zero.

On road engines it is a slightly other story as the rev profile is far less known and times between rebuilds are longer and therefore not subject to routine schedules.

That's why aluminium rods have a place in racing today but no longer in volume production road engines. Actually F1 might be running MMC conrods today - where the MM actually stands for aluminium - because this stuff offers really good characteristics EXCEPT in terms of fatigue strength. However F1 engines aren't rebuild regulary after each event like they used to do about a decade ago plus MMCs have simply been ruled out by tse French lawyers. In the 200x-years the six F1 engine manufacturers where building and rebuilding a few hundred engines each year. Not it's only a handful and this actually prohibits aluminium conrods. Similar story for NASCAR: They rund steel conrods because they have to.


Tim
 
I'd be extremely surprised if F1 engines weren't all running Titanium conrods ?

Heck, they were back in the 1950s, if they were serious about winning.
It was said back then a Ti rod for a manx norton cost more than the rest of the whole bike,
it really was unobtanium...

As strong as steel, and only 60% (is it ?) of the weight.
OR, twice as strong as aluminium, and only a xx % (? ?) weight penalty.
 
Rohan said:
I'd be extremely surprised if F1 engines weren't all running Titanium conrods ?
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Only because the rules prohibit more advanced materials and Titanium rods are at the end of their evolution and thus dirt cheap in F1 terms. F1 has become effing boring in this respect. About a decade ago there were engines with ceramic roller bearings virtually everywhere instead of plain bearings - and then ceramics were banned. There were fibre reinforced engine components either with plastic or metal matrices - and then homogenous materials were stipulated. As soon as one of the engine manufacturers started to explore something new one could rely on the FIA banning it before it hit the track.

The current engines are a nightmare in terms of sensible engine design. In the V10 aera some engines were running 72deg bank angle because of ignition spacing, some 114deg for a good CoG and some 90deg for a good compromise. Then 90deg were stipulated for the V10 and the V12 was completely banned. Now the engine rules demand a 90deg V6 with no crankpin spacing (instead of allowing a free choice which would probably lead to 60deg and 120deg engines depending on engineering descision and not only rules). Plus there is a single Turbo the axis of which has to be in the centre plane of the car. Okay, this could be turned into a nice layout with a "hot V" (exhaust to the inside) - and have guess, it's verboten to do so.

F1 engines are rubbish nowadays. The whole thing only works because all engine manufacturers must follow the same rubbish rules.



Tim
 
Rohan said:
As strong as steel, and only 60% (is it ?) of the weight.
OR, twice as strong as aluminium, and only a xx % (? ?) weight penalty.
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Aluminium has a modulus of elasticity of 70 kN/mm², titanium 110 kN/mm² and steel 210 kN/mm². The density is roughly 2.7g/cm³ for Aluminium, Titanium 4.5g/cm³ and steel 7.8g/cm³.

If you just do the quotient (and I don't care about the units now) this is 26 for aluminium, 24 for Titanium and 27 for steel. Usually it's the E-modulus which determines a design as usually stiffness dominates the catalog of requirements. It's an engineer's task to "distribute" the best material and - with a bit of oversimplification applied - titanium and aluminium are only better than steel if the effects of (area) moments of inertia come into play. For a conrod this can be the case but it is largely driven by the environment it resides in.

Therefore a steel cap which sees mainly tensile stress when the piston and upper conrod need to be decelerated together with an aluminium upper part which mainly faces buckling issues and thus benefits from cross section is quite a good idea.

Titanium conrod are better in terms of fatigue then again ...



Tim
 
Excellent concise summary above Tintin.

Furthermore, your statement below is spot on. This is why one uses aluminum rods in nitro burning dragster engines. With the tremendous chamber pressures and resultant forces, the connecting rod's major challenge is resisting buckling.

Tintin said:
...........an aluminium upper part which mainly faces buckling issues and thus benefits from cross section is quite a good idea.



Tim
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I tried to find suitable Aluminum rods but billet is unsatisfactory in my opinion and no Forged aftermarket aluminum rods are available - only billet and they are not as strong and end up needing more material and weighing as much or more on the small end that causes vibration. Titanium rods must have a bronze bush so you end up spending a lot more for a rod that again ends up weighing about as much on the small end as a bushless steel rod.

Below is a failed after market rod out of the Beautiful "Yellow peril" French endurance racer (see it on facebook). The problem with all alum rods is they heat up and expand - you get too much clearance and the slapping can ruin the shell bearings and break the rod bolts.

I gave up and went to Carrillos and there have been no problems.

Interesting billet rods - USA made
 
Tintin said:
F1 engines are rubbish nowadays. The whole thing only works because all engine manufacturers must follow the same rubbish rules.
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Thats a cheap comment.
~150 hp from each 250cc cylinder ain't mucking about.

Although the rules do seem predicated to killing innovation, development and competition...
 
Rohan said:
~150 hp from each 250cc cylinder ain't mucking about..
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That sounds a bit high for F1 engines of today unless you are referring "unrestricted".

I also hate to see innovation stiffled but understand the reasons behind. I don't necessarily agree with it but it is not my race organization.
 
Rohan said:
Tintin said:
F1 engines are rubbish nowadays. The whole thing only works because all engine manufacturers must follow the same rubbish rules.
Click to expand...

Thats a cheap comment.
Click to expand...

The F1 rules demand a basic engine layout which no engineer would come up with. Period. Compare it to the other high-end motorsport category, the WEC. Audi is running a V6 there which is comparable in terms of mechanical layout and chassis integration. It's a 120deg V6 with a hot V. Guess why ....

~150 hp from each 250cc cylinder ain't mucking about.
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That is not the point. The power output is only one aspect especially as the current generation of engines is fuel-restricted.

Although the rules do seem predicated to killing innovation, development and competition...
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And thus it's rubbish.


Tim
 
of topic re F1

it is called formula 1, they get to make the formula....

as with nascar and every other they also all have formulas. would be nice if the formula was engine = XX cc, overall weight = XX kg, length and width = XX m's, and the rest was wide open, now lets innovate, historically the best ideas get copied by everyone.

we even do it here...
 
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