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Nitro help

Old 10-02-2016, 07:47 PM
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mashp39
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Default Nitro help

I am using 46 size OS Max and Super Tigre engines.I have heard ST engines don't need nitro fuel. Max engines do. Would a fuel with nitro work for both engines? What nitro would work best for both engines?One plane is a Big Stik and the other is a Kougar Mk II.I have been using a fuel with 5% nitro and it seems to work in both planes but what is your opinion?
Old 10-02-2016, 08:04 PM
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What does the instructions say?
Old 10-03-2016, 05:08 AM
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mashp39
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What instructions? These are engines I have acquired on E-bay or swap meets.I don't buy new ,off the shelf. I just wanted a general discussion on what others have tried or used.
Old 10-03-2016, 05:30 AM
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mashp39
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After I googled your question, I have found an answer. Os engine 10%, ST 10-15%. So I will use 15%.I don't know where I heard ST no nitro. Just an idea people get and pass on I guess.If anyone wants to give a recommendation or past experience I would like to hear Thanks.
Old 10-03-2016, 06:37 AM
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Glad to read that you found your answer. Almost all of my engines take 50% or higher to get them to run well but, then again, all but one have water cooled heads. The exception to that is an OS 25FP, which takes the 10% you found
Old 10-03-2016, 08:55 AM
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All Super Tigre and OS engines run just fine on anything from 0-15% nitro.
I myself use 5% nitro in all my engines but it seems that many americans prefer 15%.
The old Super Tigre engines (Italian made ) were all made to run
fine with 0-5% nitro but the newer Chinese made Super Tigre engines are more like OS engines and tolerate a wider span of nitro.
Old 10-03-2016, 12:46 PM
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mashp39
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Thanks for your input. I just bought some 15% nitro and will try it next week.
Old 10-04-2016, 02:35 PM
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jester_s1
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Too much nitro won't hurt anything even in a old ST engine that has the high compression. It will just require you to to tune it more rich to retard the ignition timing which hurts your power. But if the engine isn't designed for that much nitro, you won't get the power benefit for the money you spend.
Old 10-05-2016, 07:20 AM
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Agreed. What many don't understand is that the amount of nitro in the fuel actually REDUCES the amount of actual fuel in the mix, that being the methyl alcohol if I remember right. An engine set up for higher RPM levels and larger loads, usually a ducted fan or marine engine, would benefit from higher nitro contents where a typical sport aircraft engine would still run well on low levels of nitro. I found this to be true with the engines I have run over the years. I found that my OS 25FP runs great on 10% nitro with 18% oil while my marine engines, ranging from .21 to .67s, don't run worth a hoot at less than 50% and 18% oil. I also found that too much oil(helicopter fuel in my case) will reduce the engine's output while too little(meaning car fuels) cause internal parts to wear faster than they should
Old 10-05-2016, 01:41 PM
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What nitromethane actually does is add oxygen to the fuel mix, requiring the engine to be tuned more rich than it would be without it. That's how it improves power, by making the engine burn more fuel. But a side effect is causing the ignition of the fuel to happen earlier (not an issue with a spark igntion). Compression and the heat of your glow plug also influence the ignition timing. So if you change one thing, you'll either have to compensate with something else. Engines that are meant to be used with lots of nitro have much lower compression and use cooler glow plugs. They make tons of power at the expense of good idling and acceleration and are very sensitive to tuning.
Old 10-07-2016, 08:41 PM
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I agree with Jester, the nitro increases the oxygen content allowing for less fuel and a more complete burn of the fuel. I use 15% in all my engines and I am quite pleased with their performance.

Frank
Old 10-08-2016, 04:36 AM
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mashp39
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That's what I was trying to get. More of a burn for the fuel that will result in a better idle and less dead sticking.More power would be OK also.
Old 10-08-2016, 05:28 PM
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If you are having those kinds of problems with 10% fuel or even 5%, something is wrong. Any glow engine should be reliable enough to maintain a reasonable idle with any fuel. I'd check your fuel lines for air leaks, make sure bolts are tight, and check the liner for peeling to see if there is a mechanical issue. Of course, bad tuning will cause deadsticks too.

To clarify, nitro doesn't give you a more complete fuel burn. It adds oxygen which lets you burn more fuel. It basically does the same thing for a glow engine that nitrous oxide does for a gas engine.
Old 10-09-2016, 05:43 PM
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I have run 5%, 10% and 15% at various times. Honestly, my OS, TT, Fox, Enya, and Saitos run equally well on all three. I now run 5% on everything.
Old 10-11-2016, 02:34 AM
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I've noted about a 200rpm boost for every 5% nitro I add to the fuel. Rare example was with an Enya 15IV that gained 1000rpm going from 0% nitro break-in fuel to 15% nitro. But as I said - this was a rare occurrence to gain that much power.
Old 10-11-2016, 07:21 PM
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mashp39
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That is the answer I was looking for. I am not having any problems with 5% but I wanted to know if more nitro would be better at all or just what would be gained. There has to be a reason for more nitro or why make it. Also if the 15% would work in both engines.I didn't want to help one engine and hurt the others running.Also one fuel to have not two.
Old 10-22-2016, 11:15 AM
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mashp39
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I ran the 15% today in an old Super Tigre 51 and it did great. Great transition from idle to mid-range to full power. No hesitation at all. The idle had to go all the way down on the trim to finally shut off.As far as I am concerned the 15% is a big improvement over the 5%. I will use it from now on. Thanks for all the input on this subject.
Old 10-25-2016, 07:31 AM
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I am glad to have read this thread . I have learned some new information . Thanks guys .
Old 10-25-2016, 06:55 PM
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mashp39
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Great! I was hoping to generate some useful dialog. Good answers, not just question bashing.
Old 10-29-2016, 12:53 AM
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Originally Posted by mashp39
I am using 46 size OS Max and Super Tigre engines.I have heard ST engines don't need nitro fuel. Max engines do. Would a fuel with nitro work for both engines? What nitro would work best for both engines?One plane is a Big Stik and the other is a Kougar Mk II.I have been using a fuel with 5% nitro and it seems to work in both planes but what is your opinion?
Here are the links to manuals for your engines:
http://www.osengines.com/manuals/index.html
http://www.supertigre.com/manuals/index.html

