I’ve been looking for a tensioner for the supercharger for a while. The primary issue is that no one provides any dimensions or specs. Even the aftermarket suppliers only indicate car compatible and something like “50% higher spring rate that he OEM version.” So I had to purchase multiple tensioners to figure out what would work. The requirements were:
Automatic; spring loaded
Designed for high-HP supercharged engine
Clockwise rotation when pulley is located above the body
Fits my application
From left to right: LS7, LS9, LSA and Hellcat
The OEM LS7 tensioner is what was provided in the Harrop supercharger package and it’s a joke for a high-HP supercharged engine. The LS9 tensioner, like a U.K. power plug, is comically large whereas the LSA is a reasonable size. However, both the LS9 and LSA tensioners would require me to orient the body above the pulley which won’t work in my application. After running out of LSx options I tried a Hellcat tensioner. It meets all of the criteria and it’s used on Challenger SRT Demon which, at 808 HP, has the highest HP of the lot.
I then upgraded to a Hellcat racing tensioner from American Racing Solutions, so that’s a total of five tensioners LOL. It’s almost a pound lighter due to the pulley being billet aluminum vs. steel and the spring tension is almost double.
Hellcat OEM tensioner (left) and American Racing Solutions aftermarket tensioner (right)
Note the flat black spring sticking out of the top of the OEM tensioner (left) vs. the large round silver spring sticking out of the middle of the ARS tensioner (right)
I also upgraded to their ceramic silicon nitride ball bearing option. According to their website, they have the following advantages over steel bearings:
40% less weight
35% less thermal expansion
50% percent less thermal conductivity
Greater hardness resulting in at least 10x greater ball life
Non-corrosive
This reduces centrifugal loading and skidding, so they can operate up to 50% faster than conventional bearings. This is important in my application because I’m going to run a massive super damper which will result in a higher pulley speed, more about that later. The next step is to fabricate a custom bracket.