Frank B.

My Feedback: (1)

Update: tested with a 15x8 and 18x5, scroll down to the props for results.

I looked at all your guys conversion so I had to try one for my self,

The engine is out of a Featherlite FL1500LE 23cc leaf blower, this has the long shaft and the small transferports (low performance version) I was disappointed!

Bore 34.44mm
stroke 26.40mm

Displacment is 24.6cc, the box says 23cc??

Stock port timings are:
Exhaust port duration 139 degrees
Transfer port duration 92 degrees
Intake duration 120 degrees
Head clearance stock is .044

Mods that I did to the engine were:

Machined .020 off the bottom of the cylinder

Machined .020 off the top of the intake port (no other mods to the intake port were done)

I skirted the piston for better flow the the transferports

For the transferports I did not widen them, I increased there duration only
Primary transfer ports were increased to 124 degrees duration
Secondary transfer ports were increased to 128 degrees duration

The exhaust port duration was increased to 155 degrees

The intake duration was increased to 124 degrees resulting from lowering the cylinder .020

And the new head clearance is .024

I stuffed the crankcase by adding a piece of .300 thick nylon plastic to the back cover

The muffler and prop hub are from wackerengines.com (excellent service from them BTW)

The carburetor that I used is a walbro WA 167A

Fly wheel was lightened

I machined some of the excess cooling fins off the cylinder to save some more weight

The engine weighs 3 lbs. 5 oz. with everything on it ready to run

Perfomance so far after about 1/4 gallon through it of regular gas mixed at 32:1 of Klots R-50 synthetic is:

15x8 @ 8600 rpms
16x8 @7600 rpms
16x10 @6900 rpms
18x5 @ 7300 rpms
18x6 @7100 rpms
18x8 @6400 rpms


Frank B.

captinjohn

Frank B: Very good work on the engine with good results. You also done a very good job of placing a lot of good data here for us. Thanks Very Much Capt,n

Flight Risk

My Feedback: (1)

Frank,
All the FL1500LE's I see are 18cc. Evidently the LE stands for low emissions, which may account for the low performance model. I just purchased a Featherlite XT260 trimmer which said 20cc on the box but was marked 25cc on the head. If it really is 25cc you would think that would be a selling point for the box. I have started removing excess material and appreciate seeing what you have done. Is it common to trim the cooling fins on these?

Rod S

captinjohn

I would say it is common if you got a lathe to cut fins some for a better look. In most airplanes you have lots of cooling air...but not all. If you are going to do a gas/glow...it would be helpfull to cut the very top most fins back to keep a warm glow-plug. Capt,n

Frank B.

My Feedback: (1)

Right, like the captin says, all the cooling area of the cylinder is there to utilize the air flow from the flywheel so it would be over kill in an rc plane flying at 40 + mph with good air flow through the cowling.



Frank B.

Flight Risk

My Feedback: (1)

Thanks Capt,n and Frank, It makes sense that the fins could be trimmed. I've heard that small displacement engines run considerably cooler than similar engines of large displacement.

Rod S

captinjohn

I guess on cutting back the fins, you may want to consider if you live in a super warm climate....you may want more fin area. In cooler climates less fin area is fine. Up north here, we do not fly in the heat of the day that often. The cool part of the day is a lot more comfortable. Capt,n

Frank B.

My Feedback: (1)

Here is the poulan mounted in a seagull Yak 54, it fits pretty good.

captinjohn

Hey they engine looks good in the Yak 54. I bet you cannot wait to fly her!!!! Capt,n

Frank B.

My Feedback: (1)

Yes I cant wait to see how this engine will perform, everything weighs 10.1 lbs ready to fly, the wing loading is 27.5 oz/ft and according to the prop thrust calculator the static thrust is well over ten pounds with the 18x6.

Frank B.