Feb 12, 2011 at 1:07 am #1269056
I spent the evening cleaning 3oz cat food cans and punching holes. I followed the directions found at ttp://jwbasecamp.com/Articles/SuperCat/index.html. I had to use about 50ml fuel (near overflowing) and it took 9 minutes to boil 500ml water in a SnowPeak 700 and that was indoors on my stove and a windscreen.
Pretty ho-hum performance with that setup. I tried a SnowPeak Ti bowl, which is 1-3/8" wider than the 700 and that seemed to work better, although I fizzled out on watching pots boil and didn't get a thorough test.
I have another ti pot that is an orphan from a set and that is 4-7/8" wide and 2-1/4" deep. 2 cups of water fill it to just below the brim and I got a 6 minute boil with that. I can live with that, as I was looking for a SUL overnight and day hiking rig to make a little hot water for coffee/tea/oatmeal kinds of things. I'm leaning more to an Esbit wing stove instead.
I don't have a cat, so my dogs were delighted with my testing and the left-over cat food. I think they are developing a Pavlovian response to the smell of denatured alcohol :)Feb 12, 2011 at 3:53 am #1695723
My current setup is a 700ml pot from backcountry.com and a Supercat.
If you're going to be boiling 500ml or more I'd guess you're doing more than boil-in-a-bag meals. For those I'm only boiling about 1 cup.
If it's for a big cup of coffee there's no need to get it to a full boil. And that's the only time I deal with heating that much water when backpacking.
If I pick a spot that's pretty sheltered from the wind and use a windscreen even 91% rubbing alcohol performs well for these tasks. I've never timed it but I'm sure denatured alcohol is faster and might use less fuel to accomplish the same tasks.Feb 12, 2011 at 5:51 am #1695731
@sschloss1Locale: New England
I have a supercat that I use with an Evernew 1300 ml pot and a BPL titanium windscreen (which wraps fairly tightly around the pot). I can usually get a rolling boil in 6 minutes or so. Maybe wider pots are better for this stove.Feb 12, 2011 at 6:28 am #1695739
Gary L. ThompsonParticipant
I have experimented some with various alcohol stoves and find that the conventional wisdom that low pressure jet stoves are more efficient but don't burn nearly as hot as chimmney type open flame stoves to be true.
With Robinson's Cat Food Can Stove (link on Zenstoves.net) I can boil 24oz of 40 degree (F) water in less than 5 minutes in cold but calm conditions. However,it will use more fuel than a pressurized stove. I didn't really like the side jet stoves b/c they are much tougher to get going properly in cold conditions and they are kind of a shaky setup with the pot resting directly on a small stove. The do IMHO need a fairly wide pot to work well. However, some people love their side jet stoves; perhaps they know more than I do about how to make and operate them.
Alsohol stoves are more sensitive to wind and need a good windscreen. With an open flame chimmney stove you need a reasonable distance from the top of the stove to the bottom of the pan. Robinson's setup has slightly over an inch and he says that more is better. I have found this to be true. I haven't found the sweet spot but can say that 2 or 3 inches is clearly better than one inch. He set up for one inch so the entire setup would fit into his pot. I use a 5 inch diameter coffee can as a windscreen cut to a height of 4 inches with hardware cloth over the top of the can for the pot to sit on. My pot is a 4&1/2 inch diameter Titan pot and this provides a decent gap between the pot and coffee can. While I can boil 24oz (or even a quart) with this setup (with bigger pot), it really gets to cooking with the stove enclosed in the can and can burn so hot that I think its really getting inefficent. Sticking to a 16oz boil is probably better. You have more control and fuel useage is easier to predict.
Zenstoves.net has a ton of good info and links. Warning, experimenting with these stoves can be addictive.
GaryFeb 12, 2011 at 6:50 am #1695744
I've never been that impressed by any of the feline stoves. Their performance is darn good in comparison to their simplicity though.
I've mostly settled on the Penny Stove for when I need an alcohol stove.
http://www.jureystudio.com/pennystove/Feb 12, 2011 at 8:13 am #1695762
I aimed at 500ml/2cups, which is useful for most of my cooking. 1 cup is much easier. Wider pots are much better. The SnowPeak bowl is 5-1/4" diameter at the top, where the 700 is 4".
I did make one from a Vienna Sausage can, which is the same diameter as the cat food cans and nearly twice as tall, so it can hold a lot of fuel, but there are issues with warm up and . The physics of this design is tricky— using a steel can doesn't work as well, etc.
My aim was to make a quick and dirty stove for a hot drink, and as others mentioned, you don't need a full boil for that.
I did try it with a Ti Sierra Cup and that was okay. The flare on the sides of the cup was an interesting mix with the flame pattern.
