The Apex Garage: Blueprint of a Custom Turbocharged CB750
Building a street-legal 160hp turbocharged cafe racer out of an air-cooled 1978 Honda CB750 SOHC engine requires precise thermal management, custom oil feed plumbing, and high-tensile frame reinforcement.
Phase-by-Phase Fabrication Log
The original dual-rear shock setup was removed. We fabricated a central chromoly hoop and integrated an Öhlins TTX36 rear shock from a Triumph Daytona 675. Rake angle was adjusted from 27° to 24° for faster cornering initiation.
A custom 4-into-1 stainless steel exhaust manifold was TIG-welded to route exhaust gases into a compact Garrett GT1544V variable-geometry turbocharger. Boost pressure is regulated via a 38mm Turbosmart external wastegate set to 9.5 PSI.
We replaced stock carburetors with a custom 34mm throttle body bank paired with a MicroSquirt standalone ECU. High-flow 440cc injectors provide reliable fueling under positive manifold pressure.
Dynamometer Tuning Results
On our Dynojet 250i, the completed build delivered 158.4 wheel horsepower at 9,400 RPM, up from the factory output of 67 HP. Weight savings resulted in a wet total of 162 kg, delivering a terrifying power-to-weight ratio.