weight to power ratio / which engine
 

Hello Everyone.

I understand Echo are the best weight power ratio engines to be converted, any how in México city where I live, the cost of an Echo trimmer is the same as a brand new DLE Engine.

Are there any other acceptable weight power wise convenient and commercialy available trimmer brand.


Regards.
VÃ*ctor.

RE: weight to power ratio / which engine
 

Stihl, Husqvarna, Tanaka, or Shindaiwa should get you a good running engine to convert in most cases but are just as hard to find cheap as Echo... The Poulan/Craftsman/Weedeater engines (are all made by Poulan) are usually super easy to find because they are the most disposable build but they are also the lightest of the consumer models. At one point I set up one of the old 18cc Poulan 4 bolt backplate engines with prop set up for gas/glow and it was right at 2lb. The downside of these is their out of the box power is quite low, their mufflers are quite restrictive (although some are super simple to gut) and exhaust port timing is VERY VERY tame, I think I measured one at under 120* one time... Open up the muffler and increase the exhaust duration and they might be acceptable, probably not on par with a stock Echo but usable...

Was flying with a guy on Sunday that had a Goldberg stick type plane (W8ye had one, don't remember what it was called) with a 2 bolt backplate 25cc Poulan on EI with the stock 2 needle carb and a stock muffler with 3 quarter inch holes drilled in it, sounded like a flying weedeater but once warmed up ran ok, got to messing around (he was told the engine was smaller, so I brought out a known 25cc to attempt to jump it up a little) and decided to gut the muffler at the field and it then sounded like a flying chain saw and according to him was a completely different plane in the air, looked to be fairly respectable power. I left him with the spare engine with the guidance of telling him to get the exhaust duration to 150*, we'll see how it flies after he plays a little :).

RE: weight to power ratio / which engine
 

Thanks a lot.

I have a converted Mitsubishi 33cc with a larger walbro carb and gutted stock muffler turning a 18x6 arround 6,500 RPM´s but its arround 4 lbs so my weight-power ration is not really good.

Is 4 lb a normal weight for a 33cc converted engine in your experience?

Regards
VÃ*ctor.

RE: weight to power ratio / which engine
 

It takes some work, but I have gotten the Homelite 30cc engines down to around 2 lbs. 11 oz. when running CDI ignition. And if you hop them up, the power is pretty decent too. I have one that turns an APC 16 x 8 at 9400 rpms, and another, tamer one that turns a Zoar 17 x 8 at 8200 rpms. You can often find them in Homelite leaf blowers, and they are more common and cheaper than Echo engines.

The Homelite 33cc out of a Bandit Chainsaw is a pretty good engine too.

Those are the only ones I can think of that are cheap, reasonably plentiful, and make good power. I don't recommend the Weedeater/small Poulan engines as they are low on power and cheaply made in my opinion. From there you go up to the Stihls, Echos, etc., but the price goes up and the availablity used goes way down.

I probably have several engines that would work well for you, but I don't know how I would get them safely shipped to Mexico City if you bought one from me..... Do you have "Estafeta" delivery service there??

AV8TOR

RE: weight to power ratio / which engine
 

I wouldn't seek them out either, but since they're the only thing Walmart sold for YEARS, there's TONS of them out there, I agree on the quality and such though, the 2 bolt backplate engines are nicer than the 4 bolt ones though, the only gasket on those is for the carb, the rest are formed rubber O ring type seals.

Anyway, with oddy's altitude and keeping the current plane flying, putting the engine on a diet or getting a lighter/larger engine would be the best bet, I'm sure there's some weight to loose somewhere, I know my McCulloch 32 has some to loose but most of it's weight is in the crankshaft... Have ideas but the plane flies almost perfectly how it is