i recently removed the venturi of cng, instead placed the cng pipe directly on the opening of the throttle body. but after installation cng mileage has decreased by about 20-25 km. pick and acceleration is more or less same on cng but petrol performance has increased since the constriction due to venturi is no longer there.
i do not understand why this arrangement has decreased the mileage. previously it was doing rs. 4.5/km with ac (around 140km on rs.630 refill) whereas now it's doing rs. 5.5/km with ac.
P.S. i have installed a corolla throttle body on the air intake in order to control the air intake opening from the cockpit