How is this engine? Does anyboby have it? How does it swing 15" and 16" prop? Throttle response? Thanks!

seanychen,

I was hoping you would get some good responses to this question. Nobody has responded yet so I'll chime in and tell you why I just purchased an MVVS .91

1) The price is right. I ordered mine from Just Engines in GB and after shipping charges, the price was $157 and change.

2) True ABC piston/cyl and not a ringed motor.

3) Is not considered a "long stroke" motor therefore should like to rev higher than other .91s.

I haven't run mine yet so I cannot give you any figures or even impressions as to how this motor runs but I am willing to bet $1 that it is at least as powerful, if not more so, than the OS .91 FX.

I could be wrong but because it is a short stroke, I think 15 and 16 inch props would be a bit much. I will stay below 14" dia with mine. In fact, I intend to put it on a racer so I'll put a 12" or even an 11" prop on it and really let it spin.

Jaka, can you respond and give us your thoughts on this motor?

Thanks!

I would like to run the APC 15x4W prop, which is about the same load as the 14x6, but a little heavier which may delay the spool-up.

Hello!
The MVVS 15cc engine is delivered with the new No 3222 (10mm intake butterfly valve) carb and this carb gives very good throttle respons, much better than the old old drum valve carb (8mm) of the past.
The engine is a ABC engine with dubble ballbearings with a split crankcase which enables you to choose either a rearexhaust or sideexhaust configuration.
The engine is not considered a "long-stroke" but it could still cope with larger propellers.
I have run it in a "Diablotin" 3D model with both a APC 14x4W, 14x5N , 15x4W and 15x6 props. Best of these props for hovering is the APC 14x5N.
With the super-quite MVVS silencer (No 3255A) itīs much quiter than any fourstoke.
Iīve use 15% oil! (Motul "Micro" all syntetic oil and the Graupner line of all syntetic oils : Aerosynt 2 and Aerosave) and 5% nitro.
This is what many flyers in Sweden use (and Europe).
Castor oil is a thing of the past!!!!!!!!
Glowplug: MVVS as supplied with the engine or a Enya 3 or OS 8.

Regards!
Jan K
Sweden
http://hem.passagen.se/airracing

Hi Jan

How does the .91 compare with it's obvious competitor, the OS .91 FX, for power and general ease of handling?

Your thoughts would be much appreciated.

Regards

fiery

Hello!
The OS line of engines are first class and though MVVS make good engines too they do not reach OS high level of manufacturing refinement and easy handling qualities that is the trademak of every OS engine. The MVVS is also very easy to adjust but the 15cc engine does have a little more tuchy idle needle. You have to losen a screw and then turn a small exenterscrew and then set the first screw again. A little more cumbersome than on the OS.
But after you set the needles on the MVVS itīs a very reliable performer capeable of slightly lower idle rpm than the OS.
It also performs perfectly on 0-5% nitro.

For a modeler with a few years experience though I would say itīs a toss ............, regarding starting , throttle adjusting, idle adjusting and all out handling qualities....but for a total novice ...The OS has the edge....But on the other hand.....a total novice should not get such a big engine in the first place.
The MVVS is quieter though than the OS and you have the possibillity of changing the muffler to a minipipe for added power.
I would also think that the MVVS is a lot cheaper.

Regards!
Jan K
Sweden

Hi jaka, how does the MVVS .91 compare to the OS.91FX in weight? I cannot seem to find the specs on MVVS Engines.

Johnny, according to the MVVS factory site the 15ccm is 552 grams or about 19 and 1/2 oz, almost the same exact specs as the OS 91FX without muffler.

I own an MVVS 91, and it's a real stump puller, especially with the mini-tuned pipe I picked up with the engine at Morris Hobbies. Don't have a OS 91FX to do a direct comparison, but a good flying buddy does and they seem equal in power pulling our 60 sized aerobats around. Difference is I'm running FAI in my MVVS and he's burning 20% nitro in his OS. I've put an APC 15x6 on the engine which it spun without issue. I know some 91 2C have problems spinning large diameter props...

As mentioned before the MVVS is an ABC engine unlike the ringed OS 91FX. They break in differently. Mine was good to fly after three 8 oz tanks run through it on the ground, while my friend needed to put almost half a gallon before he put his FX in the air...

Hello!
As f2racer says the MVVS 15cc (.91) weights 550g and the super quiet silencer weights 100g.
I have some if you are interested?

Regards!
Jan K
Sweden
[email protected]

f2racer, thanks for the specs. I've got several MVVS engines (2-.49's and a .77 all w/ silencers) and could'nt be any happier . Got a Diablotin Super FG lined up that I was gonna to use the .77 w/mini-tnd slncr. on, but I'm thinking the .91 would be a better 3D choice. Have you, by any chance, tried an APC 16x4W on your .91?

jaka, thanks for your reply. Which would you suggest for the Diablotin Super FG.


P.S. Love those tuned silencers!!!! (they should all look that cool)