Interesting that it has conrod bearings at both ends, I should have paid closer attention, thought it was referring to the crankshaft. Then it means this engine is a real jewel. Glad to see the production model is already improved over the prototype.

They hadn't updated the instruction manual for the engine at its time of release, but there is a needle bearing on the big end of the rod now. For production they had the needle bearing put in. The earlier prototype engines had a bushing on the rod though.

The problem is no one really knows what using a reduced oil ratio would do to the engine if anything. So they are being conservative on the suggested fuel/oil ratio needed with the engine. It may very well work with less oil in the fuel, but no one really knows for sure yet. One issue is as the engine gets smaller and smaller it needs more and more oil in the fuel to stay properly lubricated.

I would suggest using the factory suggested oil ratios for now. After breaking in the engine really good, then after you have a extra set of parts on hand for rebuilding the engine, you can try running less oil in the fuel and see how well it holds up. I can see going from 20:1 ratio down to a 25:1, but it is iffy if a 32:1 ratio would work Ok or not. I just would not try it unless I had spare parts on hand. But as many more people get the engines and use them, we will start to see some trends develop. Using a high quality synthetic oil may let you reduce the oil ratio needed versus using low grade mineral oil stuff.

if ylou think about it, we really haven't had any small production gasoline engines made and being used since before World War II. There aren't a lot of people left from that time era either. So we are sort of having to re-invent the whole thing nowadays. also way back then the quality of the oils wasn't very good and we have much better oils available to us today. They used to use SAE 70 and 80 weight mineral oils in the old days. we now have some really good synthetic oils available to us today. Plus the modern engine designs are much more modern with ABC cylinder pistons, better metalurgy, higher precision machining, ball bearings and needle bearings, electronic ignition and so on.

I would suggest using a really high quality synthetic oil in the engines so as to reduce the carbon buildup that occurs using mineral oils. Since the engine is smaller, the carbon buildup will be more pronounced in it as compared to a larger engine. The little spark plug could foul out a little faster with lower grade oils.

Appreciate the advice, will keep in mind when I procure one. Have never been one to abuse engines, keep them for a long time. As I mentioned before, this engine definitely has caught my attention.

I have two waiting for pickup ay my LHS, my friend got his last week and has already flown it several times in a 60 size sport plane. He is very happy with how it starts and runs and we will keep a close watch on how they perfrom and last from use. Since winter has just set in mine will have to wait until spring for flight reports.

If it has full roller and needle bearings then could it be the ABC design that requires 20:1 oil mix? Perhaps a ringed design would have been better in that regard?

We tried a ringed design early on and lost too much power when compared to the ABC construction. As I've mentioned before we will be doing more testing with lower oil quantities but as of right now we don't have enough data to definitively say it is safe to use a lower oil content. As that data is collected we will pass on the info.

Pete
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Thanks Pete, and it definitely does have needle bearings on both ends of the rod?

Needle bearing on the bottom end bushing on the top end.

Happy new year guys, I have a blackhorse Aerocommander Shrike sitting in my shed waiting for a 9-10cc gas engine. I had my hopes pinned on the NHG 9cc but it looks to be having some issues.so far all reports on this engine have been positive so im very interested .Two questions, first on the muffler- will there be an inverted pitts muffler that will fit this engine.the supplied muffler looks way to big to fit in a cowl. second quesiton is when might we see this engine in Australia.thanks

The Evolution 10cc gas engine uses an amazingly common muffler size. So you can pretty much get most everything to fit OK for a muffler.
From the Mac's Muffler website a list of mufflers that would fit OK. Thus choosing a Pitts muffler should not be a problem. I would likely go with something that would with the OS .46 through .55AX engines though.
Of course the Evolution Pitts muffler would work too http://www.horizonhobby.com/products...GX#t4-OPTIONAL

OS.40-.46 FX,SF, .46-.55 AX, .50 SX
-( also see the new .55 AX muffler #6720 )-
Evolution .40NT &amp; .46NT-NX &amp; Trainer A
ASP .46, GMS 2000 .40-.47
Irvine .40 &amp; .46 (bolt through)
Magnum XLS.46
MECOA .40-.46, Royal .46
MDS .48 FS Pro (bolt through)
Rossi .45 (new)
Thunder Tiger .40 &amp; .46 Pro
(center to center = 37.08mm/1.460")

or even these too:

O.S. .46-.55 AX, .50 SX (bolt through)
-(this muffler is a better volume match for the
.55AX, .50SX and the .46AX than the #6590)-
ASP .52 Evolution .52-.60NX
Magnum .52 XLS
Rossi .53 (new)
Y.S. .56 SR (new)
(center to center = 37.08mm/1.460")

inexpensive!

