I recall 1800 rpm from a past search that led me into articles published by the manufacturer. There's so much conflicting info regarding the details, so I was just going with 1500 because it was mentioned earlier than my post in this thread. I will say that 1500 is the lowest threshold I've come across. 1800 is more commonly seen, but again, who knows.@Headbarcode I'm not sure about the 1500 rpm thing. Isn't the stall speed of the converter higher than 1500? That would mean it would stop helping before the converter hits. I'm not saying you're wrong, I just don't understand and that part doesn't make sense to me so I'm wondering. If it worked off wheel speed (the half rotation) that would make more sense with a converter.