Originally Posted by Stuart@VelocityAP

Hi Dennis,

The point that the gentleman in the video is making that is valid is - there are less problems with slippage if you upsize the crank pulley versus downsizing the supercharger pulley. As a general rule that's not wrong. It's particularly important on the JLR supercharged engines because the tensioner design doesn't allow much wrap on the upper pulley anyway. (It's also one of the reasons the belt needs to fit snug.) However, our Griptec pulley doesn't have any problems with slippage as we've verified through datalogging. This would not be the case with a standard steel or aluminum pulley without the coating.

Originally Posted by jahummer

I realize this isn't the X150 forum but have you the ability to offer one for the M112 fitted to the 2007-2009 XKRs?

Originally Posted by datriani

Hey Stuart

Sounds like there’s some confusion as to what changed regarding the details around any benefit for a smaller SC pulley on the V6 pre/post your recent GripTec advancement.

As I understand it, prior to GripTec technology a smaller pulley on the SC had some slippage at the higher RPM which negates any real benefit. But with the GripTec advancement, you’ve eliminated that and we’re able to see an additional 2 psi of boost.

The increase in RPM on the SC is slightly above the manufacturer’s specs but it sounds like the manufacturer understated it’s true tolerance… similar to our engine’s redline (6500 vs. 7000 with your ECU/TCU tune). So no issue with the increase but as with all mods, it’s also based on how hard you drive and push the limits of your car.

And you’re also saying (in other posts) that with the increase in boost, it’s critical to have high quality fuel to prevent knocking but otherwise it’s a safe and a way to get an additional 20 HP on top of the crank pulley/ECU tune.