ALUMINUM VS STEEL
The forever on-going debate and seemingly the most discussed topic in the high performance world. Shall we even go there? Sure...but we'll intro this section by saying this is OUR opinion on the subject.
Aluminum rods act much like a "shock absorber" under load and will suck up the pounding the piston is transmitting to both the crank and bearing during the power cycle. Especially on the exhaust stroke when the bolts are really being put to the test as they have to hang onto that rod for dear life.
Aluminum is good!
It is for this very reason (along with a lighter rotational assembly) why EVERY blown car, nitro, Top Fuel, Modified or otherwise use aluminum rods...they relieve a lot of the stress the bearings see in these crazy HP steroid monsters because of the rod's shock absorbing qualities.
Again, aluminum is good!
But as with anything in making HP, there's always a price...the rods are changed out often. But at this extreme power level, the performance advantages gained are well worth the cost and maintenance for these guys.
KITTIE YOGA STRETCH
Yes, these rods will stretch. Guess what? Steel rods do as well. Let’s do a little record straightening here…
ALL connecting rods stretch when under load…albeit aluminum stretches about .010″ more than steel (mostly due to the higher expansion rate of aluminum over steel). But both alloys will return to their original size when the load is removed. The point they don’t return to their original size is when the metal has been fatigued beyond its limitations. This is called deformation. Much like when a bolt has been stretched beyond its yield…the bolt will not return to its original length. Junk it…it can no longer do the job that it was designed to do.
So backing up a bit, why does a Nitro car change its rods only after 10 passes? That’s because the rods have been stretched to the point of no return. Major pounding…major RPMs…Mach 1 speeds. The rod has now seen its limitations to maintain its dimensions. Junk it…it can no longer do the job it was designed to do.
This “stretch” is inherent to all extreme power makers…a known fact with builders and nothing new and/or mysterious. How to combat this? When we designed our rods, we accounted for this stretch by designing the C-to-C length .010″ under, so when assembling, their expansion actually will NOT have to be accounted for when setting your piston-to-valve clearance. Brilliant!
HOW LONG DO THEY LAST?
Somewhat of a loaded question with many answers. We’ll speak it as we see it. It really is very simple.
The amount of life you can get from an aluminum rod is entirely up to the application you’re using it in. Folks tend to group all of these apps into one. Not a fair nor accurate thing to do. Don’t be an ignoramus.
A blown alcohol car will possibly get around 20 passes with a set of aluminum rods, a 4000 horse 1/8 mile big tire car around 60-75 passes and a little bracket racer car could use them the entire season…and oftentimes using our rods, for multiple seasons. Lastly, a weekend tinker toy with quick jaunts to the local drive-in and/or midnight drags could last 20k plus miles.
Bottom line: It all really depends on how hard they are being pounded on. It's really all relative.
The bottom bottom-line: With all factors being the same, be it a bracket car or a good ol’ boy farm truck, these rods are THE industry leader when it comes to longevity for their chosen application. Period.
End of story.