Glow Engines Discuss RC glow engines

Why I'm going back to glow

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Old 08-23-2015, 05:47 PM
  #1
psgugrad
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Default Why I'm going back to glow

About 4 years ago, I got hot for a gasser and bought a DLE 20 for my Four Star 120. It was for the usual reasons like being cheaper to run, less slop on the plane and you can put the fuel tank on the CG. Plus, it ran better than most of my glow engines.

Then, about 2 years ago I started researching mixing my own glow fuel and discovered a few interesting things. First and foremost, there is no need to be paying $20+/gallon for glow fuel at the hobby shop. I found a place near me where I can buy Methanol for $4/gallon. There were other places not near me selling it for considerably less. Then, I found a place where I can get (real) castor for $27/gallon delivered. Finally, I read where glow engines don't really need any nitro and that if you're using real castor oil, 12% oil is plenty and that larger engines can even go as low as 10% oil content if real castor oil is used

I mixed up a gallon of my own and I was shocked at how much better my engines ran. First, they started easier and didn't load up when idling. Transition was much better and, despite the lack of nitro, the engines made the same or even a little more power. Also, there was less slop on the plane. Icing on the cake is that the mix is under $7/gallon

I think the reason for the better performance was the fact that I was using less oil. The thinner fuel seemed to eliminate issues of loading up, transition, or fuel starvation with the nose pointed up. The difference was even more pronounced in cooler weather. I had always thought that glow engines needed 18-20% oil to be protected, but the reason the manufacturers specify this is because they have no idea what type of oil you're going to be using and real castor has far higher film strength than synthetics. The weak link in a glow engine, lubrication-wise, is the bottom of the connecting rod and 12% real castor is plenty to protect the bottom of the connecting rod. One of my engines, an ASP .46 has a lot of time now on this thinner, 0%-nitro blend and has never run better. There have also been no issues with the engine gumming up or getting coated with brown varnish.

When switching to this 0% fuel the only thing I changed was to a hotter plug. I also found that fuel consumption went down by about 15% since I'm not just sucking down a bunch of nitro plus a huge amount of oil that isn't adding any power...just making a mess of my plane.

I'd be curious to hear from other flyers from around the world who mix their own fuel and listen to their two cents worth.

PS: I almost forgot, no gasser has that wonderful smell of burning castor! (plus my basement no longer stinks)
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Old 08-23-2015, 06:43 PM
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I use nitro, all castor oil, and my engines run fine too. If the needle is set properly, I rarely encounter any tractability issues unless a glow plug is crapping out or the fuel tank insulation is falling apart.
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Old 08-23-2015, 07:43 PM
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Agree with both of you. I run fuel I modify from a store bought base. My basic mix is 7% nitro and 20% all castor fuel. I run old Enya engines with lapped pistons and sleeves. They run very well on this mix.

$27 a gallon for castor is a very good price, can you share the vendor with us? I need a gallon right now!
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Old 08-23-2015, 08:18 PM
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I paid $25/gal plus shipping for castor oil from SPLUBE.com (S&W fuels) for anyone interested. They were good guys to work with.
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Old 08-23-2015, 08:46 PM
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In the early RC helicopter years when Ernie Huber represented Kavan Helicopters he did a lot of Hollywood movie work (notably The Towering Inferno), he ran Super Tigre .61 ABC engines. Since the movie shots could not show exhaust smoke Super Tigre said he should run 100% methanol and 6% castor. I watched, and talked, with Ernie at a heli demonstration flying one of the movie helis on a hot Central California day. It was flown hard yet never missed a beat and absolutely no exhaust smoke.

I used ST engines in at the time (still do). A local fellow mixed fuel on a custom basis so he blended methanol/10% castor for me. Worked beautifully in both helis and airplanes. Very little residue to clean up.

Some commercial model fuel suppliers still make a Super "T" blend which is primarily for the large Tigres. I believe the blend is 100% Methanol/12% Castor/synthetic.

