Holy stove efficiency batman!!! Soto/Jetboil

[Luke Moffat]

Maybe this woudl best be in the MYOG gear section of this forum, but I didn't make a single bit of this setup, just modified stuff so I'm sure it not would qualify hence me posting it here.

So finally got around to getting my jetboil stove cut down and the notches cut in the bottom for the 3 pot supports of my new SOTO stove. The idea is that while the Jetboil stoves themselves are heavy compared to other canister stoves (they weight 7 oz) the jetboil fluxring I feel does make for improvments in boil times. So I figured why not combine an ultra-efficient canister stove (SOTO at 2.6 oz) with an efficient pot (jetboil pot).

Decided to have my jetboil pot cut down at work as we have unlimited metal working tools to work with after hours and a guy there loves to do little projects like that and made look much better than the frankenstien I no doubt would have created. Heck he put a like OEM bevel back on the pot after he cut it down so the original lid fits on there once again. The new jetboilette is only 4" deep vs. the standard jetboil pot being 5.75" deep.

Here is a pic of the two side by side of just the pot themselves:

Anyways now back at home I decided to do a few weight comparisons.

My naked jetboilette without/cozy/lid/or bottom cup comes to 4.4 oz. The orignal stripped the same way comes to 6.0 oz. The bottom cup weighs 1 oz even compared to the 1.3 oz lid. .3 oz isn't much so I'm sticking with the tighter fitting and more functional lid over using the bottom cup as a lid.

I also had my wife remove the handle and cut the cozy to fit my jetboilette.

So the total weight difference.

The jetboilette with 110 gram snowpeak fuel canister brand new, plus the soto stove, and the sippy lid comes to 15.6 oz.

The standard jetboil cup with the standard jetboil stove with the same fuel canister comes to 20.6 oz or a 5 oz weight savings overall.

Here is the two being weighed in. The new bevel actual holds the lid on a little tighter even than the original bevel.

Jetboilette all packed up:

Orginal packed up:

The Soto stove installed on a fuel canister is taller than a jetboil stove is but since the jetboilette is shorter the overall height of the smaller jetboil setup is slightly shorter. The notches cut out for the pot supports make the jetboil pot VERY secure (compared to your standard pot on these supports obviously not as secure as a jetboil locked into a jetboil stove). Though I still do have the option if desired to lock the original jetboil stove into the jetboilette.

Now for the disclaimer:

The follow tests were conducted by a person with absolutely ZERO scientific background and realizes that these test will more than likely be scrutinized heavily due to one or many factors that would render these tests of little to any actual real world meaning. :D

All tests were done at room temperature with 500 mL (the fill to line) room temperature water.

Room temperature fuel canisters boil times:

Jetboil with jetboil stove:

2 minutes 5 seconds.

Jetboilette with Soto stove:

1 minute 35 second.

Last night I put two full fuel canisters in my freezer that was set at -10F.

I quickly took the first out and screwed on the jetboil/jetboil setup and it boiled the 500 ML of water in 3:45 seconds.

After that I took the 2nd freezer canister and screwed it onto the SOTO stove and fired it up. It boiled the 500 mL of water in 1 minute and 50 seconds.

So the coldest canister did have some apparent affect on the SOTO's performance but not much from what I can tell. Where the jetboil/jetboil was nearly twice as long to get a boil and the flame was noticably smaller and quieter than the Soto with the cold fuel bottle where I couldn't notice or hear a difference between the room temp and the cold fuel bottle.

Overall I'm VERY happy with my findings so far as my new setup that is both 25% smaller and 25% lighter and boil times are twice as fast in colder climates. I think this could be one of the most fuel efficient canister stove combos out there right now.

[ben wood]

nice! i like the metal work. i have seen jetboil effeciency drop dramatically in colder weather as well, this is an awesome solution to the shortcomings of the jetboil system.

[John Vance]

Nice work! I have been kicking this idea around myself but lack the tools to make it look OEM. Please let us know how it works outdoors with a little wind. Adding a windscreen would reduce the advantages for me somewhat but the increased cold weather performance would be worth it.

I wonder how this would work with the 1.5L flux-ring pot for winter and snow melting. I wish someone made a Ti version of these.

[Alex Gilman]

I want one!

[Franco Darioli]

Tony Beasley did that some time ago, from memory for one of his stoves.
See also this thread :
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=7265&skip_to_post=85972#85972
Franco

[Roger Caffin]

Hi Luke

Well done!

Just for reference:
SnowPeak canisters contain a '15% Propane, 85% Iso Butane mixture'
Iso-butane boils around -12 C
-10 F is -23 C (that's well below the boiling point of isobutane)
Gas only comes out of the canister if the liquid is above boiling point

I suspect you were using new canisters? Because I think that the gas coming out of the canisters was almost entirely propane, at least at the start. What this means is that there may be not all that much propane left in those canisters, and using them in this sort of cold might result in no gas coming out by the time you have used about 1/3 of the canister.

