720D powerboost

Good luck

Boring 125 thou only adds 15.15 cubic inches. Overboring lets more heat out to the water jacket instead of being used to expand gases and build pressure in the combustion chamber on top of the piston. A 720/730 is rated about 58HP or 0.154 HP per cubic inch. If the heads could fill the now larger combustion chambers as efficiently as before and minus the extra heat loss then fuel flow could be increased to achieve an whole 2.33 HP before overfueling. Boring alone won't add noticeable power unless you sleeve it out to half an inch from the head studs. Rather than boring 125 thou for power alone far more can be had with increased airflow with more fuel . The oilbath aircleaner is a restriction at the best of times and worse when filled with 42 to 45 years of oily mud. Albert at Renaissance 1-360-748-0026 has the most horsepower per $ spent available. A few more RPM up to maybe 1500-1600 if the valvetrain has fresh springs will move more air and fuel through the engine per minute. A straight pipe through the middle of the muffler will improve breathing as well. Some tractors sport a exhaust stack straight up from each head exhaust port. Some head work with larger valves, porting and a little more camshaft will also move more air.