Your success with the glow fuel is based on proven blends. And is about as cheap as mixing gas/oil.
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Old 08-24-2015, 03:17 AM
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1qwk:

Thanks for the info. I checked the sight, looks like castor went up to $30 per gallon, still a bit cheaper than most other sources. I'll give them a try.

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Old 08-24-2015, 03:27 AM
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I called them to get the price I listed - they didn't have a gallon price listed on the site. Try calling them and mention the $25 price and see if they'll give it to you?

On the main subject about oil type/quantity.. My $.02 worth here is this... Castor oil is not going to save you in a lean run necessarily, and when running 12% oil content, your buffer zone for lean/safe is about as narrow as you can be especially using no nitro. If you use nitro, the needle setting automatically is/needs to be richer so there is more fuel volume going through the engine thus more oil going through. If you used 10% nitro and 10% oil, that would flow as much oil as roughly 0% nitro 12% oil which would run clean and not make much mess plus allow the engine to run a little cooler. My values are appoximate; YMMV.

I run 11% castor oil in my RC car fuel - I've run as low as 8% and as high as 18%. I settled on 11% as it runs clean and with using 25-30% nitro, there's a LOT of oil going through the engine at high RPM. The crankcase was left dry as a bone on 8% oil whereas 11% or more left some oil in the crankcase to protect he internals. I like using more oil to give a bigger safety margin. 20% in aero, 11-12% in cars.
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Old 08-24-2015, 08:28 AM
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A gallon of caster oil now that's one heck of a lot of laxitive
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Old 08-24-2015, 09:00 AM
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The website price list for S&W / SP Lube is not dependable. Call them for prices and ask for Stan. He is a nice guy. He came to one of our club meetings several years ago an gave a really interesting presentation on glow fuel.

The thought of a gallon of castor as a laxative is terrifying. Although not as bad as a 2 lb bag of diet gummy bears. http://www.amazon.com/Haribo-Sugar-F...ews/B008JELLCA

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Old 08-24-2015, 03:34 PM
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pspugrad : what is a gallon of glow fuel made of, in other words whats your recipe?
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Old 08-24-2015, 03:41 PM
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Sounds great, I for sure will be looking into mixing my own!
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Old 08-24-2015, 04:19 PM
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Couldn't be simpler: 88% Methanol and 12% real castor oil. I don't add any nitro, just a hotter plug, My favorite is the McCoy #59 (hot). Remember that nitro is virtually impossible to get in (most) countries outside the USA so it's not necessary...we're practically the only ones using it. It makes the engine a little easier to tune as the engine becomes a little less sensitive to needle settings. PS: I'm talking about engines .25 and bigger. When you get into the smaller engines like .15 and smaller then they can become a bit more difficult to tune with 0% nitro fuel. On the other hand, bigger engines (.60+) don't seem to notice the lack of nitro at all.

Last edited by psgugrad; 08-24-2015 at 04:22 PM.
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Old 08-24-2015, 05:59 PM
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psgugrad- are you buying your methanol locally? I'm north of the city.
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Old 08-24-2015, 07:01 PM
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Great discussion. Can you guys answer a few questions?

I know there's a difference between percentages by weight and percentages by volume. How do you guys do your mixing? Can you explain if you measure by weight or by volume and how you make those measurements?

Also, is there a difference in "quality" of the ingredients, depending on the manufacturer/source?

Tom
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Old 08-24-2015, 08:12 PM
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I mix by volume using weight. Most manufacturers mix by volume though.

I take whatever volume I want of part A, convert to a weight measurement and use a scale. Add part A until scale measures desired weight and zero scale. Add part B, and repeat. I feel this is a lot easier than measuring in a graduated container and transferring to a third container.

As far as chemical quality goes, I use what I know works and has worked in the past. Same goes for diesel.
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Old 08-25-2015, 01:07 AM
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Hi TJK,

Quick Sport's method is the best if you've got the equipment and the math skills.

