Check my latest build. It has German counterpart of WEP : MW 50.
Although it works a bit differently from WEP: Instead of powering up at the cost of temperature/ engine life, it consumes MW50 stored in a different tank.

To learn about Funky Trees go here.

Throttle+clamp01(Throttle>0.99)*0.1

You could use that input for your engine, change the 0.99 if you want the WEP to activate above a different throttle value and the 0.1 to change how much power is added when using it.