Re: gas mileage?
Depends on a number of things. First, you didn't say how far you went on those two tanks or how long you ran or how fast you ran. You have 80 HP, He has 90 HP. How big are your tanks, and how big is his. How fast did you run and how fast did he run. Your engine will burn roughly 8 - 9 gallons of fuel per hour at wide open throttle. His 90 will burn 9 - 10 gallons per hour at wide open throttle. His boat will probably burn less fuel at the same speed as yours because he does not have to have the throttle open as far as you do to maintain the same speed. In a nutshell, you are comparing apples to oranges. You don't have comparable boats. Those older engines were not economy champs. I have a 17 foot walleye boat with a 75 Merc. I also have a fuel flow monitor and at wide open throttle, two aboard, full live wells, etc., at wide open throttle the engine burns 7.5 gallons of fuel per hour.
