4-Rib A/C Belt Tensioners

On LS engines, two automatic tensioners exist for 4-rib air conditioning belt systems. The two versions are identifiable by a 2-bolt flange for truck applications and a backside pulley, while car applications feature a single-bolt attachment and frontside pulley. The pullies are smooth as they press on the backside of the belt. These tensioners are not terribly stiff and were phased out starting in 2009 in favor of stretch-fit belts for A/C compressors.

6-Rib Serpentine Belt Tensioners

The majority of LS engines use automatic tensioners that attach to the upper passenger side of the water pump and use a ribbed 6-rib pulley for the serpentine belt system. There are unique offsets, pulley diameters, and tensioner sweep angles for different car and truck applications, see measurements in the guide image below.

LS4 engines found in front wheel drive applications used an axial spring and a bellcrank (pivoting arm) to tension the 6-rib serpentine belt.

LS9 engines found in the ZR1 corvette use a smooth pulley to tension the backside of the 6-rib accessory belt similar to the Colorado 5cyl tensioner used in various ICT Billet bracket kits.

8-Rib and 11-Rib Supercharger Belt Tensioners

The tensioners used for the supercharger belt on LSA (8-rib) and LS9 (11-rib) applications are very strong units designed to minimize belt slippage.

What this means to you?

Tensioner models must be coordinated with your front accessory drive system to ensure proper alignment to keep your belts in place and proper tension to ensure proper accessory functionality.

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