Walther

My Feedback: (1)

RCmodeler 85.

FlyerInOKC

My Feedback: (6)

Which month please?

Hobbsy

My Feedback: (102)

I'm thinking about selling one of my 4500's, it never had fuel in it, it will include a Bisson Pitts muffler and engine mount.

Hobbsy

My Feedback: (102)

No post

Sport_Pilot

Just buy the methanol, oil, and nitro and mix to the percentages you want. Lots of posts in the fuel forum.

1QwkSport2.5r

I would not run more than 10% nitro in the older ST engines. Any fuel with 5-10% nitro and 18%+ oil (at minimum a castor/synthetic blend) should do well. I prefer SIG Champion fuel if I didn't mix my own.

FlyerInOKC

My Feedback: (6)

Super Tigre always did have a reputation for low Nitro fuel, the bigger the displacement the less Nitro it preferred.

Bax

My Feedback: (11)

SuperTigre, themselves, preferred 100% castor oil as the lubrication, and designed for it.

FlyerInOKC

My Feedback: (6)

I love the smell of Caster Oil in the morning! Mix it with your coffee it will keep you regular! ;-)

1QwkSport2.5r

My S90 was an incredibly picky engine when I got it nearly new and broke it in. After an hour on the bench (on 5/20 fuel) it flamed out all the time. Couldn't get a reliable run out of it to save my life in real use (again, 5/20 fuel). Went to 80/20 FAI methanol/castor fuel for a couple gallons and it would then tolerate 5% nitro. I suspect it took a long time for the ring to seat and perhaps why it was finicky. I re-ringed it and now it surges a couple hundred rpm from peak down to 1200rpm rich of peak. I used a Frank Bowman ring gapped at .002". Need to try some other plugs and props (though the plug I'm using is the same brand and heat as I used previously).

I have used 10% nitro in an S29 and an old Italian GS45 with perfect running character.

hsukaria

I have a G51 that has used 5 and 15% nitro fuel. The throttle transitions with 5% are better than 15%. With 15% nitro fuel, it was too rich in the mid-range.

Would I be able to run it with all synthetic oil like Cool Power with no ill effects? I have run it with blended oil or all castor in the past.

1QwkSport2.5r

All of my close RC friends that have used cool power and didn't have good results from it. Engines ran hotter, one even had an engine sieze on it (probably due to heat). I would always advocate at least 2-3% castor minimum in the fuel. That is unless you use an Ester oil like. Motul Micro or the like... That oil is awesome by itself without the need for castor, but it's mega expensive.

hsukaria

I was hoping the Ester oils would become more common and less expensive, but I don't see that happening.

The reason I asked about the fuel is because I run my 4-strokes on 20/20 fuel (all synthetic) with good results but I have a few older engines that require 5% nitro and 20% all-castor. So, maybe for the engines in between, I could mix the two fuels and get a 12.5% nitro, 10% synth, and 10% castor. That way I would only have to purchase to fuel blends for all my different engines.

1QwkSport2.5r

As long as you can tune a needle pretty good, you can maybe get away with it... But I would caution running those old ferrous engines that were run with castor based fuel on fuel with a bunch of synthetic oil. I've heard many times a good running ferrous engine go to pot when run on fuel with a lot of synthetic oil. If run from new with a blended oil, it'll probably be okay. Some guys have gone to all synthetic in lapped engines from castor fuel and haven't had any issues, but long term longevity remains to be seen. Personally I feel running those old engines means running fuel of the period. Newer technology engines are more tolerant than the old ones.

hsukaria

I always run the old lapped iron piston engines with all castor. I was just wondering if the Super Tigre G51 (ringed made in China) would tolerate all synthetic oil.

Hobbsy

My Feedback: (102)

I just sold my SuperTigre 4500 in about 1/2 hour, I had a misfire on selling it yesterday, re-did the AD and it's gone. I still have one though. Not to fear.

1QwkSport2.5r

The G51 should run fine on it - just know the limitations of the synthetic oil and tune the engine accordingly and it should be fine.

Charley

My Feedback: (2)

Why not? I ran 15% nitro in several Italian STs in the 1980's when I lived in El Paso, TX, @4500' MSL. I took two of them to Houston for an AMA fly-in. Guys there told me 15% would overheat my engines in the high humidity and sea level pressures. I said uh-huh and continued to fly my models all weekend.

CR

1QwkSport2.5r

In high elevations higher nitro is fine. Closer to sea level, I wouldn't chance it. I've run 10% in .45s and smaller, but nothing larger. I ran 15% in my .90 and I thought I was frying a pan of bacon! The engine sounded horrible. I went back to 5% and it ran normally and sounded normal. The glow plug looked like it went through hell and back (it was new before the test on 15%), so I changed it. Been fine since. So for me, I would not ever run more than 10% in a smaller ST or larger one for that matter without adding a head shim or two. If it worked for you, great. I wouldn't do it myself or recommend it to anyone without having some head shims on hand first.

FlyerInOKC

My Feedback: (6)

My .40 China built Tigre on my LT40vhas no problem with 15% Nitro but I like to run it a little rich.

1QwkSport2.5r

The newer ones seem to be more tolerant to higher nitro than other models I've noticed... If it works for you, by all means do it/use it. I have only noted a 200-300rpm gain for every 5% nitro I add to the fuel. My .90 ran the same peak rpm +/- 100rpm on 15% than it did on 5% except it crackled like no other. My little S29 gained about 300rpm on 10% from the usual 5%. So it definitely seems to add creedance that perhaps the smaller engines aren't as highly compressed as the larger ones and as such tolerate nitro better.

I had one weird one that threw me for a loop - an Enya .15IV on a 7x5 or 7x6... From 5% nitro to 15% nitro it gained over 1,000rpm. That was a wild ride!

Ill just add - I like using cheap fuel. 5% nitro 20% oil fuel is super cheap to make and the engines run fine on it. I run most of my European engines on 5% just because they tend to run better plus the fuel is cheap. So YMMV and if it ain't broke don't fix it.

hsukaria

Plus castor oil is usually cheaper than synthetic oil. So, 5% nitro and 20% castor is the most cost effective for my 2 strokes.

1QwkSport2.5r

Me too. Roughly $6-8/gallon. It lasts a bit longer in the tank than 15% too.

hsukaria

About 10% longer, which is the difference in the nitro content. The Fuel to Air ratio only relates to the oxygen in the air and methanol in the fuel.

Sport_Pilot

My experience is that if the engine isn't real tight you get a small performance boost with synthetic oils. But if not then it will run hotter than with castor. And no protection from a lean run.