Back in the mid 70's, I made one by copying what was available at the local speed shop. All the popular water injection systems at that time used a reservoir with a small electric pump ( I used a windshield washer pump from a F#$d ). The system required a triggering device so that you were only using it when there was a load. I used a vacuum switch that triggered at 5" Hg. I also used an adjustable metering device ( from a fish tank ).
That Rube Goldberg system worked like jack the bear, I was able to run regular gas in a 10.25:1 350hp 396 with the timing set aggressively, without any knocking or pinging. I even carried a camper, so engine was loaded on the hills. It was a great system, but my new engine is 9:1 and I don't need the extra protection and the hassle of extra maintenance. You don't want that system to fail, or it is bye bye engine!
Bob
