Find out why titanium connecting rods are just loved by motorists
Titanium connecting rods are one of the automotive components that were designed and created specifically for the high stress factors and the need of maximum performance that is encountered in the automotive racing industry. They haven’t left the racing arena insofar, with the possible exception of the perfectionist amateurs and of some high-profile, high-priced, high-speed street cars such as the Acura NSX, Corvette or Porsche GT3 that were reported of using titanium connecting rods.
But in truth the prohibitive cost of the titanium metal compared with the needed capabilities of day-to-day driving, makes titanium connecting rods in a common car an expensive, exotic and unnecessary choice.
The function of a connecting rod in a modern internal combustion engine is to make a connection (doh…) between the piston and the crank in order to transform the linear motion generated by the piston into the rotating motion that is further transferred in the wheels.
The most important stress factor that a connecting rod must resist to is the reciprocating load generated by the movement of the piston inside the cylinder. At every engine rotation, the connecting rod is stretched and compressed, and there is a multiplication factor for the stress correlated with the engine speed.
Titanium connecting rods advantages are not apparent at low speeds of the engine. Usually, the difference becomes noticeable in engines operating above 5000 RPM, noting that mass production cars engines usually run at 3500 – 4000 RPM.
But for engines speeds that surpass the 5000 RPM limit, the advantages actually increase proportionally with the speed, and for values that are around and above 10000 RPM – which is not unheard of in high speed racing competitions engines, titanium strength to weight ratio provides tremendous capabilities that are visible in the actual engine power that is converted into force and speed.
On a 300 HP engine, the weight saving alone generated by the piston not needing to expend energy to carry the rod itself up and down at each cycle, makes a difference of 35 to 50 HP for the same cylinder capacity. More power, for the same size, and fuel savings – even if this would matter little for the professional motor racer.
Not to mention that the inherent strength, durability and toughness of titanium, associated with the passive corrosion resistance makes the titan connecting rods more reliable, leading to fewer critical failures – which would matter a lot for the professional motor racer, especially if he is two laps away from the finish line.
There are three factors that the professional racer should consider when deciding about purchasing or ordering titanium connecting rods for his baby, assuming that he settled for the high-price and tries to achieve high-speed and high-performance.
First, titanium is a very sensitive metal to scratches. Scratches degenerate into cracks, which would subsequently lead to engine failure. Second, titanium presents an increased tendency of galling. This influences negatively the amount of tightening that is possible for the connecting rod’s bolts. Both of these two potentially negative aspects are controllable by polishing and coating the titanium metal.
A third factor, that is not as easily manageable is the first two, is the difficulties encountered when
Usually, the professional connecting rods are forged, in order to maximize the strength and toughness. This is not as easily applied to titanium, and most connecting rods made of titanium are usually cut from billet in order to keep costs at least at acceptable levels.