The difference between the American Racing Solutions HEMI Race tensioner on the right, and the OEM style tensioner on the left is like night and day. The ARS unit has a billet aluminum pulley compared to the plastic pulley on the OEM unit. Note the mounting bolt hole pointed out by the red arrows, the OEM unit is a very thin wall construction prone to flex on high output engines compared to the very beefy wall thickness of the ARS unit. The yellow arrows show the deeper billet locating pin on the ARS tensioner and the blue arrows point out the size and strength of the ARS round section spring versus the thin, flat ribbon of the OEM style tensioner.
The overall robustness of construction of the billet American Racing Solutions HEMI belt tensioner is why it works so well. It is imperative that the serpentine belt remain absolutely flat and parallel to the pulleys and itself for its entire length even when stressed at high RPM on a performance HEMI engine. The slightest amount of twisting, bending or other flex can cause the belt to “walk” fore or aft on the pulleys — that’s when the belt ends up breaking. As you can see, the OEM-style tensioner on the left, while perfectly fine for stock or near-stock engines, is constructed with very thin sections of inexpensive cast aluminum. One look at the all-billet ARS unit on the other hand inspires confidence that it will not flex even under the most extreme usage.
The brute strength of the ARS tensioner versus the OEM style is everywhere. The red arrows again point out how much thicker and less prone to flex the mounting bolt hole is. The OEM unit on the left has very thin walls on the tensioner arm at the spring unit (yellow arrows) and has the minimum amount of metal needed to perform on a stock engine. The blue arrows point out the ARS tensioner’s 1/2” breaker bar opening for belt changes versus the factory 3/8-inch size, as well as the square end of the tensioner arm. This clever feature lets you use a 15mm wrench (or a large adjustable wrench) to relieve belt tension when removing or installing a belt.
American Racing Solutions
Phone: (888) 427-1003