Why the difference in performance time? It could be expected to be like this for any small upright stove, not just the SOTO. What happened is that when the stove started burning, heat was reflected back down to the canister and it started to warm the canister up, so the gas got warmer and continued to boil out of the canister. If you are *really* careful, you can do this in the snow, but it takes practice and skill.

Why was the Jetboil stove so much slower? Two reasons. The first is that the Jetboil stove is inherently slower, by design. Yes, by design. Jetboil asked Primus (who actually designed the stove) to make it 'underpowered'. The jet is rather smaller than on most.
The second reason really highlights the problem with the Jetboil design. The stove body blocks heat from being radiated back down onto the canister, so the canister does not get warmed up. Cold canister => low gas pressure => low gas flow => low heat.

Cheers

[Stuart R]

Hi Roger

> SnowPeak canisters contain a '15% Propane, 85% Iso Butane mixture'
> Iso-butane boils around -12 C
> -10 F is -23 C (that's well below the boiling point of isobutane)
> Gas only comes out of the canister if the liquid is above boiling point

Yes, but the *mixture* will boil at -21C, at least when the canister is new

Perhaps the freezer was not quite -10F. Also, canisters warm up pretty quickly in an ambient of 10-20C

> I think that the gas coming out of the canisters was almost entirely propane, at least at the start

37% propane coming out at the start. By the time the canister is 50% full the mixture will only be 4.3% propane and the boiling point will have risen to -15C

You can the same fun with the spreadsheet I sent you. Just change the eqn for the VP of n-butane to that of i-butane in cell U4
1.333*POWER(10, 6.74808-(882.8/(240+S4)))

[Brian Martin]

Sorry if this is straying off topic

Roger you state

'The second reason really highlights the problem with the Jetboil design. The stove body blocks heat from being radiated back down onto the canister, so the canister does not get warmed up. Cold canister => low gas pressure => low gas flow => low heat.'

So would removing some of the material from the bottom of the Jetboil mount, thus increasing the radiated heat to the canister, increase efficiency or just temp and boil times?
Is there any danger in increasing this feedback?

Thanks!

[Joe L]

@Brian

While using the modified stove, often touch the body of the canister. If it is not overly warm (very subjective) it is not in danger of exploding. Do canister stoves explode when left in car trunks in Phoenix in June? Not that I know of. Those temperatures are hot for bare hands on metal.

No manufacturer can accept the liability of telling you to monitor the canister temperature, but you can check its warmth. One of the UL tenets is using knowledge to allow comfortable camping with less weight. My suggestion is to monitor your current canister before the mods, then watch for a comparison level of warmth after the mods.

[Roger Caffin]

Hi Brian

Yes, you could remove some material from the Jetboil mount, but (from memory) that will not improve the view the canister has of the flame by very much.
Why bother? The Jetboil is still underpowered. Use a good upright instead.

As to the safety aspect (very correctly noted by OP), see our article on Exploding Canisters for more detailed info.

Cheers

[Brian Martin]

Joe, Roger – Thanks for the input and have great holiday.

[Paul McLaughlin]

Have you measured the amount of fuel used by each stove to boil the 500ml? I'd be curious to see whether the difference is just speed, or if there is a difference in fuel efficiency.

[Luke Moffat]

So was able to do a 40 mile backpack/packraft loop that last 3 days with my wife, sister, and bro-inlaw. We brought two 110 gram snowpeak fuel canisters as I didn't want to run out and there were four of us so the extra 6.7 ounces didn't make or break anything.

Anyways we had upwards of 20 500mL boils, didn't count exactly which I should have, but they were boiling while I was setting up the tent and whatnot. Anyways, we never had to swap to the other canister and there is still a fair amount (the canister now weighs 4.7 oz total so burned roughly 2 oz of fuel for 20+ boils) of fuel left in there for solo overnight ventures or just long day trips. We were camped at the mouth of the Ruth River (inside Denali National Park) on a river banks with 20+ mph winds and the little soto performed like a champ. Though the downwind side of the cozy did get singed a little but no worse for the wear overall. Still very impressed with the boil times of this setup.

Roger, I'll be sure to use up both those fuel canisters that may contain mostly iso-butane before the summer is out so no worries there so long as it stays above 20F. :D

Look forward to putting this setup to use in the coming months.

-Luke

[Stuart R]

> Anyways we had upwards of 20 500mL boils, didn't count exactly which I should have, but they were boiling while I was setting up the tent and whatnot. Anyways, we never had to swap to the other canister and there is still a fair amount (the canister now weighs 4.7 oz total so burned roughly 2 oz of fuel for 20+ boils)

Really?

Basic physics tells us that burning 2oz (60g) of gas releases 2.75MJ of heat. Even if the stove/pot combo was 100% efficient that would only boil 7.3 litres of water.

