Alcohol Stove Math

This is probably silly, but what about using E85 or E95 in an alcohol stove? Would the 15% (or 5%) that is gasoline render this fuel dangereous to use? Or would it perform like ethanol?

If it is dangerous because of the gasoline, is there a way to remove the gasoline? Perhaps the gasoline is more volatile and thus would evaporate off quickly if you left it un-capped. Environmentally, that's not such a great idea but I'd be interested in knowing if it would work.

Might blow yourself up.
Gasoline is way too volatile.

Can you get 93% isopropol alcohol ?? IT burns hot, but its dirty.

> Can you get 93% isopropol alcohol ?? IT burns hot, but its dirty.

And the fumes during burning are toxic. Gave co-author Tony Beasley a very bad hangover.

Cheers

> what about using E85 or E95 in an alcohol stove
I doubt that E95 would be very different from some forms of denatured ethanol.
E85? Dunno – depend a bit on what's in it. Does it contain benzene (autogas usually does)? Be aware that benzene is a known carcinogen. Other additives?

Cheers

De-natured alcohol math.

.07 liters of fuel per person per day.

What was the starting volume you used for the Featherfire test? It actually makes a difference to the fuel efficiency. Also, did you recover unused alcohol by using the snuffer cap, or just guesstimate the fule neeeded? I find the best fuel efficiency is starting at at least 25ml fuel, then snuffing the flame and recovering the unused portion.

There's also another way to increase the fuel efficiency (and speed) of the Featherfire that you can't (as in shouldn't) do with a Pocket Rocket…use a Caldera Cone for the windscreen. This also makes the Featherfire more stable and wind-worthy. Although the pot will sit a little above the top of the cone, it still increases fuel efficiency.

Just the stove weighs 42g and I weighed the stove + fuel at about 80g, so I had about 40g or nearly 2 ounces of fuel in there (I think a fluid oz of methanol weighs 22g).

After the stove was out, I extinguished it with the snuffer and then weighed the stove with the fuel still in it, and the difference was my fuel used. I did recover the unused fuel using the vacuum sucker cap thing that PackaFeather sells.

I am going to try to make a caldera cone for this. I'm working an insane amount right now (ie. 54 hours of the last 70) but Tuesday I'll have time to try some stuff. I'll make a Caldera Cone (there's a great YouTube vid).

I learned that the highest alcohol they can sell here in BC is 151 proof (75%) which wouldn't be any more weight efficient than methanol. I can get 191 proof alcohol in Alberta but that's a 10 hour drive away. I'm better off to go to the states. Alcohol is really expensive in Canada too. A 20oz of 151 Rum is $35….not really worth it. I'd love to get some denatured ethanol, but that might have to wait a few months until I visit the USA.

The testing is on hold for a bit because I'm waiting for my new 1.3L Evernew Ti pot to arrive. I don't want to spend hours making all sorts of windscreens and a caldera cone for my current pot which likely won't be seeing trail time anymore.

I couldn't resist playing with the FeatherFire…it's such a neat stove. I boiled 2 more pints tonight. I wanted to see how my stove would fare without a windscreen in dead calm weather, so I boiled these pints inside on my kitchen table.

The first pint I boiled at about 1/3 power. I didn't measure the time but it took a while….probably 12-13 minutes I'd guess. That used 17.4g of methanol which is the same amount as I used outside with a windscreen, but at 2/3 throttle. That pint outside took about 7.5 minutes. Now I wonder how this stove would do at 1/3 throttle with a windscreen…hmm

The second test was a repeat of the first test but at full throttle. That was way faster but used 20.2g of fuel which is 2.2g more fuel than the same test took with a windscreen.

My new Evernew 1.3L Non-Stick Ti pot arrived today so I spent about 3 hours making a caldera cone for it. The results were disappointing.

With the new cone, I boiled a pint indoors on my stove top. It took about 8 minutes and guzzled 19.6g of fuel. That's my second worst test yet, with the worst being no windscreen, indoors and the stove on max.

I repeated the test using my traditional windscreen instead, and the results were way better. That 2nd pint boiled in a 6 minutes and used 16.6g of fuel…..3g less.

Obviously there is a problem with the cone. I suspect the stove isn't getting enough oxygen. Next I'm going to try to improve the breathing of the cone by adding some more ventilation holes to it. I'm not that optimistic though. The cone weighs 75g (2.6oz) and my windscreen weighs 52g (1.9oz). Both are made from roofing flashing.

I suspect at the end of this testing the winning combination is going to be an oven liner windscreen weighing about 15g (0.6oz). Even working well, I'm skeptical that the caldera cone can save enough fuel to overcome a 60g (2.1oz) disadvantage in a reasonable amount of time.

I think a light oven foil reflector disc (4g or 0.2oz) will also prove valuable and be worth the weight. A FeatherFire, oven liner windscreen and reflector disc should weigh 65g (2.3oz) combined.

Compared to my Pocket Rocket (which uses about 7g to boil a pint at full speed), I can start with a 130g headstart because my stove, windscreen, relector is 20g lighter than a pocket rocket and my fuel bottle is 110g lighter than a 8oz canister.

This means I would be ahead for about 13 pints if my alcohol stove uses an extra 10g per pint. I think I can reduce this penalty down to about 6g per pint extra fuel by using ethanol and the reflector disc. This means the alcohol stove would be lighter for the first 22 pints (130/6 = 21.7) which is the bulk of trips.

I made some more modifications to my imitation Caldera Cone. By improving the ventilation, I was able to boil a pint on 17.6g of methanol vs. 19.6g before. That's a nice drop but it's still no better than what I'm doing with a good old windscreen. I boiled 2 pints using my windscreen with an average of 17.1g.

I think I'm ready to give up on the cone. I made a new windscreen from an oven liner today that weighs 17g vs. 70g for the cone. I just can't see the cone making back 53g over the course of a normal trip. It would have to perform about 2g better per pint just to break even and right now I can't even get it to match the performance of my windscreen.

I boiled a pint just now at 1/2 throttle with my oven liner windscreen (17g) and a reflector plate (2g) at about 60% throttle using 16.1g of methanol. That's a new record!

If I could procure some ethanol which is 20-30% more efficient I'd be looking at 11-12g per pint. That's really where I want to be.

My fuel bottle is 102g lighter than an empty 8oz canister and my alcohol stove setup is 23g lighter than the Pocket Rocket. That means I have a 125g weight advantage before I consider the weight of fuel.

The Pocket Rocket averages about 6.5g/pint which is about 5g less that what I hope to accomplish with ethanol. That means it would take 25 pints (125g / 5g) before the Pocket Rocket breaks even with its superior fuel economy. That's pretty compelling since rarely would I be on a trip longer than 25 pints.

Another avenue to explore is how the Pocket Rocket is affected by wind. I suspect the fuel economy would be affected more than my alcohol stove since I don't have a windscreen for the PR. Accordingly, real world conditions may favor the alcohol argument.

A second avenue is how effecient these stoves are for larger quantities of water. In my limited testing, the PR took about 80% more fuel to boil 2 pints, whereas the alcohol stove only took about 50% more. I've only a done a few tests so this may be an anomaly, but if this is the case then that strongly favors the alcohol stove when I camp with my wife since we usually boil more than a pint.