Fuel Dinosaur
Posts: 85
Joined: 6/25/2002
From: Warrenton,
GA, USA
Status: offline
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Downunder,
You are right, there are many suggestions made on fuels today that make little to no sense. No castor in a ringed engine is nonsense. Also, before George Aldrich passed away, I had many e-mails from him about fuel formulations. What he refers to as Koolaid, some refer to as green snot. We agreed entirely that there was no real reason that you cannot use, he said 5% and I said 0-4% castor in 4-stroke fuels. I was not going to argue much over a 1% difference! I have heard ALL KINDS of arguments about voiding warranties, gumming up the top end, leaving carbon on the piston and exhaust port. What I find in fact, is that all my Saitos all run fine on 2% castor up to 3.6% castor in summer they run cooler and perform great. Getting some junk on a 4-stroke piston in 3-4 years use is NOT much of a problem. On 15% nitro, these engines develop good power, idle well and run cooler, so why not add a little castor? To the converse, guys in our club who used one half castor/half synthetic fuel were asking for trouble with that much castor. As with many things, the Greek golden mean and the truth lies somewhere between these two extremes.
Also, I see a 2-stroke/4-stroke fuel that is all synthetic. This is okay for the 4-stroke engines, although not to my taste, but this is not that good for the poor 2-stroke engines. Many 2-stroke engines will run fine on about 20% of the oil being castor to about 50% and last a long long time, and as you know, some will run all day on a straight castor based fuel.
For the record, in case the newbies are confused somewhat about what an FAI fuel actually is, it is currently an 80/20 blend of methanol and castor oil, period. The older formulation was 75/25. A few manufacturers DO offer a 1:1 oil blend of synthetic and castor, but this is a pseudo-FAI fuel in technical terms.
I am sometimes astounded at the horror some modelers exhibit when they see some GOO on their airplane. I can promise you this goo is also on the bottom of their connecting rod and one the crankpin in that small .002-.004 or thereabouts slip on the side of the bushing. The notion that all of our current oils are that much better than in the old days is not quite true. Some of the best oils were just too expensive and seldom, if ever, found their way into commercial model fuels. Why people avoid castor that has a flash point well over 500 degrees F and great viscosity and accept oils that flash away around 400-460 degrees or so is beyond me. There are clear advantages to both synthetics and castor and the combination, properly selected, is often better than one or the other alone. I feel compelled to respond to fuel type questions even if it is not quite what some folks want to hear. I noted on one site yesterday that the ideal fuel for most 2-stroke engines was a fuel containing about 20-22% oil and 10-15% nitromethane. This is probably a true statement for longest engine life consistent with decent performance. They then proceeded to sell a fuel with 17% all synthetic oil to their customers. No wonder modelers are confused about what their engines actually need.
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> Cool Power 15% on OS .46 FX? 
Cool Power 15% on OS .46 FX? - 
COOL POWER 15% - 
Fuel for Thought re: OS 2-stroke - 
Morgan fuels also have what they call FAI fuel which is a 17% all synthetic (Coolpower) or a 17% blend (Omega). This is NOT an FAI fuel so if they don't know what they're talking about with something as simple as this then how can anyone expect to believe the rest of their claims?