"The combined power of 24 DOLMAR chainsaw engines is fed into to a 5-speed Harley-Davidson transmission by a series of twelve toothed belts. For use in the Dolmette the engines were tuned and tweaked to deliver 5.2 kW of power (7.1 PS) at 10,000 rpm. Maximum torque delivery is 5.5 Nm at 7,750 rpm. When all 24 are combined, the result is a 24-cylinder power plant with a total displacement of 1.9 litres, a power output of 125 kW (170 PS) and 130 Nm of torque at the centrifugal clutches. Twelve engines are mounted in two rows of six on either side of the drive belt casing. Each engine is held in place by means of two threaded studs that normally serve to secure the guide bar to the chainsaw power head. The individual motors are coupled together in sets of three by means of a double-sided drive belt, making up eight modules in all. The individual engines are not rigidly connected; instead they deliver their torque through the centrifugal clutch that is a standard feature of every chainsaw."
And the video:
http://www.youtube.com/watch?v=DDWqJe1dCgY