correct fuel

[Alan Cardwell 1]

Hiya All,

Just bought an sc46 donkey for my new toy but unsure what fuel to use for running it in, any advice welcome please. Also what glow plug should I use, I have a couple of OS no 8 in stock will they be ok.

Thanks

Alan

[..]

A 10% synthetic oil based fuel will do a good job & the OS no8 is just the job plug wise.

[cymaz]

+1 on that advice. May suggest Prosynth. I personally use 5%...but I'm a tight git, and it's cheaper.

Though I will now be shot down in flames by some people who use other brands and swear by them

Edited By cymaz on 12/05/2015 22:37:47

[john stones 1 - Moderator]

Whatever is easiest for you to get, synthetic oil, nitro% that suits your budget, I use Bekra but that's what our shop sells.

John

[onetenor]

I use home brew with 18% castor oil and if I can afford it 5 % Nitro and run just slightly rich for the first 4or5 tanks full. Then corrcect setting for a few more No8 plug is fine

[Dave Bran]

Around model engines since 60's, never bothered to be specific on fuel, never had poor results. IMO anyone that has a fuel specific engine either has set it up poorly or should be looking elsewhere for their next one.

Just run in a new ABC engine, the number of people who felt obliged to give "advice" was only exceeded by their lack of knowledge of the subject. Shows how many never read the manufacturers information!!

Castor oil is SO 70's, BTW................................. ideal if you enjoy more cleaning than necc.

Grins and gets coat....................................

[ChrisB]

Have been using Southern Model Craft synth 5% on virtually all my engines even big lasers. Also use SMC 10% in a couple of 120s. Never had any problems.

So many fuels to choose from, people tend to stick with what they know.

[Jon H]

Any half decent 5% nitro fuel should do. There is no need for 10% as engines are totally reliable if set up correctly for 5%.

I would also avoid castor oil as much as you can but some fuels contain a tiny bit and that should be just fine.

The formula Irvine sport 5 would be fine, as would the southern modelcraft. Another option would be the Laser 5 fuel. I use this on everything because I mostly fly Lasers and its what I have. My little saito 45 run much better on it than the southern modelcraft I used to use. I have also run it in a plain bearing OS15 fp two stroke, enya 53 4 stroke, Irvine 46 two stroke and a load of asp and OS 4 strokes. All of them have run brilliantly on it. Its also cheaper than the other fuels and it has a lower oil content than most fuels so runs cleaner.

I am sure there will now be an outcry about the idea of using 15% oil but it is honestly more than enough.

[Bob Cotsford]

I too am running anything and everything on Laser 5%, much less gunge to clear up than with other fuels I've used and a very distinctive odour from the ML70 oil.

[Engine Doctor]

Plus 1 for SMC fuel synthetic ,good fuel at a reasonable price.

[Alan Cardwell 1]

Thanks chaps for all the advice I also spoke to Blackburn Models and ended up with Model Technics Quickfire 16, a little bit pricey at £14 for 1/2 gall but I also have an SC25 and an OS15 to run in so it will be put to good use. I also opted for some after run oil as well I just don't know what to with my pension.

Thanks Again

Alan

[Keith Berriman]

Hi Alan If I am not to mistaken MT Quickfire at 16% is what is used in the nitro cars, did they not have any 5% fuel in stock ?? At least with 16% the tick over and pick up should be good I assume other comments may follow

[Jon H]

quickfire is for sure a car fuel. I use it in my 1/8 scale buggy. you should not have been sold that for an aero engine. If you have not used any take it back and swap it for something else as there are additives in the fuel to help with pullstarting. These additives may cause detonation in a higher loaded/lower revving aircraft engine.

As we have more or less all agreed, 5% nitro is plenty.

[iqon]

10% max......

[john stones 1 - Moderator]

I disagree

John

[Owdlad]

I would say there's nothing wrong with the fuel.

Engines in cars / Helis operate in a much harsher environment that is why additives are added to the fuel [to protect the engine through lack of cooling].

Almost likely the fuel advised will be of superior quality than normal plane fuel. As for nitro content..... The more the better...You get better throttle response , more reliable engine runs, an increase in power and cooler running.

Owdlad

[Jon H]

The additives in this fuel advance the ignition point which is fine for a 25000rpm car engine but not for a plane engine. A chap at my old club tried it in an Irvine 46 once and the engine got very angry with him and very hot due to pre ignition.

As for nitro, the amount you use make no difference to the reliability or throttle response. If set correctly the engine will be perfect on 5% or even none. What the nitro does is make the range of needle movement when the mixture is correct somewhat wider and easier to find. Also for those who don't set their carbs correctly or don't bother to adjust a new engines from the factory will find better running with high nitro as the carb is likely set for a richer mixture and this is what you run with high nitro. That is why the engine runs a little cooler, the fuel is acting as a coolant within the engine. As owdlad says, this cooling is very favourable in a heli especially due to its very toasty home and continued high throttle operation.

The big downsides are cost, as you are chewing up expensive high nitro fuel at a vast rate, the mess, and the additional corrosion issues related to the additional methanol in the crankcase attracting water which reacts with the methanol and nitro.

[Don Fry]

This lad is getting very frightened by all this advice. Half a gallon of high nitromethane fuel between three engines, to bed them in, none of which are hot engines, is not going to do any one or anything any harm. And in my experience Blackburn models is not a fly by night organisation.

In the the long term, download the manufacturers recommendations, and (usually ) stick to a commonly available compliant fuel, and broadly stick to that. I say broadly cos you can get away with murder with for instance, low percent oil, no castor, lean runs, new engines, but only AT MOST (with luck) 2 out of 4 at the same time, lest the God Siezedup smite your motor.

Or in my case, 40 years ago seeing my pylon race motor disintegrate in flight, shedding its head unit at high speed in the direction of heaven, with the nose shoved down to comply with Newtons second law, and the resulting backward movement of centre of gravity with it motor missing, exceeded my piloting skills my a long margin. Everything fitted into a small carrier bag. Never found the head. And I was in the lead. Didn't make much of an impression mind, ard me.