- carburetor $50
- conrod + piston $60
- spark plug $13
- ignition unit $70

the new OS 15cc do have roller berings on both ends....

That OS con rod is a beauty. Do you have a link for viewing the whole engine? Thanks. Their 22cc is the newest one I've seen.

thanks earlwb, i wasnt aware that the muffler size was so common. now to find out where i can get one.Horzion wont $153.00 postage to australia- ouch

Yeah,, I think that if you were going to try out a lower oil to fuel ratio, then the parts of interest are the Cylinder, piston and ring, wrist pin keepers, rod and maybe the crankshaft.
The crank is included should the big end needle bearings gall the crankpin.
That is just in case you prematurely wear something out. Of course you may not need them if it is successful.
Cylinder piston set $30.00
Connecting Rod $30.00
crankshaft $33.00
and a gasket set $0.47

Of course one could just buy another new engine instead of repairing it.

If the engine slings a rod there would be little left that was useful.

I got the impression from reading the manual that the muffler size and shape was an integral design component to maintain a user friendly engine. It might not be a good a idea to just throw another muffler on that bolts up. It may create tuning issues for you.

Well did some more searching and as far as I can tell, no OS yet, and the only OS is still for Heli use. If you look at the pictures you can not put a prop on this bad boy. The engine that's supposed to go to market has changed a little from the concept engine. The carburetor hangs out past the drive washer, but this is intended for Heli use.

Considering the GT22 is priced at 409.00 you would have to imagine this one being in the upper 300.00 price range.

http://translate.google.com/translat...jp%2F121213%2F

http://www.os-engines.co.jp/english/...newsgt15_e.pdf

The Evolution will more than likely a better choice for most modelers based on OS's pricing history.

That's a 15cc heli engine. Where's the engine for an airplane.

Yep! That's what I said in the post, it's a Heli engine and can't find any sign of an airplane engine!

With Pete Bergstrom, manufacturer representative's inputs it seems a small price to pay for using the recommended 1:20 oil to gas ratio. Cleaning spooge off a nitro plane 2 cycle engine is normal practice. So is living with a little 2 cycle oil spooge, too. Thanks for others pointing out that the upper conrod is bushed. With this engine being at half the price of its counterpart's typical pricing and priced around the cost of a 4 cycle glow engine should make it a popular choice.

I don't know about others but I usually clean off a lot of bugs and grass clippings, so some residue won't kill me. It's not like glow fuel at 5:1 that looks like you just dumped oil all over your plane.

As for the rod bearings, the lower end takes more abuse and actually makes full revolutions. The upper end is a pivet point and does not have as much movement so the bushing should not be a problem.

You got some valid points there, AJsToyz. I'm used to cleaning glow glop so reduced residue would actually be welcomed. Also thanks for pointing out the bushed upper just rocks through what? less than 45 degrees back and forth? I'd think still the 1:20 oil to fuel would guarantee sustained engine life until the facts are in that lower oil content is determined adequate.

I almost forgot about it, but some mufflers may not have much restrictions inside so that it develops some good muffler pressure. I remember some guys having problems with certain Pitts mufflers with glow engines before. This was on engines that had too large of a bore carburetor on them thus making the engines more sensitive to being able to draw fuel OK.  So it may be worth keeping that in mind if they run different mufflers or Pitts type mufflers on the Evolution 10cc engines.  The common fix was to restrict the muffler outlet or outlets some more, which increased the back pressure giving more muffler pressure.

Engines can loose or gain power changing the muffler. I just wonder if you would loose power going to a small Pitts style muffler considering how large this muffler is.