Sport_Pilot

My experience is that the older ST's ran best with a lot of nitro, up to 20% anyway. The old crossflow engines had about the same compression as the US made versions. It was not till the 80's, probably the late 80's that US imported engines had higher compression ratio's.

FlyerInOKC

My Feedback: (6)

I like to use one fuel for everything instead of having several different types and containers. I guess I'm lazy that way.

hsukaria

I would like that too. But my laziness causes me to have 2 blends because I don't want castor in my 4 stroke engines. I am too lazy to clean off the castor from my 4 stroke engines. But I have some older engines that call for all-castor fuel. So, I ended up with 2 fuel blends.

1QwkSport2.5r

Man... You'd probably think I'm nuts for having a break-in fuel (75/25), regular running fuels (5/20, 10/20, and 15/20), as well as my lapped or bushed crank engine fuel (12/23), RC boat fuel (25/20), RC car fuel (20/11), and model diesel fuel. I'm very particular with fuel in regard to what the engine really should have. The only fuels I use any synthetic oil in is the 15/20 and 20/11 fuel, otherwise the rest get all castor. 2-stroke and 4-stroke doesn't matter. A spray bottle with denatured alcohol or clean methanol cleans the engine off pretty quickly and easily. I don't mind.

When I go out for a day of running engines and such, I usually group my engines that I take out to only need one or two jugs of fuel. It only takes a few seconds to change jugs on my field box.

spaceworm

What gas/oil blend do you use in your gasoline engines? Sorry I couldn't resist, i know you abhor even the thought of gasoline, Me too, I use white gas, AVGas, or race fuel, primarily because of the stench of pump gas..

1QwkSport2.5r

The only gas engines I have are on my lawn equipment. Im a devout glow fuel guy, so I'll never have a plane, boat, or car with a gasoline engine in it. FWIW, I use mineral oil in 4-strokes, and synthetic oil in two stroke gas and add about 8oz of 5/20 glow fuel to it. My weed wacker and chainsaw run better with the spiked gas.

I did make a glow plug adapter to use a glow plug in the weed wacker - it works pretty well if I make a heavier gas/glow fuel mix. Regular gas and a glow plug works if you keep the plug heated.

hsukaria

What ratio of gas to glow fuel do you use on your glow/gas engine?

1QwkSport2.5r

The same ratio the gas/glow guys used. 2/3 gasoline and 1/3 glow fuel. They used to say the glow fuel you'd use was 10/10 nitro/oil since gas engines require less oil, but since I don't make 10/10 fuel, I'd just use my car fuel blend which is 20/11 and just open the needles up a little more on the carb. My test engine was an old Ryan weed wacker with a 26cc engine, but I did the test several years ago and only mixed enough fuel for one tank. It was too big of a pain in the butt to have the glow driver connected since the plug was on the bottom. I thought about making a portable generator using a 30cc Homelite (to take camping mainly to charge batteries in the boat) running on gas/glow and use an automotive alternator for the power, but I've had more pressing matters that occupies my time over the last few years.

Hobbsy

My Feedback: (102)

SuperTigre S 90 K with new ST ring and BocaBearings
Fuel==Wildcat 10% with 18% full synthetic
Plug==SuperTigre plug
Exhaust==SuperTigre Quiet Swing Muffler
Prop=====Xoar 14x7
Max rpm==9,650
Idle======2,200 nice and steady

Is this acceptable for a fresh ring and new bearings.with about 12 oz of fuel through it? Thanks

1QwkSport2.5r

Sounds maybe a little low, but more runtime will probably improve that. Mine ran 12,700 on a 13x6 and 11,300 on a 13x8. Stock ST ring and muffler. I never ran a 14x7 on mine. This was after a couple gallons of fuel, so give it time to seat that ring before judging it. 12oz is just barely scratching the surface.

J330

My Feedback: (3)

12 ounces of fuel isn't much break in on a ringed engine, I think another 3 - 4 tanks and you'll see it wake up more as you go.
Why break in with 14X7? A little heavy. I've run 13X7 or 14X6 on these. You'll see a better number of course. I wouldn't recommend peaking it before then. It's not an ABC engine.

