tccrab

Am thinking of blending my own r/c fuel and am wondering what about Castor oil makes it the plant based oil of choice.
Am pretty sure it's just for cooling and lubrication, but maybe there's some other magic that it does that I'm not aware of.
Would some other plant based oil like linseed oil, soybean oil or even olive oil work just as well (obviously it has to be soluble in methanol).

Any chemists out there?

TomC

w8ye

My Feedback: (16)

Olive oil has been used here and there

You might try small batches of fuel to find out how it works?

jeffie8696

The subject has been donw to death. Simply put Castor has unique properties that make it soluable in methanol like no other oil. It also lubricates very well, carries heat, seals compression, and when it overheated it turns into a slippery type of plastic that still protects the engine.

Fuel Dinosaur

Got a chemistry degree in my bag of degrees and have been mixing fuels since I was 12 for racing and plain old flying by the seat of the pants. Castor oil is a natural product of a pressing of the castor bean. It does help cool and lubricate the engine. It also has a reasonably good film strength, to stay on the metal parts it lubricates. It also forms long chains in response to high heat and does not boil off as fast as most commercial oils used in fuels, so during an occasional lean run, castor will generally protect as well, or better than, virtually any commercial oil. Compared to many oils, castor is relatively inexpensive. Believe it or not, well oiled engines with castor do not generally have much rust on the engine. I would not use too much castor in most 4-stroke engines and some modelers prefer none. In my own experience, I generally use 2-3.6% castor in all my Saito 4-stroke fuels, the latter in hot summer weather. Castor oil, used at a grade of AA has been a reliable lubricant for model engines for well over 60-70 years or more and is still in use today. SIG sells a good grade of castor, but look for AA grade wherever you buy it.

jeffie8696

Ihave tried some different oils and had no luck at all.

w8ye

My Feedback: (16)

Seems like the simplest thing to do is to go with castor oil and worry about something else down the line

downunder

[link=http://www.georgiacombat.com/CASTOR_OIL.htm]This[/link] article, which can be found on many web sites, is probably the best at explaining the good and bad points of both castor and synthetics. The properties that castor has though are unique as no other vegetable oil has them so trying things like olive oil or whatever is risking the engine if it goes lean.

summerwind

now that was one of the best reads i've seen yet on Castor.
many thx

Sport_Pilot

Interesting fact, both castor oil, and polyethylene glycol make good laxitives! No wonder modelers are so regular!

Wait no, I am confusing my glycols!?

MetallicaJunkie

holy ****...it was interesting

TimBle

well that article covers it nicely.

in effect when you run castor oil in a glow engine, you can call the engine a reformer because it assists teh production of more complex molecules which form a varnish on the metal parts.

that varnish seals, improving compressionor at least maintaining it.

However I believe only aroun 5-10% castor oil really needed in a glow engine, not the 30% and higher than is offered by fuel manufacturers.

razorjack

Model Technics Big Bang fuel has no castor oil at all, only synthetics, what about that?
does it mean that BB is a bad fuel for our engines?

downunder

Synthetics in themselves aren't bad for an engine but you have to be a little more careful never to run lean because they don't give the high temp protection that castor gives. Lean runs aren't just from bad tuning either, a muffler pressure line can come loose in flight and if you're not tuned in to how the engine usually sounds then you can end up with major overheating which causes the synthetic oil to evaporate (then burn) from the piston/liner clearance leaving virtually no lubrication at all. With care though, not a problem but there's always Murphy's Law .

TimBle

Model Technics fuels more modern synthetic oils derived from the esterification of various hyrocarbons, including vegetable oils. Those synthetics are in fact similar o synthetic castor but without the drawback of  the excessive varnish build up since whatever varnish is created is more easily removed.

Theres nothing wring with MT Big Bang, it just uses a oil derived from a better process for manufacturing engine lubricants where high surface tension (film strength) and low evaporative emissions is required. These oils first saw th elight in Europe due to their very stringent Euro Engine emissions standards. In the US, only California I believe has similarly stringent emissions stds.

