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        Discussion OS 37 SZ-H fuel.

#1 Chris56 Dec 30, 2012 03:45 AM

OS 37 SZ-H fuel.
 
Hi,

I am new to this forum, and am blown away buy the quality and quantity of information.

I have just purchased a second hand jr venture 30 with a
OS37 SZ-H, it came with 2 litres of fuel in an unmarked bottle, I have used this fuel and need to buy more, what fuel do i get?

I have a bottle of %10 nitro glo-max that I use in my plane but I think that I need more nitro?

Cheers,

Chris.

#2 Brutus1967 Dec 30, 2012 08:41 AM

If the motor was running OK with the fuel that came with it, most clever thing to do would be to contact the person you bought it from and ask him what the fuel composition was.

If that does not help, I think with a fuel with 10% Nitro and 18% castor will at least keep your engine healthy during running.

I do know that in Europe, you can safely use a fuel with full synthetic oil, in the US, it is wiser to go for at least a 50/50 castor/synthetic mix
In other parts of the world, I really would not know which is the best choice, so I cannot really help you there....

Brgds, Bert

#3 rotoraddict Dec 31, 2012 12:07 PM

Quote:

Originally Posted by Brutus1967 (Post 23658826)
......If that does not help, I think with a fuel with 10% Nitro and 18% castor will at least keep your engine healthy during running.

I do know that in Europe, you can safely use a fuel with full synthetic oil, in the US, it is wiser to go for at least a 50/50 castor/synthetic mix
In other parts of the world, I really would not know which is the best choice, so I cannot really help you there....

Brgds, Bert

Don't get me wrong as Castor does have some positive qualities

I have been running my OS37H (and many other heli glow motors from 32 to 91) on a number of different fuels since it first came out and I found I preferred the fuels with 100% synthetic and NO castor. With the fuels with 50/50 castor, I found that carbon build up inside developed too quickly and coking collected on the motor and muffler in short order. Of note is that you can insure the rear bearings last a long time if you add some after run oil into the motor at the end of the day.

Don't get me wrong as Castor does have some positive qualities, but with the new synthetic oils being used in the modern fuels, they are now my preference. In fact I find just adding about 80ml (about1.5%) of pure AAA castor, to very gallon of synthetic, will help the rear bearings last a bit longer with minimal coke build up.

Here in North America, the engines generally have lower compression then their European counter parts (more gaskets between the head and cylinder) as we tend to use higher nitro fuels that have higher oil content (20% to 23%).

As nitro fuels are double the price in Europe, the European market favors engines with higher compression and lower nitro to keep the costs of running them more reasonable. Then it just becomes a matter of setting the idle screw and the main needle for proper running with whatever fuel you choose.

You can even mix two different gallons to get what you want (e.g. one of 5%N/17% oil with one of 20%N/20% oil to get two of 12.5%N/18.5% oil)

As the OP is from Australia, I would see what engines are generally sold there - those for high nitro use or low nitro use and what fuels are common for heli use there.

#4 Chris56 Dec 31, 2012 08:22 PM

I spoke to few guys at the LHS, they recommended %15 nitro and %22 synthetic oil. I ended up with a litre of this mix to test, and am quite pleased with it. They recommended running a touch richer than I would with castor. They only difference is the amount of smoke, it is like a flying smoke machine.

What is the average cost of a mix like this per litre? I paid $8.40..

#5 Brutus1967 Jan 01, 2013 03:09 AM

Well.... I run my Rossi's on 2% Nitro, 15% all synthetic oil, and that cost approx 3.2 Euro per litre which would be around 4 Aussie Dollar....
15% Nitro, 22% oil would probably cost me around 6~7 Euro, so very comparable to your $8.40

So, fuel without Nitro is not only lots cheaper, but the best thing is, that every 10% of Nitro not only increases your fuel price dramatically, but it reduces energy content of your fuel by roughly the double percentage....
In other words: If you can hoover 15 minutes on a tank 15% Nitro, you can hoover 20 minutes on a tank of 0% Nitro.

So effectively, Nitro is a big waste of money, it only serves to make your motor easier adjustable.

Brgds, Bert


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