In the USA 10% and 15% nitro are the most popular for most fliers including a lot competition. The quality of the fuel is very important as some manufacturers use lower grade ingredients. Also, everything should be measured by volume and NOT weight to get the correct ratios. Powermaster and SIG are examples good grades of fuel.
I've also been using fuel from brodak.com which I think is rebranded Sig it works very well too.

I've been running Super Tigre and OS 2 and 4 cycle for many years. Both 2 & 4 stroke OS on 10-20%. The Super Tigres up to 40% nitro.
The fuels I chose always have castor oil in them, always! 50/50 mix is a good balance.

Great question and answers by everyone.
Old 10-29-2016, 05:11 AM
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I really liked SIG fuel when I used it. I basically use the same thing as SIG that I mix myself, but I tailor the oil package to the engine design. Most average ringless aluminum piston engines will run well on 20% oil and 5-15% nitro. I recommend a minimum 50/50 castor/synthetic oil ratio.

I do not recommend using a fully synthetic oil in OS engines - they have a propensity to peel the liner if run hard on synthetic oil. Otherwise they seem fine most of the time.
Old 10-29-2016, 06:06 AM
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jester_s1
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IMHO, 20% oil is simply not needed anymore. The synthetic lubricants do have better lubricity, so our engines will run fine with less. And there are benefits to that. Oil cools your glow plug and slows down combustion, reducing your power output. I saw that firsthand with my Novarossi. I broke it in with Omega fuel with extra castor added to make it 20%, then changed to regular Omega which is 17% blended oil. Top end power and acceleration improved instantly just from the fuel change. There are guys running 14% full synthetic oil in ABC engines with no ill effects, but I do think that's pushing one's luck. I'll also mention that helicopter engines are nearly all running full synthetic 17%-18% (depending on the brand) and aren't seeing any durability problems.
As for OS engines peeling their liners, that was a major issue on the FX line. OS didn't have their ABN plating process right, so the engines that peeled probably would have done so regardless of the oil being used. OS did a half hearted response in fixing them, which was a major dent in their reputation. But it looks like they fixed the problem in the AX line. I know plenty of guys who run full synthetic in OS engines and haven't had any problems.
Old 10-29-2016, 06:31 AM
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1QwkSport2.5r
 
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Originally Posted by jester_s1
IMHO, 20% oil is simply not needed anymore. The synthetic lubricants do have better lubricity, so our engines will run fine with less. And there are benefits to that. Oil cools your glow plug and slows down combustion, reducing your power output. I saw that firsthand with my Novarossi. I broke it in with Omega fuel with extra castor added to make it 20%, then changed to regular Omega which is 17% blended oil. Top end power and acceleration improved instantly just from the fuel change. There are guys running 14% full synthetic oil in ABC engines with no ill effects, but I do think that's pushing one's luck. I'll also mention that helicopter engines are nearly all running full synthetic 17%-18% (depending on the brand) and aren't seeing any durability problems.
As for OS engines peeling their liners, that was a major issue on the FX line. OS didn't have their ABN plating process right, so the engines that peeled probably would have done so regardless of the oil being used. OS did a half hearted response in fixing them, which was a major dent in their reputation. But it looks like they fixed the problem in the AX line. I know plenty of guys who run full synthetic in OS engines and haven't had any problems.

The AX and AX II engines can and have peeled. Lean runs or poor quality fuel may be a contributing factor, maybe not.

Running lower oil content and higher or all synthetic oil doesn't seem to hold up at higher temperatures that will protect against a lean run - the term I e heard it called is "unzipping". I personally wouldn't chance it, and I personally am not after every last rpm. Use full castor in many engines and a castor/Klotz blend in a few others including Picco, Novarossi, and Dub Jett engines. They run smooth and transition good and in several cases run higher top rpm than other guys with identical engines using commercially made fuels. So while I support your notions for the most part, I do think guys that aren't as experienced stick with 18-20% oil and the more experienced guys can do whichever they know to work.

Novarossi recommends 20% oil (50/50 blend) for aircraft and 10% oil (30/70 blend cas/synth) for boat and car engines. I doubt a novice would use a Novarossi engine, so an experienced guy using say 15-17% oil in an aero engine is probably fine.. But a novice should use 20% IMO.

Last edited by 1QwkSport2.5r; 10-29-2016 at 06:40 AM.

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