I have built 4 alcohol stoves in the last year using plans from the Zen Stove website.
I have made the cat can stove and the min zen sideburner stove from this page Chimney stoves
I also have made this basic low pressure sideburner stove Sideburner stove
And I also made this low pressure top burner open jet stove which is the second stove pictured on this page Pepsi can stove
The side burner stove was the least efficient for me since I use a narrow bottom pot and the flames had a tendency to go up the sides of my pot and the heat transfer was not very optimal for boiling water. I designed a wind screen/pot stand from an empty fruit can and 2 bike spokes and with the pot a couple inches above the Top Burner stove, the flames hit the bottom of the pot and I could get a rolling boil on 20 ounces of tap water in a little over 7 minutes. It definitely helped to keep the lid on. So since last spring I have been using this set up at camp sites with excellent results. I cook Ramen and make morning coffee with this gem. Today I got the itch to experiment and I decided to re test my zen chimney stove against my top burner stove. I was surprised at my results. The open jet top burner stove was surprisingly INEFFICIENT compared to the zen chimney stove. This shocked me as I thought basic chimney stoves were supposed to be relatively inefficient compared to a stove that burned the vapor from tiny jets. I used a syringe and put exactly 3/4 of an ounce of HEET in each stove and lit them. I started timers for each one. At approximately 7 minutes and 6 seconds, the Pepsi can stove ran out. The Zen chimney stove kept burning strong and didn't run out until 9 minutes and 40 seconds!!! Can anyone tell me if this is common for these 2 stoves?
I would have expected the readings to be the other way around.
Here's a few pics of it in action last spring with my windscreen.