Historically most home brewers mix by volume though. In the days before cheap accurate electronic scales there was no choice really.

I'd have to disagree with Quick on the large manufacturers though. Mixing by weight is a better industrial process, you don't have to worry about the temperature of your components or of the final product. You get a consistent product from one day to the next.

Quick is right though, you have to adjust the percentages of each component according to its specific gravity to end up with the equivalent of the by volume mix.

psgugrad,

Good on you for trying the DIY fuel.

I've used home brew fuel for the last 30 years on both glow and more recently Diesel.

I would have thought your 12% oil would be fine for .46 and up engines as long as you're a bit careful with the tuning, smaller engines might be happier on a bit more oil though.

My brew is 18% synthetic which I use on 2 and 4 stroke engines. I've got engines with over 300 hours with no undue wear or corrosion.

Cheers,

Dave H

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Old 08-25-2015, 03:18 AM
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Daver, woops, that's what I call my son, he's Dave also. I am a recovering "castorholic" I have gone through 3 gallons of WildCat 10% fuel they call 2/4 with 18% full synthetic. I have been monitoring my engines, (mostly Saitos), regularly by pulling the backplates now and then. Some of the rear bearings were stained from castor use, they are now shiny and clean. My Fox .25 with a meehanite piston quite literally howls on it with a Taipan 10x6.
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Old 08-25-2015, 03:21 AM
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I have checked 3 RC car blends commercially available off the shelf and evaporated them off so all that was left was the oil. I was verifying what the oil content really was. If mixed by weight, the volume I ended up with would have been wrong. Now I understand this was only 3 brands out of how many, but it makes the most sense to mix by volume. You end up with just a touch more nitro because it's so much heavier than the other components (about 13% heavier than castor oil).

If I used commercially made fuels still, I'd consider emailing some of the fuel companies to find out what method they really use. If one does mix by weight, you could be getting shorted on oil or nitro.

If I'm wrong, please provide information showing such. I prefer to be properly informed.
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Old 08-25-2015, 03:47 AM
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http://wildcatfuels.com/files/specs.pdf

Here is WildCats say on it. I've used their fuel almost exclusively since 1990.

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Old 08-25-2015, 04:47 AM
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Quote:
Originally Posted by FormerDairyFarmer View Post
http://wildcatfuels.com/files/specs.pdf

Here is WildCats say on it. I've used their fuel almost exclusively since 1990.

Blended by volume. Their nitro content is probably a touch higher than advertised which is great. That's the most expensive component in the fuel.
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Old 08-25-2015, 05:57 AM
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Great thread guys, do love my glow engines, they have just got so expensive to run, but the power is awesome, the mess has always been a downer but sounds like it does not have to be that messy.
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Old 08-25-2015, 07:56 AM
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One way to really cut down on clean up is to wax your monokote type of covering. I don't think people take me seriously when I say that, but it makes a big difference in clean up as when you wipe the oil comes right off. Also, the wax keeps the covering shiny and protected from scuffing and the minor surface scratches that cause it to look dull after a year or so. But clean up from glow fuel and bugs is a major plus.
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Old 08-25-2015, 07:58 AM
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Running 12% oil presents the risk of having a much narrower "safe zone" with fuel mixture - if it goes lean, you're in deep doo-doo. Engine wear/longevity can be a problem too. If you guys have luck with it, great! I personally wouldn't risk it, but that's me. I don't mind wiping oil off.
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Old 08-25-2015, 08:17 AM
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Will try the wax thing, thank you!
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Old 08-25-2015, 08:20 AM
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I actually enjoy cleaning my models. It gives me a chance to look them over carefully, examine the control linkages and hinges and look for problems. I think I spend less than 5 minutes on cleanup. I keep a few old bath towels in the car to wipe down a model before I drive home. Then at home I give it the Windex / paper towel treatment.

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