Running on Zero Nitro - RC Groups
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Jan 09, 2018, 09:07 AM
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Running on Zero Nitro


What would a guy need to do to run zero nitro? I'm getting back into glow engines and since hobby shops rarely have much as far as glow fuel anymore I'm entertaining the idea of running FAI fuel. I have never run an engine of any size on zero nitro so I have no idea how a modern engine would run on it. I know many older engines were designed to run FAI. I'm sure I can find methanol without too much trouble and the oil is easily obtainable (I live in the Milwaukee area) but the nitro might be more difficult and also add to the cost.



Mike
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Jan 09, 2018, 09:18 AM
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I TOBOR's Avatar
They run fine on it, no engine actually needs nitro methane. Guys in other countries do it all the time and some here too. Some say that the needle settings are narrower, and that may be true but the sweet spot is still the sweet spot.
Jan 09, 2018, 09:29 AM
Simply Reliable
Gary Cee's Avatar
Varies by engine.

Sometimes an increase in the compression ratio helps when removing nitro from the fuel.
Many engines however have been designed for zero nitro and they can be disagreeable when nitro is used.
Jan 09, 2018, 09:32 AM
Registered User
Thanks for the reply. I guess one thing I'm wondering is how much power loss would one get without the nitro. I've run a lot of nitro laced glow fuel through my model engines over the years, been running them since the mid sixties. It's always been my take that low amounts of nitro, say 10%, don't add a lot. I'm building a Great Planes Super Sportster 40 that I had planned on using a brand new K&B 40 on but I wonder if it would power the airplane decently on zero nitro. And how does a modern Schneurle engine like the other 40 I currently have, a Super Tiger 40, run on zero nitro?


Mike
Jan 09, 2018, 09:36 AM
Registered User
Slightly higher compression and a hotter plug than with nitro. Maybe just removing a head shim, or finding a thinner one. Some guys, and maybe one girl, add 2% acetone for better acceleration/midrange. Less flameouts. I have used it years ago on FAI speed planes, and there was no idle needed there, but I am sure that would be a bit fiddly until set up right. Really, if you have 5% fuel, and 0%, I doubt you would even notice. Wow, two repies in the time it takes me to type.
Jan 09, 2018, 09:44 AM
the great Gassifďer
I found some engines extremely tricky to dial in on low Nitro fuel (or rather, it took multiple runhours of small tweaks), but once set, running OK.
Jan 09, 2018, 09:55 AM
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KMatch's Avatar
Years ago I owned both the 40 and 60 sized Super Sportsters with their intended engine sizes. Likely Magnums or similar. They flew fine for buzzing around and aerobatics but I was never happy with vertical performance even with 10-15 percent fuels. If that's your goal and you want to go FAI, you might consider losing more vertical performance, going up an engine size, or ??.

And as others have pointed out, overseas nitro was either hard to come by or banned altogether depending on locations so one thing they did to counter this somewhat was to raise compression and add heat with a hotter plug. Expect a bit harder starts, trickier tuning, and less reliable and rougher idle with FAI fuel as compared to 15% but not enough so to change your mind, just "different".
Jan 09, 2018, 10:13 AM
Suspended Account
You ST engine that is set up to run low nitro will run better on FAI fuel then the K&B that is set up to run 10% to 15% nitro. The Super Sportsters tend to build a little heavy so you may want to keep that in mind and look for some mods that will shave some weight.
Jan 09, 2018, 02:03 PM
Registered User
i fly most of my fleet on 5% for cost reasons and one advantage is the longer run time of the engine.
On my os engines i the head gasket is been removed to increase compression,
Jan 09, 2018, 02:40 PM
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burlesontom's Avatar
I used to buy all my RC stuff from Johnny Cashburn and he sold 10% fuel and also gallon cans of what he called "Sport" fuel with 3% nitro. The 10% was $10 a gallon and the 3% was $6 a gallon. (1980) He told us we would never know the difference and he was right. I have never ran 0% so can't help there. All our engines were just over the counter OS and Fox engines.
Jan 09, 2018, 02:45 PM
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AA5BY's Avatar
I ran home mixed FAI fuel exclusively for the first ten years in the hobby from '74-84 except half A engines. IIR, tuning then was different in that an engine was more often tuned for optimum vertical flight... holding the nose up and sensing no sag. Often that resulted in four stroking on the flats. However, that could have been due to lack of muffler pressure during some of those years.

Yeah... FAI fuel should work in many engines.
Jan 09, 2018, 04:56 PM
Engine Frankensteiner™
1QwkSport2.5r's Avatar
I use true FAI fuel to break in new engines and for everyday running of certain engines. Some engines pickup 500rpm on 5% Nitro from FAI, but after that, usually you’ll only see about a 200rpm gain for every 5% Nitro you add for most engines. Removing a head shim helps idling and transition issues, but 3% acetone could be added to help with this as well.
Jan 09, 2018, 05:57 PM
Registered User
I have tried 0% nitro and didn’t like the way some of my 4 stroke engines would idle. The mix I settled on is 3% nitro with ˝% acetone. I now get a very good idle. This mix runs good in all of my engines both 2 and 4 stroke. I’m sure that my WOT is a bit less than the guys running 15% nitro but I don’t care because I am just a sport flyer. My fuel mix is low cost and I run a lot of fuel over the long Texas flying season because I live at my own private flying field out in the boonies. Also, I would have to drive hours to buy commercial fuel and it is much easier and cost less to mix my own. The methanol is available about 30 minutes away from me and ordering a gallon of nitro online is easy and last a long time with using only 3%.
Jan 09, 2018, 06:05 PM
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KMatch's Avatar
How about a simple compromise? It's well known zero nitro isn't as desireable and only adding a small amount makes quite a difference. Why not create a simple formula to make a batch of FAI and mix in just enought store bought high nitro content to bump it to around 5%? Sounds complicated at first glance but let it sink in a moment. Buy a gallon of 20% or so store bought and with proper blending you can have several gallons of 5% much cheaper than store bought.

Or the post above me I didn't see works well too!
Jan 09, 2018, 07:21 PM
Registered User
I'm into the big Super Tigres, and run them all on 0% nitro fuel that I mix myself. These engines were made for this fuel, and run great on it! I make 88/12 for the 2000-3250 engines, and 82/18 for the 2300, and even in a .60 bluehead.


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