Hi guys!

What's the best string trimmer engine to convert in the 31cc - 38cc range?

TIA!

Dr.1

Echo/Kioritz engines are probably the best, at least in my experience. It sounds like you want more power than the usual weedeater which is most often in the 18 to 28cc range. Look into leaf blowers, or better yet, chainsaws. Homelite makes a good 33cc engine chainsaw, and as I said, Echos are great.

AV8TOR

I agree with everything Av8tor has stated. Look also for Homelite Powerstroke chainsaws. They are very easy to convert and the 2 I have done have beam mounts which makes mounting like the Echo 44 and 50 cc saws.

Thanks guys. I'm looking for an engine to power a GT 1/4 Fokker Dr.1 that'll probably weigh 14-16 pounds. I'd like to turn a larger, flatter prop than the 18-6 recommended by GT on a Zenoah G-26. I'm also looking to cut the cost over a new G-26 which, at $275 for a magneto and $300+ for electronic will cramp the CC greatly. [:@] I've thought about the BCMA engines, and the venerable Zenoah G-38. There again, cost is a factor.

Dr.1

I have an Echo 23.6cc engine and an 18 x 6 APC prop on my Great Planes Fokker Triplane. Pulls it around quite nicely. Loops, Immelmans, etc. are no problem from level flight. I never weighed it, but I would guess it to be around 13 lbs.

AV8TOR

how about a stihl 28cc like this.comes from an FS-46 if i remember right.engine weighs 3 lbs as in the pic.it can use the 3 lugs for a firewall mount and as a beam mount.the pic is how it comes from the trimmer,hardly no cutting involved.

there is a pretty steady stream of Zenoah g38's on eBay (mostly used, a few NIB). Used ones in good condition seem to go for about $70-90 inclusive of shipping, NIB as much as $200 inclusive. The G38 w/b (IMHO) an EXCELLENT engine for the GT DrI, would provide more than enough power (enough for STRONG aerobatics). If budget is the driving concern, I think I would drop back to one of the leaf blower engines in the 25cc range. There are some of those around (on eBay now) for about $25 each plus shipping. They are VERY easy to convert (some easy cutting/grinding), make a flat plate mount, add a prop hub and you are ready to go. For your purposes inside that huge cowl, you could use the stock muffler (gut it out to allow better flow) and not bother w/ trimming the flywheel as the vanes face aft anyway. You probably will want to swap the carb for one w/ 2 needles for better adjustment capability. IT will provide adequate power as the DrI is not a speed demon anyway, should be very scale.

Of course, the venerable Ryobi 31cc is always worthy of consideration. Plenty of them around still. Power isn't great but should be adequate for that application. Very easy to convert, plenty of conversion parts around (as well as converted engines). You might have to modify the firewall to allow for the length of the Ryobi as it has the carb on the back of the crankcase.

Look also for Homelite Powerstroke chainsaws.

Is that the same engine as the Powerstroke 23cc on a string trimmer I saw at Home Depot?

Dr.1

I would think they do not have the easy beam mount capability and would require more work. Still can make a good plane engine out of them I am sure.