Which engine is the lightest (smallest) reliable gas engine on the market?

Thanks,

Cajuncharley

Webra makes brilliant little gas engines: http://www.arthobby.pl/index.php?page=8&prod_id=829 This is a 15 ccm engine, 3 bhp (i dont know if you can trust this number) , and weights only 730 gr- just like a glow one. Proppelers 14x12-16x8.

Doubled post

I have the glow version of the Webra 91 P5 motor and it's very strong. APC 16X6 @ 8900 on 5% nitro. But there is no way a gas version will do that. It has to do better than a ST90 on gas, that's for sure. The BME 90 was down on power, 14X6 @ 9000 rpm. Not impressed.

$550.00 for that 91 is a bit steep, then again the glow wasn't cheap either. I found them for 302 euro or about $450.00 at another site.

If you can find them, BME takes a Super Tigre 90 and converts it-absolutely screams. With the re-organization at BME, they may start making them again, we can only hope.

Have you purchased and run one? I have. They do not make the claimed power.

The smallest realistic gas engine is a 140 sold by RC Showcase. It makes good power for it's weight and size.

There are engines claimed to be released over the next few months in the 180 size range weighing two pounds w/ muffler and ignition with a selling price of $400.00. We'll see.

I am still installing mine in a Frenzy. Another guy at our club has one (actually 3) and he put in a 90 size warbird and we were scared to take it over 1/2 throttle-it just screamed! Now you have me interested/worried.

A guy on ebay sold his engines that were in a warbird twin.

I suggest you run it on a test bench. I found the airflow over the carb sucked fuel from the carb and made the top end go rich-lean rich-lean, it was not saging do to overheating.
One way to avoid that would be to make a curved intake (cut copper or stainless elbow silver soldered to a fender washer) bolted on the carb but it will be very close to the prop arc. I didn't want to bother.

The Heli guys were having problems with these engines sagging, and problems with Webra's too. I don't know what oil mix they were using but you would do best to use Mobil 2T synthetic at 25:1 for break in and then go to 32:1 after a gallon or so. You don't want to fowl that little itty bitty $17.00 plug with carbon!

Running the engine with a 13X8 or even a 12X10 prop will give it better cooling than a 14X6 during break-in. Use a tach and temp gauge if you have one. Tune it for 300 rpm rich during break-in and 100 rpm to fly, according to Keith himself.

You sure it wasn't out of a Cessna because that is the one I got a the other guy in our club snagged the other. Get this-the local auto parts store had those plugs at their warehouse and had me 2 the next day-no idea why they would stock them but was pleased they did. Yup-$15 ea. Hopefully all my switches and batteries will be here for the wknd so I can run it, still about a month away from flying at our field. 25/32:1 sure sounds thick. I use Pennzoil Air Cooled at 40-45:1 (not to get into that debate). We'll see and post what happens.

Rich,

The oil recommended by MVVS and Evo for the little engines is the Mobil 2T and it's designed to be used at 32:1 unlike others. Use what you think is best, run the engine in 3 to 5 minute heat cycles for a gallon, will take a day, post your results. I'll be interested to see what your engine does.

Do you have an infrared thermometer and tach?

I have access to both and will post.

I saw a post earlier about the BME 90 not making the claimed power. I've seen it do it. Can't say why some don't but this particular one did. Fixin to order one for myself.

Trying to report back to all the interested post but my BME we stopped at 12K RPM with a 14-6 and it wanted to go much higher. Going to get a couple bigger props and see what it does because it just seems wrong to run it that fast.

What brand 14X6 is that? I gotta get one! I would have to see that with my original TNC tach to beleive it.

Many new St90 engines on glow won't get to 11,000 on an APC 14X6.

2.8 hp? That's even better than the factory spec 2.5hp on glow running 14,500 rpm!

Master Airscrew K series. I personally have never cared for APC; too heavy and too sharp. Not overly excited by M/A either but they work. Needs to be a stateside supplier for Hawk!

MA-k flex and flatten out. All you have to do with an APC is hit the edges with a piece of 320 grit when you check the balance.

If you flew electric would you still use MA-K? Sorry, couldn't resist.

Electric? Sorry don't speak that language....(holding out to the bitter end)

I know it's a bitter pill but they can be fun on a Sunday morning in the back yard or local field down the street compared to having to drive 25 or more miles for a fix. The technology is really getting good. Another year or two and it should be painless. Painless that is unless you accidently hit the thottle after the ESC is armed while the blades are close to your skin. If you think a small glow or gas could be dangerous try a tiny electric motor that won't stall. They can turn into a Bass-O-Matic and will not stop until the power is cut off.[X(]

I'm not sure why but people get irritated at me when I tell them that I could fly from my 10 acres if I wanted to but don't because I am only 5 min from our field (oh, and make all the noise you want). Can't put my finger on it..... [sm=50_50.gif]

Very Nice

Getting back to this engine-do you think there is anything wrong in running it that fast or am I stuck in a 50cc mentality?

If it's truely making that kind of power and noise is not an issue, enjoy! The engine will run cooler than if it's loaded down to 9,000-10,000 rpm.