View Full Version : Pepsi Can Stove Boil Time
I was just curious as to how long your soda can stoves take to boil a pint of water. I've been reading a lot about it, and it seems that it should take 5 minutes. First off, is this a rolling boil, or the small bubble boil before the rolling boil? My soda can stove takes about 9 minutes to get to a rolling boil. Also, how much fuel does it take to get to the rolling boil? 2 TSB? Mine takes about 3 1/2 TSB. Am I doing something wrong? I used the Cobra stove directions here:
for it's ease of construction. Basically, sandwich 2 soda can bottoms onto each other, drill 16 1/16" holes around the ridge, one 3/32" hole in the center for a fuel fill, and you're done. I don't have fuel leaks, and I have a nice blue flame. I've tried varying the number of holes and the size of the holes, but it seems like my original stove works the best. Maybe I'm expecting too much from my little stove. What are your experiences with boil time and fuel usage?
I posted the below in TrailForums. Some other ideas...
With home Alchy stoves, the size of the holes you punch can make a big difference. You may want to experiment a bit.
What kind of pot are you using? Titanium works a bit better with alcohol because of it superb conduction abilities.
Were you outside? cold day? windy?
and knowing is half the battle
I made the Cobra stove the other day. I think it took me 15 minutes. Kudos to that. Here are my observations after my unscientific research.
I indeed acheived a rolling boil of 2 cups of water in my titanium pot in 4.5 to 5 minutes with the Cobra stove. I measured 2 tbs of alcohol with a tbs measure. This was in my kitchen w/o wind screen. I continued to time after the boil and my stove fizzed out after 8 minutes.
I then pulled out my trusty Pepsi can stove. The two walled design. Same kitchen, same pot, 2 cups of water, no windscreen, 2 tbs of fuel. It took about 7 minutes to reach a boil. The stove however, burned for 13 plus minutes. I got bored, sorry.
Doesn't that mean you can get away with less fuel over a long trip and carry a lighter stove (no priming cup)? You also get to simmer that rice for a little longer and make sure those Ramen noodles are fully cooked. Of course you may have to wait an extra 2-3 mintues for a boil, but I think GI Joe always won because they took that extra minute to plan a little better. Cobra Commander was just too rash about everything.
And now I know...
Thanks for the reply. I did testing in my kitchen, with no wind screen. The only thing that may have caused some variance that I didn't control for was the pot. I am still waiting to get my titanium pot in the mail. I used a regular 4 quart kitchen pot. I did some more testing and found that this kitchen pot took a little under 4 minutes to boil when it was over my kitchen gass range. That makes it sound like the titanium may reduce the boil time.
I was also thinking about using a pot cozy for simmer cooking applications. I'm not sure... Maybe I should just stick with the origninal pepsi can stove idea.
One thing to take into consideration is altitude. Over the last week or so I've made and experimented with several styles of homemade alcohol stoves, and found that the best I could do with any of them was a 6-7 minute full rolling boil. Without a pot lid I could not reach a full boil; also at least 3+ Tbs of fuel was required. (I used both denatured and HEET methyl.) So I bought a mini-trangia westwind to see if the commercial version performed any better. The only difference I noticed between the trangia and my best stove ( a basic pepsi can style with inner wall and fiberglass wicking) was that the trangia is a bit more fuel-efficient.
The answer is the altitude and temperature. (At least that's the conclusion that I and my outfitter came to.)
I live at 7,000 feet and tested outside in breezy 25 degree weather. I have a feeling that the stoves will perform much better at lower altitudes and higher temps, though I haven't had the chance to try that yet.
Also, the longest total burn time I can get with my homemade stove is about 8 minutes on that 3+ Tbs of fuel. The trangia does a little better at 9-10 minutes total; longer with the simmer ring.
So, how high are you? :p :D
Edited to add--the bigger your pot is, the more heat required to boil. I used a 16 oz capacity lightweight aluminum pot from my old boy scout mess kit.
Dooooood! I'm soooooo high! Well, not really. Actually, I'm probably at about 2000, maybe a little less. I NEEED my pot to get here. Wow, there's a lot of innuendo going on here...
I've used both Scouter/Cobra stoves and have been playing with double-wall pepsi-can stove designs. I like the former for the ease of building, but like the latter for the ease of priming.
I don't remember the exact numbers with the Cobra stove but I would typically get a rolling boil in 5 or 6 minutes with my 1L anodized aluminum pot (Primus Litech Trek kettle). Height above the stove makes a difference (~1 to 1.5in. seems to work well) as does using a windscreen. I generally use ~2T of fuel ancd acheive a full boil which keeps going for a minute or so. As I use a cozy for my pot, this is sufficient and I haven't been concerned with longer simmering/boiling times.
I think your biggest issue was using a 4qt kitchen pot. The walls of the pot will conduct and radiate heat, and IMHO there's just WAY too much pot there for boiling 1pt of water -- much of the heat will be lost due to the pot.
Hey--when your pot gets there, see if you can use it to bake!
alright, alright, I'm done.