You can actually make one yourself. I ran across some diagram when I had my MGB in the 80s. I had replaced the carbs with a Weber and tuned headers. I made a water injection bottle from a jam jar with a gasketed cap, 2" x 1/8" dia. copper tube that went thru the cap to just above the water level, and another 6" x 1/8" tube that went thru the cap and the water, to about 1/8" above the bottom of the bottle. I plumbed the short tube to a small hole in the intake manifold, and left the long tube as a vent that sucked air through the water, misted the air above it, and the short tube fed misty air upon acceleration through vacuum in the manifold. The car ran not unlike driving in the rain or heavy fog. Smooth combustion and maybe just a bit more power. Problem was...I'd forget to check and ran it dry a few times, burnt a valve. Interesting experiment but expensive lesson.