Sport_Pilot

I thought the US had more stringent emissions? Or used to.   I recall many Euopean cars such as Renult would no longer export their product because they did not want to spend money putting in the enviornmenal controls.  Those that did usually had. significant power losses.  This is easier to do now with compter control of the engines, but I still don't see Renaults and other cars here.  The only exception I am aware of are the cleaner diesel engines they have in Europe, but we do not have the fuel for them.

TimBle

EN228 for petrol/gasoline is currently the toughest std to meet, hence you will see many direct injection petrol cars of european origin in california.

razorjack

So, Is Big Bang better than others then? it's two times cheaper than merlin,jet's etc.

One racer said to me he was using BB once, then, he switched to Merlin and an engine was reaching only 80C, so he could use much leaner setting (to reach proper - 110C temp) - so, he got more power on Merlin i suppose ?

Augie11

I would think olive oil degrades at too low a temperature. Betcha the field smells great though!

TimBle

and you would be correct. However again the more viscous the Olive oil the higher the flash temp and also the difference in viscosity performance with temperature, similar to how different petroleum derived lube base oils of different viscosity behave differently with temperature. The degree of processing is important to understand.

Most vegetable based oils have good performance with temperature, its just that they create a mess inside the engine if you go too high on the temp.

blw

My Feedback: (3)

Generally speaking, the U.S. has been the first to adopt stringent standards and Europe caught up later. Lead free gas wasn't available for some years. We had to take off catalytic converters when shipping cars overseas. I'm not saying our new standards are always good. I have a car that runs badly on ethanol. I was at the beach recently and couldn't find ethanol free gas, so I had to put up with the headaches.

TimBle

Thats true, teh  did get a head start on  emissions legislation but the EU is currently the toughest and California is just behind.
But we must remember the US is a gasoline country so the diesel quality is not matching Europe yet. GSoline is on par with Europe in some states but the diesel is way behind everywhere. 

Sport_Pilot

It's not the quality of the fuel, its the type.  A differant type of fuel is required for high speed diesels used in much of Europe.  But there is a large amount of diesel trucks in the US  that will not convert for a very long time.  A new fuel for a few cars would not be practical.

TimBle

YOu have different grades of diesel in the US, dependant on the state and also the climate. So Sulphur content varies.
However it is a well known fact that low sulphur in conjunction with a lower density reduces emissions. The diesel enginesin your trucks can run on the cleaner fuels but the big barrier is the cost of those fuels. California has Low sulphur diesel at around 15ppm but its not available in much of the rest of the country as far as I know. Yours is a problem of economics and hauler operator behaviour. If more of the passenger car market in the US was diesel then the fuel would be more widely available. Chicken and egg scenario

jeffie8696

All the diesel fuel in this area is low sulfur.

TimBle

Low sulphur it may be at 500ppm. in the US you have No 1-D S15, S500 and S5000 and No 2-D S15, S500 and S5000.

The semantics aside, the highest spec you have is No!-D S15, sold in California and few other states. the majority of your Diesel Fuel is S500 which by definition is not Low Sulphur Diesel since the Sulphur (Sulfur) content onlymeets <500ppm mass requirements.
Low Sulphur by Definition is distillate fuel containing <50ppm mass Sulphur.
Diesel S15 is classified as Ultra Low Sulphur Diesel fuel by international standards.


What really shoots the diesel passenger car market in the foot is the really low cetane of US diesel. It's only 40min. European diesels require around Cetane 47-48 minimum to operate effectively.

Sport Pilot,
not sure what you mean by "type". Thats pretty vague. Diesel is Diesel. Its a hydrocarbon based stream made up of Middle Distillate streams such as Kerosene, medium or heavy naphta, and Lights Oils. Moving from Gasoline to Diesel is a different "type". Whereas moving from Kerosene to Diesel Gas Oil is not so much a different type but a different product stream since both are Middle distillates. Kero being a light cut and diesel using light medium and heavy cuts of Middle Distillate streams. 

You have offroad diesel and On road diesel. Even the on road diesel is either S15 or S500. So its not type of fuel, but "quality" since its the quality specifications of the dieselthat needs to change (ASTM D975 Rev B)