I'm thinking the White Box side jet rig is better suited to what I want. Esbit will work too, especially for occasional use, with the usual smell/soot/cost factors.Feb 12, 2011 at 8:47 am #1695781
@rosierabbitLocale: Pacific Northwest
Dale – what kind of fuel are you using? Is your denatured alcohol really old? I've heard the quality can vary from can to can and age. I use the yellow HEET fuel and get better results. To keep your dogs happy, you could try making a few more stoves with holes spaced farther apart to see if that helps. I've been very happy with my supercat.
Edited to say I use a 3C AGG pot.Feb 12, 2011 at 9:13 am #1695794
Gary L. ThompsonParticipant
Dale, I think BPL did a review on the White Box Stove and said it was best suited for wide pots. You might check the review. Also, re fuel, BPL did an article on fuel and ran tests on various types of fuel. I burn dna that is mainly ethanol, 85%+. Heet is mainly methanol. Methanol is easier to light, boils at lower temp and may give slightly better results than ethanol b/c of this. But, ethanol has a higher energy content per ounce. The question is can the stove extract this higher energy content. There may be some health risks with methanol; I'm not qualified to judge on this but elect to be safe and use ethanol.
GaryFeb 12, 2011 at 10:39 am #1695828
@ghgeigerLocale: Appalachian Trail
You might want to consider a stove with upward pointing flames. I plan on taking a homemade Fancee Feast stove with me on my upcoming AT hike in conjunction with a heiny pot. I just ran a quick test with a similar sized pot to yours to see what kind of boil times i'm getting. Here's the results:
Stove: Fancee Feast
Pot: Coleman Aluminum pot with lid, 3.85" diameter
Water Temp: 2 cups – 46 degrees Fahrenheit
Fuel: DNA "green can", mostly ethanol
Conditions: Indoor, 70 degrees Fahrenheit
Time to full bloom: 26 seconds
Time to full boil: 6 minutes, 44 seconds from initial light
Fuel Consumption: .58 oz or 17 ml
While the Fancee feast is not quite as simple as the super cat, it is by no means difficult to build–much simpler than a pepsi can stove. The hardest part is acquiring the center pot stand part. I found mine at the local big box hardware store, it is the outer metal surround from a flexible PVC coupling. Here's the thread that I got the instructions from to build the stove: http://www.whiteblaze.net/forum/showthread.php?t=27262Feb 12, 2011 at 1:01 pm #1695884
The Fancee Feast is pretty simple, provided you have the screen. Something to work on.Feb 12, 2011 at 1:17 pm #1695891
@jumpbackjackLocale: Armpit of California
Me and my friend Kevin, have built a few cat stoves with different patterns, the basic pattern works fine for us. I can boil 2 cups of H2O in the house with no wind screen in about 6 min. Outside with a windscreen it takes around 7 1/2-8 min. with a burn out time of 11 min. I use Yellow Heet and 2 oz of fuel, we also are using the aluminum Imusa mug, no lid. I also tried it with my GSI Minimulist pot with lid and it took 1 min. more to boil, these are rolling boils. I made one with 1/8 holes that I really like, but without a windscreen the wind will blow it out. I put my holes as close to the top as possible, so I get a narrow flame pattern around the mug, seems to work pretty good, I haven't had a chance to use it in the field yet, hopefully in 2 weeks I will.Feb 14, 2011 at 11:02 am #1696548
> I had to use about 50ml fuel (near overflowing) and it took 9 minutes to boil 500ml water in a SnowPeak 700 and that was indoors on my stove and a windscreen.
50ml of fuel to boil 500ml of water seems way, way too high. I don't use a Cat stove, but I've found that there's little difference between the efficiency of the various alcohol burners, from simple open cups to jetted burners. 15ml of 95/5 ethanol/methanol fuel usually boils 500ml of water at moderate room temperature.
My suspicion is that the flame ring may be too big for the pot you're using (the SnowPeak 700), and the heat is simply passing uselessly up the side. Simple test: can you leave your hand at the edge of the pan (without burning…)?
I generally use a variant of the classic 'Pepsi Stove', built from a 250ml Red Bull can, with an inward-pointing jet ring. This produces a conical flame which is a better match for small pots. It does require a pan support to maintain a flame gap between burner and pan.Feb 14, 2011 at 7:34 pm #1696784
I agree– there is a lot of waste due to the flame pattern/pot diameter. I need a simple design for a small pot.Feb 17, 2011 at 9:00 pm #1698145
I have made several non-pressurized stoves from potted meat cans and the like. And have a pepsi can stove too. I finally made one from a bud light aluminum beer bottle, and that's now my stove of choice. It blossoms really fast and boils 2 cups of water in less than 5 minutes with very little fuel (I use HEET). I used wooden arrow's instructions on youtube and it works great. I've made several now and given them away. I'm amazed how well they work.
Half the fun is making all these little stoves.
MikeJun 23, 2011 at 9:16 pm #1752734
I've been having similar trouble with my recently built Super Cat stove.
Followed the crazy simple construction directions so I don't think design is at fault, but what else?
