Cheers guys.
Suppose I should ask, as Simon mentions the Walbro is OK upto 450 bhp.
I have a calculated 430-440 BHP based on the calc for 4 ( no. injectors ) x 850 (flow rate mm/min ) x 72% ( injector duty max ) divided by 5.5 ( mls per hp ) . TD05-20G at 1.65 bar - 1.70 bar boost. Broke the gearbox recently after 2 years of 363 bhp/325 lbft!
Is this calc about right?
It was spot on for the last turbo / injectors at 360 when measured 3 times on 2 rolling roads over 18 months at 363 bhp/325 lbft. ( 550 injectors at 91% duty, TD05 @ 24 psi )