My electrolizer starts emitting vapor clouds within 30 seconds of starting. And by the way, my cells run cool. I have always postulated that this vapor cloud was the result of the "mechanical" action of the gas bubbling through the electrolyte then those bubbles popping within the electrolizer. All very similar to the steamless (sometime called cool mist) vaporizers they sell in drug stores.
1991 Plymouth Acclaim 3L V6.
1 dry cells with nineteen 6"x8" 316L ss plates, driven by constant current PWM set at 35 amps (13.3V at PWM). 28% KOH electrolyte. Total measured output 2.5 lpm. Mileage went from 18 to 26 mpg, all city driving (44% increase). EFIE set at .370 and I still need to play with ignition timing.