I'm using a .85L MSR Titan Kettle, I've tried with and without a good aluminum windscreen, on the stove in my kitchen with the exhaust fan on.
My S-L-X denatured alcohol is fine, but I guess I could try some "new" stuff.
I can post some photos of the set-up later but it's pretty standard.
Also, I'm getting boiling times of close to 10 minutes, with a full 1 oz of fuel, nothing left over after 13-15 minutes.
Any ideas?Jun 24, 2011 at 5:40 am #1752793
I've never taken more than 2/3 oz to boil 2 cups. Usually it's <= 1/2 oz.
Are you certain you got Al vs steel cat cans?
Wider pots do work better and Al pots work better, though I note Skurka used an Evernew Ti 0.9L with his for AYE. I have used both an AL "mess kit" pot (~5.5" dia X 2.5" tall) and a 24 oz Heineken keg can on mine. The latter only works well because the Al is so thin that heat transfer is about the best it can be.
Are you using a lid?
I found that having a ~1/2" gap on the windscreen during my tests was too small with the Heineken pot at least. I could always boil faster without the screen (yes, it did have some air intake on the bottom edge). I had to leave at least an inch gap to get close to the same performance.Jun 24, 2011 at 6:35 am #1752799
Tyler, could you clarify how much water you're boiling?Jun 24, 2011 at 11:37 am #1752904
I'm definitely using Al for the stove. Pot is Ti, could try with my Fosters pot but haven't yet.
2 cups of water for the above figures.Jun 24, 2011 at 3:06 pm #1752974
Do you think more vent holes in your windscreen would increase efficiency, or is there something important about having a gap between the top edge of the screen and the pot (perhaps it channels air through the system in a better way)?Jun 24, 2011 at 3:19 pm #1752977
All of this air flow stuff is quite important for efficiency. First, you have to have enough intake air vents at the bottom. Then the flame makes the heat, which rises. If you have proper air flow going out the top, it will allow most of the heat to be absorbed by the cook pot, yet the flow does exit with proper force.
Some stoves like a Ti-Tri Caldera (in alcohol mode) have no air gap at all around the top of the pot, and the air exit is a modest number of small holes in the windscreen. Other stoves leave a half-inch air gap around the top of the pot.
You have a half-dozen variables all fluttering away, and they each have to be balanced against the others. You do it one way, and you will get a faster boil and too much fuel usage. You do it another way, and it never boils very good.
One thing you might want to do is to insulate the stove fuel bowl from the cold ground. It doesn't need to be much more than one or two thicknesses of aluminum foil or plastic. However, that allows the fuel to reach a hotter temperature, and that may be helpful.
–B.G.–Jun 24, 2011 at 6:55 pm #1753054
@pda123Locale: Eastern Mass
Aluminium cat stove, two rows of holes, DNA fuel, 5" diameter light Aluminium pot with lid. 2 cups of tap water, ambient temp ca. 70. Full rolling boil in 4 min 40 seconds. Total burn 11 min 18 sec.
The flames just reach the edge of the pot and do NOT lick up the sides. I believe this is the determining feature which gives the fast boil time, together with the extremely light weight of the pot.Jun 24, 2011 at 7:04 pm #1753058
Paul, your flame pattern looks good and normal, so it gets good results with that wide pot. Now, if somebody put a gun to your head and forced you to make a similar stove to work with a small diameter cook pot, what would you do differently? Let's say about 3.5 inches in diameter. I don't know that there is any easy solution.
–B.G.–Jun 24, 2011 at 7:24 pm #1753069
@pda123Locale: Eastern Mass
When I have an approx. 1 1/2 oz 32 fluid oz. pot which cost me US$ 1.99 at a thrift store, why would I want to change it?Jun 24, 2011 at 7:28 pm #1753072
I didn't say that you needed to change your cook pot. In fact, I have an identical one. However, many readers here may have a narrow cook pot, and a standard Super Cat may not be very efficient. I'm just wondering if the standard Super Cat can be adapted for narrow pots.
–B.G.–Jun 24, 2011 at 9:16 pm #1753101
> Do you think more vent holes in your windscreen would increase efficiency, or is there something important about having a gap between the top edge of the screen and the pot (perhaps it channels air through the system in a better way)?
I don't know. On the wide short pot, it doesn't matter what the gap is it seems and I have maybe 8-10 holes punched in the bottom on one side of my short windscreen (~2.5" tall). For my Heine pot, I used my Windpro windscreen, which maybe is 5" tall and it has a large gap in the bottom for the fuel line to pass through. I also made another with one large hole like Jim Woods' SuperCat site shows but without the little tunnel. It should get more than enough oxygen. I gave up after a few hours of testing (ran out of time before my trip). Without the screen, it would boil in 7 min. With the screen and a small gap, it would take several minutes longer and often didn't reach a boil. Large gap was a couple minutes longer and sometimes didn't boil. Worked fine at altitude and cold water but I don't recall if I ever had to do 2 cups or not as most of my meals are 1-1.5.
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