I have a brand new MVVS 91 with a 3255 silencer. I plan on running 5% Cool Power. I am at 30ft ASL. Prop will be APC 16x6. What RPM would I expect this engine to swing the prop at once it's completely broken in?

RAMZ,


DON'T YOU DARE EVER TRY RUNNING 'CRUEL POWER', OR ANY OTHER ALL SYNTHETIC IN YOUR MVVS.


Your engine needs fuel with 20% oil, at least half of which is Castor.

There are commercially available fuels that have this oil content; PowerMaster GMA and Sig Champion, for example.


If you use the 'fuel' you intended to, you may not immediately ruin your engine, but it will run very badly and you will void the warranty and you will never be able to hide this.

...Your plane will stay clean...


Do the break-in as described in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this RCU thread[/link] (you will be adding some degummed Castor to the oil package).


I cannot give you an exact number, but you would expect 8,000-8,500 with this prop. It is pretty large in the usable prop range for this engine. The 15x6 size is more appropriate, I believe.
The #3255A silencer will not reduce the RPM by very much in this low range.

If this prop reduces RPM considerably, it places the engine below it peak torque and this can cause overheating.

wow...i had no idea cool power was so bad for this engine. Thanks for the advice. I'll make sure i get some castor based fuel.

For break in, I would reccomend a 14x6 with the 3255 exhaust and I echo Dar's concerns about fuel...use the pink stuff!!