speed boat

Hallo, Please allow me to write in english I just motorize a riva aquarama special 87 cm (scale 1/10), its max speed is 45km/h; while the real riva aquarama's max speed is 68 km/h. How to make a mahagoni riva aquarama conquer the speed 68 km/h? Anyone here make mahagoni boat run faster than...