I think you have over estimated somewhat

[Martin Rye]

"Basic physics tells us that burning 2oz (60g) of gas releases 2.75MJ of heat. Even if the stove/pot combo was 100% efficient that would only boil 7.3 litres of water." – I wonder if you are wrong as the Jetboil site claims 12L of water boiled per 100g canister. The other person did 20 500ml boils. So he should have some gas left. Heat exchanger works. I recently started using a Jetboil and like it a lot. Sometimes a light stove is not always the best stove. I have used many gas stoves and the worst has been a Snow Peak stove – the best in the damp and the wind: Primus and also the Jetboil. I don't care what a lab test tells us. Out in the hills when it is damp and your tired is when you find if a stove can deliver- the Jetboil does it rather well I am finding. I also see many people give it 5 out 5 on this site. Maybe they to find it works rather well out of the lab and in the wilds.

[Roger Caffin]

Hi Martin

Your results are a little at odds with many other peoples' field experiences. But I could understand them if you were not using a good windshield. What were you using as a windshield?

Cheers

[Martin Rye]

Roger I don't get at odds? Lots folk rate the Jetboil on BPL. I recently as stated started using one and am delighted with it. Fast boil time, gas efficient and no windshield used so far. Luke used his (mod version) 20 times to boil 500ml on one canister. Very good results and inline with Jetboil claim of 12L water boiled per 100g canister. Mine is used to boil water and as a drinking pot. Takes no more space in my pack than any other pot/stove combo. Weight is acceptable for good performance and having tried several stoves over the years I am very pleased with it. One last point. On a recent trip I cooked out one night and inside my Duomid two. Other nights in the hills the stove was used outside at all times. Typical UK conditions. Bit damp, chilly. When nasty and windy I am in the DuoMid. In the field it has been a good stove.

[Rod Lawlor]

Martin,

I'm pretty sure Roger was talking about your experience with the SnowPeak, rather than the Jetboil. (He does love his Snowpeak!)

[Roger Caffin]

Hi Martin (and Rod)

Yes, I was talking about the Snow Peak GST100. Many of us find them excellent stoves even in bad weather, but we do use a full windshield with them. Much lighter than the JetBoil even over a week-long trip.

But, ymmv.

cheers
PS: I have walked the Pennine Way in 'variable' weather, and Offas Dyke in filthy weather.

[Stuart R]

> the Jetboil site claims 12L of water boiled per 100g canister

This is physically possible: if the water starts at 25C the stove/pot would need a thermal efficiency of 82%.
I have not made any measurements on the Jetboil, but 82% efficient is feasible (an ordinary stove/pot is typically 50-60%).

> The other person did 20 500ml boils

Boiling 10 litres of water using 60g fuel with 82% thermal efficiency would require that the water was starting at 45C – unlikely.

[Bob Gross]

I once knew a backpacker who stored a liter of water in a water bladder that wrapped around his waist, in contact with his skin. As a result, the water was prewarmed to almost body temperature before he put a kettle full on the stove.

That is not exactly cheating.

–B.G.–

[Martin Rye]

Sorry about getting back to you Roger. The stove was a Ti Gigapower stove. It was fuel efficient I suppose. Just annoyed me when a mate using my borrowed Pocket Rocket and same sized pot melted snow and was enjoying a brew on top of a Munro while I was waiting for mine to melt the snow, so begs the question which stove is most fuel efficient. The one still burning gas or the one that boiled the water and is turned of? In fact every break he had a brew faster and had turned of the gas on his stove before me. Then the thing use to flare up on occasions. Cleaned it and checked it over. I used it on two TGO Coast to Coast trips and it flared up on the last one and that was the end for me with it. So it got a fair try from me. Still it was a stove I just did not like and did not get on with. I know you like it and others. Not me.

[Luke Moffat]

Stuart,

Not sure if I overestimated or not. But we were out 2 nights for 4 people. Thats 4 boils per night for dehydrated meals for dinner (8 boils there). 4 cups of 500 mL water one morning and 8 cups of 500 mL water the 2nd morning as we just sat around and watch to sun come up over Mount McKinely.

If it makes a difference the canisters full are 7 ounces not 6.7 (those are the jetboils that are 6.7) so I burned 2.3 ounces. Not sure were the error came into effect, but you are right there is no way in heck this setup is 100% efficient. Like i said in my first post I have no scientific background and there are many factors that will render my findings of little real world use. :D Also I guess I can't count the coffees as full boils anyways though as I just get them hot not boiling so I don't have to wait for them to cool down to drink them right away. Didn't really think of that until I just read your post, but that could contribute as well. Didn't intentionally mean to mislead anyone, as its not a magic setup by any means.

Thanks for causing me to think (scary I know :D )

[Gary Dunckel]

Roger, I'm also a fan of the SP giga stove. My 4 year old stove seems to be gunking up a bit and it sometimes sputters, and I'm wondering how I can clean the jets/burner. I have the same issue with an older JetBoil burner. Can I just soak them in alcohol or something, or is there a better way to de-gunk them?

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