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Old 04-22-2004, 05:19 AM
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I have been using hotstuff 20%synthetic and 5% nitro for a while in my TT .46 Pro for some time and has been fine. But I wanted to try straight castor for once to see what is was like. Its better protecting quilties is what interested me. So I started it up and it idled good but as I went to full throttle it was really really smoking. Even at peak setting on the neddle. I filled up the back yard with smoke in about a minute. Never happened before. Is this because of the castor fuel. And the motor seemed to be running a tad slower then normal. Do you need a hotter glow plug or something. Im using an OS #8 plug (HOT). Why is it smoing so bad.

Any help

Old 04-22-2004, 09:12 AM
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I use straight castor at times and it seems to smoke a bit more. I have been using a blend more than anything for the last few years. Might try a bit more nitro if you want it to run a tad hotter. I run 15% in everything but my 25 and smaller engines any more. I run 25% in those.
Old 05-11-2004, 03:01 AM
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I would highly recommend that you add about 5 - 10% Castor to your Oil Content
(90% synthetic and 10% Castor)
Castor WILL give you protection against a lean run and Lube your engine after use for
bearing protection from rust.
Have a read of the article below.
As a bonus protection for my Engines, I ways spray some WD40 in to my Engine after I've
got all the fuel out of them by flicking over the Engine with Glow ignited and Fuel line disconnected. But: only use the WD40 from New or after you have "Decarbed" your engine.
I had an OS 25FSR which I ran total Oil content of Castor for 10 years (No Synthetic) whilst using WD40. There was NO Carbon build up at all on the Piston / Cylinder Head!

All the best, DFT.

Castor in the Fuel.

Don't flame me guys. I'm a manufacturer of glow fuels and am constantly discussing this castor / synthetic topic with my retailers and sometimes the customers.

Most of my blends are a mixture of synthetic and castor. Reasons are simple:
Castor is the best corrosion inhibitor we can use in our alcohol-based fuels.
Castor provides a little more scuff protection, especially the piston & sleeves for ABC types and on the crankpin/connecting rod.

Castor does have a slightly higher flashpoint and the varnish is actually a lubricant.

Castor has a few downsides as well, everybody has mentioned the carbon. Yes if run too hot for too long an excessive amount of carbon can accumulate on 4-stroke valves, ring lands, and piston tops and combustion chambers. 4-strokes seem to be the worst affected when more than 4% is used.

Castor will not mix readily with high concentrations of nitromethane in the fuel. Castor when dried (let sit) turns carb barrels and bearings into inanimate objects.
Castor foams like crazy in methanol.

Synthetics, when a premium one is used will have a flash point within 50 to 75 degrees of castor and not leave significant carbon deposits.
The good ones will flash clean and still provide protection up to that flash point. The premium synthetics are very slippery, much more than castor and also provide much less surface "drag".

Synthetics for glow fuel use do not have as much "impact cushion" as castor does or as much scuff protection, but the premium ones are real close.
Synthetics (without additives) do not provide any corrosion resistance.
Synthetics are a natural anti foaming compound when in a methanol solution. Synthetics will mix with nitromethane in any ratio.
Synthetics will not dry into engine glue like castor; it’s a very stable chemical.

The synthetic / castor debate will never end. But the longer it goes on, the closer synthetics get to the overall good points of castor.

My best recommendation is to run what you are comfortable with and understand each lubes strengths and weaknesses. Me personally, I believe in a mix of the two to maximize the strengths of both and minimizing each other’s downsides.

For four strokes, I’ve found that running at least 2% castor (by volume) but no more than 4% castor with the balance of 20% total being synthetics you can keep the carbon down and the overall protection up. Just a little castor in a four stroke can do wonders for longevity and rust protection without having any of the all castor downfalls or synthetic downfalls. I have also found that 2-4% castor will not gum up the regulators in YS engines, even after sitting.

For ABC type engines, I have found that 4% castor will provide all the scuff protection needed for normal sport flying when the remaining 16% is a high quality premium synthetic.
Old 05-11-2004, 10:23 PM
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I frequently run some of the iron piston engines on 5% nitro and 25-28% castor and dont notice significantly more smoke than when running engines on blends, richness being equal of course.

Old 05-12-2004, 06:59 AM
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DFT, do most fuel manufacturers use the premium synthetic in their fuel. How can the consumer tell if a company is using a quality synthetic oil?
Old 05-14-2004, 08:24 AM
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I sell only one brand in my store because i know what is in the fuel. The oils are the same as used in drag cars. The oils work on 7000hp nitro fueled with no cooling problems they will work on our engines. Wild Cat is the best I've found. Dennis
Old 05-14-2004, 08:56 AM
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Wildcat is not shy when it comes to letting you know what is in their fuel. Their website has lots of good info about contents, properties and pros & cons of different lubricants. Check it out for more info:[link][/link]
Old 05-14-2004, 09:54 AM
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The smoke you see is partly evaporated castor oil. Depending on how you look at it it's a feature :-).
Since castor oil has a higher viscosity than the synthetic oils commonly used i model engines, friction in the engine will be a little bit higher, thus reducing the max rpm somewhat.
Changing the plug will not change the amount of smoke produced. How hot or cold the plug is determines the ignition timing of your engine so if your engine is running fine keep the OS8.

/Red B.
Old 05-14-2004, 11:15 AM
Jim Thomerson
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A couple of years back Larry Driskol (spelling?) published results of a fuel test in his CL combat column in Flying Models. He was testing 1/2A combat engines. Results were that maximum HP was with all castor fuels as compared to mixes and all synthetic (as best I recall). One reason you get more smoke with castor is that the castor goes through the engine doing its job all the way and comes out as a vapor, while some or all of the synthetic is burned in the process. The burning of the synthetic may give a little more power, but I doubt that burned synthetic is much use as a lubricant. Of course if you needle your engine right, it doesn't get too hot, and this is all moot.

Old 05-29-2004, 02:31 PM
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hi rossco
what percentage of castor oil were you using? I am from the old school and do not like the synthetic lubs, always use a castor blend. castor oil does give you as added protection in case of engine going lean. I would use about 22 to 24% castor oil if you are blending your own. and if using fuel with straight synthetic oils, they usually run around 18% I would add enough castor to bring total up to about 22 to 24%. if you were smoking that much it could mean you were running really rich or oil content may have been a little high.

happy flying

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