Modified Outboard Racing allows and encourages modifications to the engines used, though always within strictly enforced specifications. Typical modifications include enlarging and polishing of the intake and exhaust ports and passages, adding tuned exhaust systems, balancing of engine parts, and the thinning and re-shaping of the gear cases. Custom built tower housings (the part of the motor connecting the powerhead with the gear case) are also allowed. The only significant limitation is a fuel restriction calling for pump gasoline and two-stroke oil. Power boosting fuels, additives and alcohol-modified fuels are illegal.
Modified racing challenges the driver to develop engine technology to the fullest. The opportunity to maximize power output gives the clever engine builder a speed and acceleration advantage over the competition--an advantage not shared by stock outboard drivers.
As in the stock outboard category, classes are defined by engine size and hull design. There are presently sixteen classes that comprise the Modified Outboard category. The two hull types used in Modified Outboard racing are Hydroplanes and Runabouts. These hull types never compete against each other, although during open testing periods they may occupy the race course at the same time. Speeds in the Mods range from 55 mph in the Formula A class to 90+ mph in the Formula E class.
Read some info about one of SOA's newest classes, Formula E Runabout, in their own class newsletter.