During takeoff, the pilot heard a "pop" noise followed by smoke in the cockpit. The pilot elected to continue the takeoff roll and return to the airport; during the downwind leg, the smoke became severe. The pilot was able to land the airplane safely. Examination of the airplane revealed the engine, cowling, and firewall sustained fire damage. Additionally, the inspection revealed that a fuel injector/line on the number 5 cylinder was broken, and sprayed fuel onto the engine's turbocharger.