Harrop Stage 2 Pulley Tensioner Failure

I’ve got a 2021 LX570 with a Harrop TVS2650 kit, 650cc injectors, 80mm Harrop pulley, 84mm RCF throttle body, and a custom Yotawerx tune. When the shop finished install of the kit and tuning, the tensioner pulley failed when they were doing some testing. At the time I didn’t think much of it, but after about 700 miles driving on the setup the belt snapped and pulley tensioner failed again. It did fail during a wide open throttle pull in higher RPM. I’m running the Gates K081177 belt provided by Harrop that’s supposed to be compatible with the smaller 80mm pulley.

Have any of you experienced something like this or would know what could be the source of the issue? I did some digging online and haven’t seen anything about tensioner/belt failures on a similar setup. Any help is greatly appreciated!

 

I have the magnuson 1900. I put on a smaller pulley (used same belt), waited a year then put on a tighter belt. After 1000 miles at least one idler pulley was destroyed (loud whine). Seems related to me that these tighter belts tend to destroy the bearings and or tensioners. I went back to the regular sized belt and have had no issues/no boost loss.

 

Harrop provides 2 idler pulleys (one on water cross-over pipe, and one on a dedicated bracket), the tensioner is stock Toyota. I have just replaced my idler pulleys after 4.5 years because they weren't spinning freely.

 

Unfortunately for me, these failures all occurred with the Harrop supplied Gates K081177 belt. I called both Harrop and Prospeed asking if they’ve seen tensioner/belt failures and neither of them have seen failures like the one I am experiencing. They also both confirmed that I should stick to the supplied belt. Leads me to believe the failures are caused by something else… still having my shop diagnose