helodrvr

My Feedback: (88)

Hey Guys,

Just purchased a slightly used 3W 28i here on RCU. After doing a search, there really isn’t much info here on RCU about the engine. It would be great to hear from those who have some experience with the motor about such things as prop size, RPM’s, any gotcha’s etc.

The motor I purchased came with a header and can, any suggestions on a side dump muffler.

Thanks

Tired Old Man

My Feedback: (1)

16-16 tp 20-6 propeller. Best prop for most apps is around 18-6 to 18-8. The engine normally develops around 1300 watts when set up reasonably well, and it's still the benchmark for power with engines in it's class. Aircraft International handles parts for the engine here in the U.S., including muffs.

If you don't hit the ground with it and take reasonable care it should last 700-900+ hours of running time. I still haven't come up with a max life cycle yet because when using the right oils and ratios i haven't been able to wear one out. It likes a 50-1 mix of a good oil. It has shown a particular fondness for Stihl HP Ultra, which is how those high times have been derived. Torque specs for just aboot every screw on the engine is 35 inch pounds.

You don't see much about them because they cost more than people want to pay. Reality is they cost less since they last as long as a Zenoah when halfway cared for. It's a superior engine for people that take their hobby seriously.

aussiesteve

I just can't resist even though I have little to add to T.O.M.s post.

See my signature line?
The 3W 28i was the engine that prompted me to use it initially. I tried many other lesser products before I asked a a "Wise Old Man" for his suggestion on a decent product. Cost was not an issue, reliability and performance were everything. (he has also since pointed me in the direction of a couple of other top of the range products that reinforced my sig line).

The reason you see very little posted about these engines is
1- As T.O.M. mentioned They cost a bit more to purchase than most wish to pay - it is a good investment though.
2 - As also mentioned previously, provided you don't kiss the ground with them, they simply work well and go on working well.
3 - Those converts who do get it and fly them are too busy enjoying their flying to be chasing info on line

I have a couple of them now, I have a 20/6 on one (a slow light scratch built fun flyer) and an 18/10 Biela on another that is regularly flown on a small Extra. I tend to run in new ones on an 18/8 for most purposes.

PM me if you are looking for easy ways to set the engine up in the plane, I will send you some photos of how I fit them.

helodrvr

My Feedback: (88)

Thanks T.O.M and aussiesteve for the input. From what little information I found on the motor, all pointed to a great little motor, so I am sure I want be disappointed. As for the initial price, it is a little steep, but with a little patience I was able to pick one up here on RCU for good price.

T.O.M: In some post made by you several years ago about this engine, you mentioned some simple performance mods that can be made. Can you give a little more detail? And yes, my favorite flavor of oil is the Stihl HP Ultra, so me and this little engine shall get along nicely.

aussiesteve: How do you like the 20X6? This engine is going in a wild hare 30cc edge (have to make some minor mods to fit the can) so most of my flying will be 3D stuff.

Again, thanks guys for the input.

Tired Old Man

My Feedback: (1)

The greatest performance mod you'll make with the engine is to do away with the ignition. It WILL fail eventually. Only the when is in question. So pick up something as a spare for when it happens.

They handle a little added back pressure quite well so a tuned pipe is a good investment for those that like to experiment. The 3w cannister is a perfect match for the engine so a little upwards power bump is not unusual.

For best performance, and for most they would never notice the difference, measure the squish band. Right around .024" is ideal but don't go much below .022". They can be quite effective up to about .030 but some RPM is lost at that point. You can order different thickness base gaskets, but you have to ask for them

Whatever muffler you use, match it to the exhaust port. The 28i really doesn't like interference at the port flanges.

Pull the intake manifold and check the reed seating. The engine has a rather unusual reed cage and it has to be kind of "pre-loaded" when it's fit with the reeds to the case. Easy to hang a reed open although it doesn't seem to make a lot of difference unless they are hung open quite a lot.

Gap the plug .018" to .020" to make life easier on that ignition, and pay attention to the stated ignition voltage. 3W ignitions can be quite finicky about their input voltage. Make sure the ignition has a cooling air flow to and around it.

Change the ring when it develops an end gap of .016". Book says .018" but they get unreliable on the low end at that point. They'll run wot all day without a hiccup but the throttle down and back up can become dicey. Minimum end gap should be around .004"-.006". You don't need a Bowman ring. 3w knows how to make a good cylinder and ring.

Premium gas, only and forever. That's true with every 3w engine. They WILL detonate with regular grade unleaded gas. No need for avgas, the engine doesn't like lead either.

After a whole lot of the darned things I think I've just about got 'em figured out except for one thing. I really don't know what their maximum life span is because I haven't been able to wear one out under "normal" or slightly above normal use conditions. Worn out a lot of rings but no cylinders or bottom ends yet.

helodrvr

My Feedback: (88)

T.O.M. that is a lot of great information and I do appreciate you sharing it. This motor should be a fun one.

Thanks

aussiesteve

T.O.M gets to "play" with these engines (more than just a couple of them) on a very regular basis - follow his advice. There would be very few on the planet who know them better.

For the 20/6 prop. I don't think it would be the best choice for you. More than likely an 18/8 or 19/6 would be a better choice for your purposes.

Tired Old Man

My Feedback: (1)

thousands?

aussiesteve

I know - I saw the photos - kinda made me jealous

Best single discovery I ever had in this hobby was following your advice to these engines (and a few other particular brands). Now the only reason I touch my planes in the shop is due to my own "psyhco-motor failings" (aka Dumb Thumbs), routine checkups or new builds because I am bored with the existing landscape in the shop.

Tired Old Man

My Feedback: (1)

Thanks for the flowers buddy

No intent to trash other product lines but you have to admit, it's nice being able to fly and forget about an engine because you know it was right today, yesterday, and will be the same tomorrow. I really hate having to constantly fuss over an engine, and doing it all day, every day, at work makes it even worse when it comes to your own. Ask Jody how much I bother with my own now. I get so overwhelmed with the stuff I'll settle for so-so tuning on my personal engines but everyone elses will have to be dead on. A real good engine provides for a lot of latitude in operations.

So a good engine that makes plenty of poer, high reliability, and equally reliable engine accessories is all I'll have anymore. It actually provided more real flying time once that choice was made.

rc bugman

My Feedback: (30)

T.O.M

I am still trying to wear out the 3w-24s. I thought that I would wear them out before moving up to the 3W-28. Guess I will have to wait longer..

Elson

Tired Old Man

My Feedback: (1)

From what I've seen you still have a ways to go. That's another "timeless" engine and in my book the best 3w ever made. The 28i was, IMO, a downgrade from that one.