Luxuswaffe

MVVS .61 (10 ccm) at 8,370 rpm with box muffler swinging an APC 13x9 prop on the ground. Brand new engine.

MatheusC20XE

nice airplane..

I think with a 11x7 prop this engine will turn much more...

rainedave

My Feedback: (1)

Nice looking plane. With a cowled engine running with that much prop load you might have overheating problems if you set it too lean.

David

Hobbsy

My Feedback: (102)

An 11x7 is much too small, here is the official prop recommendation from MVVS. My MVVS .61 is converted to Diesel and turns an APC 14x7 at 9,500 rpm.

props: 15x6, 14x6, 14x7, 14x8, 13x7, 13x9 for glow operation.

Sport_Pilot

I bet it would turn a 12-7 well. I really don't think I would be scared of the RPM or ruining the engine.

Hobbsy

My Feedback: (102)

How are you Hugh, the MVVS .61 is a long stroke engine designed to turn in the mid nines. I have one and it is perfectly happy doing so.

Luxuswaffe

Pe Reivers recommended this prop/pitch size. The box muffler is taking some rpms away. It is a very strong engine though and has little work to pull this 6 lb war bird through the sky. I'll try other props as well.

Hobbsy

My Feedback: (102)

Lux, that box muffler is a marvel of simplicity, for a simple empty box it has a nice sound, I run one on a Fox .74 and it is perfect for it.

Luxuswaffe

Sound wise I agree with you. Sounds like a 4-stroke. 8-)

DarZeelon

The MVVS came out with low noise and RPM in mind.

It does have the the 'Long Stroke' era bore and stroke dimensions, of 23 and 24 mm respectively.


In two independent engine reviews, this engine (RCM - Clarence Lee review) spun a 14x6 prop, more than 2,000 RPM faster than an OS.61FX!

Its advantage grew smaller with lighter props, until they were about equal with an 11x6.


Curt (RaceCity) has one with the MVVS #3250 pipe and it spins a 13x8, or 9 APC at over 10,700 RPM...

This is a very respectable achievement, for an engine intended for low RPM, with a 15 mm O/d crankshaft.

Luxuswaffe

I made a little video on those who are interested. You can view it here:

http://rcuvideos.com/video/MVVS610001-wmv

Turning an APC 12x10 with the box muffler at 8700 rpm max. The APC 13x9 made a 8400 rpm. Maybe I should go to a larger prop with less pitch to obtain more rounds. But then my flying speed will fall behind. I am not a 3-D enthusiast.

DarZeelon

Luxus,


Your engine displays a wonderful idle, but on the top it seems to be an underachiever...

The #3298/10 muffler does fit in small places, but it possibly curtails the power drastically.


There is absolutely no reason your engine would not spin these props, about 2,000 RPM higher with a tuned exhaust, or 1,000 more with other normal mufflers.


Can you tell me how you did the break-in?
My method is [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]detailed here[/link].

Luxuswaffe

Hello Dar:

Thanks for your ongoing replies. I have run the engine in as to the manual supplied by MVVS.
Except: I have run the engine in mounted on the plane.

Fuel is Omega FAI fuel with 0% Nitro, 17% lubricants and I added 8 US tablespoons of pure castor to the US gallon to make good for the remaining 3% lube.

DarZeelon

Luxus,


I find the MVVS break-in rocedure a bit lacking.

Nevertheless, your engine should be in a condition to make full power.
See what you can do about the exhaust...


This 'dustbin' must be choking it...