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MVVS 26IFS Power Question

Old 04-04-2006, 12:39 PM
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Default MVVS 26IFS Power Question

I have some questions about the performance of my MVVS26 IFS gasser. I have been breaking in the first of two engines for use on my OV10 Bronco. I love everything about the engine so far.

I am about finished breaking the first engine in on our 82 octane gas with a 30-1 mixe of Amsoil Dominator oil using a barrowed 3270 MVVS muffler. It has a gallon through the engine to date. I am running an APC 17/8 prop and have been getting about 6900 rpm with the high speed needle set at about 1/4 turn rich. There is always a little oil on the airframe when I finish the flight. This morning I switched props to test my Mejlik 16/11 three blade prop that I plan to use on the Bronco and had to richen the high speed needle another 1/4 turn to get it to run full throttle in the air. This was the first time this engine has quit in the air since I started the breakin period. It is only tacking at about 6150 rpm. It did not seem to pull as well as the APC at 6900 rpm.

Is this acceptable performance and is there anything I need to do to improve? On a twin I want reliability over getting the last bit of power but don't want to take any chances on under powering the airplane.
Old 04-04-2006, 02:24 PM
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Default RE: MVVS 26IFS Power Question

Gaines,


The benchmark RPM for this engine, with the #3270 silencer is with the 18x8 2B Mejzlik (pronounced Ma-i-sh-lik) prop, 7,300 RPM.

A 16x12 2B would give about the same load. A 16x11 3B is heavier, but I believe the RPM should be somewhat better, as it should have been with the 17x8 (significantly).

Let us see what PĂ©, who has more experience with the gassers have to say.
Old 04-07-2006, 05:08 PM
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Default RE: MVVS 26IFS Power Question

The engine quitting, is a sign of being lean.
What do you mean by 1/4 turn rich?
Turn out the High speed needle, until the engine starts burbling, then lean out until peak rpm. Back off the needle again until rpm just drop.
With a tuned pipe, I get in excess of 8100 rpm on APC 18x8N, so you should see about 7400 rpm or better on the 17x8 and 3270, so it seems you have the engine off tune on the lean side. Oil specs on the airframe are no indication to go by.
For carb tuning, see [link=http://prme.nl/forum/viewtopic.php?t=10]http://prme.nl/forum/viewtopic.php?t=10 [/link]
Old 04-17-2006, 06:02 PM
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Default RE: MVVS 26IFS Power Question

Well, I finally had some time to follow Pe's instructions on setting the carb on my MVVS 26IFS. And guess what, he was right. I had somehow really got the carb out of whack. Following his instructions I am now getting an easy 8300-8400 RPM on the APC 17X8 prop. Transition is good and the color of the plug is about right. Maybe just a little on the dark side of the tan color Pe recommends.

Thanks.

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