The best of the worst involving catastrophic Connecting Rod and Camshaft failures...

One of the most common reported engine failures revolves around the all important connecting rod. The incredible forces the connecting rod is subjected to is amazing. The up and down, back and forth motion is best visualized by someone grabbing you by the collar, and shaking you back and forth. As the RPM increases, the forces on the rod accelerate in an exponential fashion. This "magical" number both mathematically and realistically begins at 6,000 rpm's. Besides the internal mechanical forces being exerted on the rod, some of the commonly seen failures is an operator unknowingly continuing operation of a motor with a bent rod, soon resulting in catastrophic failure. Usually the origin of failure is unknown, since the inevitable total destruction covers up the true origin of failure. The photo to the right illustrates a rod being bent after getting water in the cylinder, thus "hydraulicing" the piston near top dead center, easily bending the rod into mechanical submission....

Even though the above rod is severely bent, it still did not fail entirely by breaking apart. Subsequent damage may have been  diverted by the precautionary preparation of this high performance rod during it's original rebuild, including high performance rod bolts, polishing of the beams as well as shot peening and stress relieving. If the rod would have broke, the horrific aftermath would look like the piston in the photo to the left. The beefy connecting rod ripped in two right at the top of the rod. Parts were strewn everywhere, and the end result meant all new parts top to bottom, including a new block and heads.  This particular failure was caused by increased friction at the piston pin at high rpms, whereas the overheated and seized pin restricted the back and forth rod movement to the point of failure. Bushed rods and full floating performance wrist pins can minimize this potential problem when operating engines in a high load or high rpm environment.

Other Rod failures include the rod itself giving out. Sometimes this is a result of metal fatigue, over stress, or even at the hands of a spun rod bearing wreaking havoc on all that it touches. This particular situation in the photo on the right shows an incredible rod failure due to excessive rpms and too much horsepower for the components being used. Note the high performance bolts still were doing their job, but the weak shoulders of the big end of the connecting rod (yellow) gave way first, and from there it went down hill fast.

Performance connecting rods minimize this failure by making the rod out of better premium materials, and improved beefier
designs with extra metal in all the right places. Connecting rods are the first vital concern in an automotive engine, while the crankshaft is second, valve train third and pistons fourth.