1QwkSport2.5r

I run lighter props and oily fuel to break-in myself. Oily 75/25 fuel, 4-stroke for 2-4 minutes and run at the 2/4 break for several tanks. My S90K is still breaking in on the Bowman ring - this engine took a LONG time to break in and run good when I first got it.

Hobbsy

My Feedback: (102)

The 14x7 Xoar was as close to a 14x6, the accepted standard for a .90 sized engine, or so I thought. Then I found a perfectly balanced 14x6 Dynathrust with an exact fitting hole in it. Please spare me the, (worst props ever made) remarks, I've used them successfully for years, as have others.

AllModesR/C

I recently changed brand of fuel and the old Super Tigre doesn't seem to like it. When I ran Wild Cat 10% nitro with 18% oil the engine started instantly and idled perfectly. I did not feel like spending over $120 by ordering four gallons from Tower so I bought a gallon of Omega 10% nitro. Last Sunday at the field I noticed the engine was hesitating to start and had a rough bumpy idle. Putting in a new glow plug helped a little bit but it still has a pretty rough idle. The only improvement I noticed is the engine seems to turn at higher RPMS at WOT with this fuel. I don't have a tach to measure it exactly but I noticed the plane was flying faster and had more power. Any ideas? Easier starting and smooth idle are more important to me than maximum power.

hsukaria

Was there a bug difference in ambient temperature the day you switched to the Omega fuek. It may be that will have to retune the needles with the new fuel, especially Irmo it was a cooler temperature. Colder air will give you more power because high air density.

1QwkSport2.5r

Always start the engine richer - when changing fuels, Richen the high side 1/4-1/2 turn and Richen the idle 1/8-1/4 turn so as to ensure the engine is starting out rich and readjust from there.

Wildcat uses a higher viscosity oil than Omega does, so that's probably a possible issue - also omega has a little less oil in it. Probably need to go a bit richer.

karolh

I've been a big fan of ST engines for as long as I can remember as I found them to be extremely reliable and very user friendly and though lurking I have been following this thread with much interest. Unfortunately the very high cost of glow fuel and it's availability here caused several others including myself to switch to gas engines as the pump gas/oil blended fuel they run on costs peanuts compared to it's glow counterpart, so now the few ST engines that remain are just on the shelve stored in their boxes. Maybe one day the sheer desire of smelling burnt castor one more time might get me running them again......just maybe.

Hobbsy

My Feedback: (102)

I just ordered four gallons of the Wildcat 2/4, I am all castor free now, I have never accepted that certain engines are designed for castor, they are simply designed for something slick to keep the parts separated.

karolh

So true, but IMHO nothing beats the smell of burning castor

hsukaria

I am switching to all synthetic except for my small engines (15s) and old iron/steel engines.

Sport_Pilot

I don't know why you would pay $30 for a gallon of fuel when you can mix it yourself for around $10. It is not hard to do.

1QwkSport2.5r

I'm with ya on that. The investment in the chemicals is high up front, but one batch of chemicals has me covered for two seasons. Roughly $120 gets me about 7-8 gallons of mixed fuel with some of that being 20-25% nitro in buggy fuel. Aircraft fuel is $8-12 a gallon.

I only have a couple engines that will run well on 15% nitro without adding a head shim. I use no more than 5% nitro in my old SuperTigres. The smaller ones seem to tolerate 10% fine, but 200rpm isn't worth the extra couple dollars worth of nitro.

I like castor. It works good.

AllModesR/C

Can you tell me which screws are the high speed and idle? The ambient temp was 75 degrees versus in the low 90's when I ran the Wild Cat fuel.

FlyerInOKC

My Feedback: (6)

High speed has the wire and is sticking straight up, the low speed is on the muffler side pointing down.

5skyhawk172

Question for you guys. I just acquired a 40+ year old Super Tiger G21/46 that is brand new. What would you recommend for fuel nitro and oil content?