Leafy

iTrader: (1)

Those rods look like a piece of art. I just have to wonder what the effects of having a less stiff connecting rod has on an engine. How do I know they're less stiff? Because the rod isn't ~3 times as thick as a steel piece. You can make them not fail with good geometry and engineering but I don't think you can make up for the stiffness difference. So these rods are going to stretch more at tdc (not necessarily a bad thing) than steel rods and compress more under the power stroke. So they increase compression more as rpm increase (due to more and more tensile loading) compared to steel rods, that also reduces valve clearance and get the piston closer to the quench pad. But what does that extra compression deflection do to the power stroke? Soften the blow of each ignition event? Because you do eventually get most of the energy used to compress the rod back, just lose some to heating up the rod. Of course both of these deflections could be an order or magnitude smaller than I think they are and have a barely noticeable effect.

triple88a

iTrader: (2)

It doesnt say that they are forged anywhere either.

y8s

iTrader: (8)

could be the word "buddy" being thrown around like you his bff.

a small heads up that any perception of an attitude on this forum will eventually devolve into you leaving and threatening to never do business with this forum again.

and the forum will happily forget about it and move on to harassing the next tough guy.

(this is less policy than inevitability--welcome to miataturbo.net)

Scrappy Jack

iTrader: (2)

darren

Hey buddy. Thanks for the kind words! We're excited about them as well!

Let me educate you a bit on Al rods and their affects inside the motor. To put it simply...and briefly:

All Al rods are basically a "shock absorber". They lessen the stress on the crank and bearings because of this. Steel rods are like a jack hammer when you're really pounding on the motor.

Al rods do stretch but only under load. Steel rods do as well...albeit not as much. We also build them .010 under in C-to-C length to make up for this growth under load. I mean LOAD...extreme stresses...lots of HP. Not with Joe Bob's little street cruiser.

This is a known fact with builders...nothing new. We just side-stepped it a bit with the design of its length.

I address these things quite a bit in our description of the rods on our page. You should check it out.

Thanks again buddy.

darren

That's because they are NOT forged. They are billets made from bar stock.

Any comparison to BME is not only unfair, but not accurate.

Apples to oranges my friends.

hustler

iTrader: (6)

Get ready for a long, tearful response.

hustler

iTrader: (6)

Does the material shorten life compared to a steel rod? Is anyone doing "real racing", known as "endurance racing" to most, with these rods?

darren

True that...if people within the forum can't handle what I have to say in the only way I know how to present it, then I suppose that will be the case, yes.

What would people rather have? A slick talking sales guy with no idea of what they're talking about with the only goal of pulling out your wallet to grab the dead presidents? Or a guy that tells it how it is with no BS. If it were me on the "buying" end, I'd rather have the latter.

I'm just here to answer questions and share my experiences. If any info isn't wanted, then yes, I'll move on.

Leafy

iTrader: (1)

Hussy, they're aluminum, even if you don't exceed the yield strength of the rod, it will fail, eventually. All aluminum parts will fail if they see cyclic loading because, unlike a steel parts, Al part cannot be designed for infinite fatigue life. Honestly it doesnt concern me too much in a race engine. But if you wanted to see if these could live for a 25 hour race, and you were serious, you would put them in the FEA software, put in the exact S-N diagram for the material, and use your previous data log from the race to make a accurate simulation of what the rod is going to have to endure to last a race. And its going to take a long time to run.

Darren, you guys put a lot of parts handling into these. From what I gather from your process they're in and out of the machine a bunch of time. I'm surprised they're only $800.

hustler

iTrader: (6)

Respect is earned here. We have people here winning every class they enter in every race designing parts for us troglodytes with green-backs. Telling us how it is and demonstrating the results are two different things. Put that rod through a few 25-hour enduros at 150hp and it will garner some respect.

darren

Damm! FINALLY someone "gets" it! lol

Thanks Leafy for pointing that out. Nothing is perfect...everything breaks, fractures, sags and wrinkles.

Imagine a soda can that you bend back and forth a number of times...what happens? It breaks. This is a simple analogy, but it holds very true to any part used in the motor...including Al rods. This is call "deformation". There is a fatigue life involved here.

