CONNECTING RODS

Connecting rods are a highly stressed component in high speed spark ignited engines. Connecting rods (a.) transmit the forces that the products of combustion exert on the piston to the crankshaft to create rotating shaft power, (b.) accelerate, decelerate and guide the piston up and down all the way to the maximum engine speed (c.) provide a bearing surface for the small end piston pin to pivot from, and (d.) house the bearing that connects this part to the crankshaft. High performance connecting rods need to be strong, light and stiff.

From previous discussions (see crankshafts), there is a component of the mass in any connecting rod which contributes to the reciprocating load of the engine. Since the linear acceleration and deceleration of the piston assembly (by the connecting rod) result in forces that the connecting rod and the crankshaft have to withstand, there is a desire to minimize the weight (mass) of these parts. The use of exotic materials like alpha grade Titanium or a metal matrix composite or high grade steels allow connecting rods to be successfully manufactured with a lower mass yet also meet the mechanical requirements of the engine system. As a result, engine systems which use lightweight connecting rods will have a lower polar moment of inertia which will actually not generate higher power output in steady state (like power measured on a dyno), but the engine will accelerate faster (have an advantage in transient response).

The Elite connecting rods for the Silver systems are all made from high grade steel and to Elite geometric specifications. The Gold and Platinum engine systems can use either Titanium alloy, special metal matrix composite alloys for the connecting rod or high grade steel. The titanium and metal matrix connecting rods (along with the ultra-light Elite pistons) are the principal reason why Elite engines of the top tier are able to operate at much higher engine speeds reliably and safely.