You wonder how the old motor could hold up to the power output, although I know some members posting here have run Drouins with success. I suppose if the available power is used sparingly or occasionally the bottom ed might hang in there.
Steve Maney commented that years ago he hit a "wall" with his Commando racing engines at about 135 MPH. If he tuned the bike for higher horsepower and more speed than this the Crankcases broke apart. This is why he developed his Maney crankcases.
That 135 mphtop speed and matching horsepower output would be a long way below the power output shown in the Drouin Norton ads of the day. I believe they show about 105 hp for the Norton 850.
130 MPH is about what modern day racers seem to get from about 70rwhp (Doug Mcrae's Herb Bechker built engine)and I'm sure those motors are heavily fortified to stand up to that. If the Drouin was used on a standard motor to produce 100+ hp and the hp was actually made use of in a substantial way, it seems to me the motor has to detonate is fairly short order?
Glen
my Norton manual has the high preformance section at the back and it has a pic of the Drouin kit in it, I have built my Norton engine with some of the modes that they recomended.