But hey...it's called RACING. The benefits of using the Al rod far outweigh the cost and maintenance.

Oh yeah man...the rods are removed out of the machine a few times in order to have them look the way they do (thanks for seeing that...nice eye). But the price we have currently is an "intro" price. It will go up in a few months I predict.

darren

Granted...but I'm telling you "how it is" with our rods. Not suggesting how you should spend your money.

I'd love to see how they do in endurance racing! All someone has to do is step up and give it a shot instead of debating the subject. My area has always been drag racing and that is where Al rods are mostly used. To use them in such a way would be quite interesting to see.

I'm not trying to earn respect here...just trying to point out certain things to have you guys on the right track when talking Al rods. Nothing more.

hustler

iTrader: (6)

A riding crop will also get you respect here. Most of these dudes are subs.

darren

Got one handy? I broke my last one with my wife.

TurboTim

iTrader: (9)

Hey buddy. Forgings which are then CNC milled are better than bar stock which are then CNC milled.

Our metalurgist doesn't work on Fridays so I'll have to wait until Monday to run it by him, but my general understanding of cryo on aluminum from back in my academia days is that it's beneficial when you do something that adds internal stress, like welding it. No appreciatable increase in yield strength of parent material. But your alloy may be different and actual testing trumps all. There's still a lot of voodoo in some heat treating processes. Coincidentally I was at one of our heat treat facilities yesterday because of that. Horray proprietary heat treat processes.

I also wonder at what temperature does the benefits of cryo fade.

You made the part weaker so that it's easier to install. I think that's failboat buddy. I'd rather have a stronger part and machine clearance for it, personally. But I can appreciate the desire; at least once I month I get a crybaby complaining that he has to swap sockets on his ratchet because the hardware on this rocker stands are not all the same size. They would rather have all the same size bolt (and therefore the smallest/weakest bolt) and compromise on the assembly strength than swap the socket or grab another wrench.

You are correct that aluminum absorbs the shock...this is mainly why top fuel run alum rods. Those run ~7800rpm. Prostock and some Promod guys run steel rods due to the rpms they see. That's direct from the engine builders.

But when an aluminum rod breaks, significantly less damage is done, or so I've heard. Often the engine could be repaired and run the same weekend. Steel rod breaks and it takes out everything.

hustler

iTrader: (6)

It's all dudes here, better lube your sigmoid.

Leafy

iTrader: (1)

If the rods get above the temp where the grain structure of the metal starts to see changes which I forget what it is, for some reason 600*F sound familiar for aluminium. You'll loose the benefits of cryo treat pretty quickly. They also use vibratory stress relief, which is something we only spec on welded parts (and only because its cheaper than stress relieving with heat, which we do on more critical parts).

On the aspect of forging, as I understand it it completely depends on how they are forged, forging will make the material more directional in its strength properties. IE if you forged the rod one way you could make it stronger along its axis but weaker in bending. Cold formed bar stock is going to be less directional and hot formed even less than that. So if you need a part to be strong in multiple directions, something machined from hot roll might actually be better.

darren

That is rather close Tim!

Let me address this:

First, its Coke and Pepsi when it comes to "which is better...forgings or billets". I'm not going to debate it any further. This is what we chose to use.

Second, cryo processing only "fades" if a rosebud hits the alloy.

Third, we did not weaken the part by making it easier to install...and I'm quite surprised you would say that so pretentiously. That wold be stupid to do that. Do you think we like people coming back to us pissed off?

We did lots of stress analysis to come up with the best balance we thought for the situation of being "builder friendly". I'm not going to say it's perfect for everyone's platform and/or scenario...as that would be impossible...but at least we're aware of the building process when designing and using Al rods.

Beef rods are not necessarily the strongest...there are many other factors involved. I've seen them break just as easily as a China built steel rod.

Regardless, we feel we've got a really good balance between the two...strength and the least amount of frustration for the builder when using them.

BTW...don't know in your neck of the woods on what goes on, but there are plenty of Pro Stock guys that use Al rods my friend. We know because we've sold the the older versions to those guys all over the world for at least 15 years.

hustler

iTrader: (6)