What choices do you have when choosing a wrist pin? Why choose one over another? Do you need a coated pin, or an “upgraded” material? Different applications and cylinder pressures, along with different piston and rod combinations play a huge role in selecting the perfect wrist pin. All of these components need to complement one another so the deformation of the components work in harmony.
Off the shelf pistons generally come with pins that match the intended power level of the parts they are being supplied with. But, CP Carrillo and Arias Pistons give the option to upgrade the wrist pin. If you plan on using a power adder, or making power on the higher side of the envelope, it never hurts to increase the wall thickness of the wrist pin, or upgrade the material.
There is a combination of things to consider; what is the pin engagement of the pin in the piston, is the piston a round piston or an X-Style piston (forged side relief), what kind of RPM will the engine see, how heavy is the piston assembly, and is the pin tapered or straight wall? When you know some of these answers, it helps the supplier help pick the right pin for your application.
Always supply the pin end width of the connecting rod, so the pin engagement can be designed properly and make sure there are no fitment issues. When we have the opportunity to design the piston and rod combination, we can determine if a smaller pin diameter is advantageous and go that direction when it’s a benefit.
In regards to coated pins, those are generally DLC (Diamond-Like Carbon) or WPC (Micro Shot Peened) and we offer both. DLC coated pins are used in severe applications or those that pull vacuum greater than 12 to 15 inches. When vacuum is created in the crank case, oil doesn’t stay on components as long as it would otherwise and can create galling in the pinbore of the piston and connecting rod.
Our experienced Sales Staff at Horsepower Direct is always available to discuss any of these options to make sure you end up with the right parts for your engine.