Connecting Rods

Time to do some Push-Ups

  

The connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion. When the cylinder fires, the piston pushes down on the connecting rod, which inturn, causes the crankshaft to rotate. All connecting rods for automotive use need to be lightweight but strong enough to withstand and transmit the thrust from the pistons to an engine’s crankshaft, Speedmaster™ has a wide range of connecting rods ready to fulfill all your engine needs.

 

  • I-Beam 5140

    Tensile strength 115,000 Psi

    Speedmaster™ 'I' Beam connecting rods are manufactured from high quality 5140 steel. Perfect for Small Block engines producing up to 600hp, and Big Block engines producing up to 650hp. Featured in press-fit or full-floating.

  • H-Beam 4340

    Tensile strength 145,000 Psi

    Speedmaster™ 'H' Beam connecting rods are manufactured from aircraft quality 4340 chromoly steel that is far superior to the low-carbon 51-series steel. Perfect for SB engines producing up to 750hp, and BB engines up to 850hp.

  • I-Beam 4340

    Tensile strength 145,000 Psi

    Speedmaster™ 'I' Beam connecting rods are manufactured from the same 43-H aircraft quality 4340 chromoly steel but designed to be the most reliable in the racing industry. For an H-Beam to catch up to the compression strength of an otherwise comparable I-Beam, the H-Beam would need to be FAR heavier than the lighter, stronger and more efficient I-Beam design. Perfect for engines producing 1000+ HP.

  • I-Beam Billet

    Tensile strength 162,000 Psi

    Speedmaster™ forged billet connecting rods start with certified high-nickel 4340 aircraft-quality steel and are fully CNC-machined on the newest generation of equipment to ensure the removal of all surface imperfections. They are specially heat-treated using a multi-phase process to produce the ultimate in strength and reliability.

 

 

  • Quick Tip



    Connecting Rod Length

    When measuring connecting rod length, we’re really talking about center-to-center length—the distance from the center of the piston pin-end-bore to the center of the big-end bore. Here’s an easy method of measuring length:

    - Using a properly calibrated caliper, carefully measure from the floor of the pin-end-bore to the roof of the big-end-bore (the shortest distance from bore to bore).
    - Using an inside micrometer, measure the diameter of the pin-end bore.
    - Using an inside mic, measure the diameter of the big-end-bore (with cap installed and fully torqued to spec). Take this measurement from the 12 o’clock point (center of the rod saddle radius) to the 6 o’clock point (center of the cap radius).
    - Add to your first measurement one-half of the pin-end-bore diameter and one-half of the big-end-bore diameter. This is the center-to-center dimension.


    Horsepower vs. RPM

    When it comes to rod selection, which is more important: horsepower or rpm? Higher power levels increase the compressive force on the connecting rods while higher rpms increase the tensile strain on the rods. As it turns out, most rods don’t bend and fail on the compression stroke but are pulled apart at high rpm and break on the exhaust stroke. Consequently, rods need additional compression strength and stiffness to handle higher horsepower loads. But in high-revving engines, increased tensile strength is an absolute must for the rods to survive at high rpm.