I need some help to break-in my MVVS 40 Quickie and to make the tuning of the mini-pipe which comes with it (N° 3246).
As it is an ABC engine, I think first : to make the break in as described by Jett engines. The manual from MVVS is very short: two lines for break-in!
After the break-in I need to adjust the lenght of the pipe to have a tuned mini-pipe. How do you suggest me to do this tuning?
The only propeller in the french Q500 rules is the APC 9x6.
With my thanks for any help.
Claude

Claude,


I wrote [link=http://www.rcuniverse.com/forum/m_1850473/anchors_1850473/mpage_1/key_Tapered%252Dbore%252Cbreak%252Din/anchor/tm.htm#1850473]this thread[/link], about break-in, which from my POV it is a bit more precise and detailed.

It also gives a better explanation about all the 'why's.

Follow it! You can easily do it with the #3246 tuned silencer and use a 9x6 APC, which can be cut down a bit, at the tips, to 8.5x6.

Don't use a Master Airscrew prop. The RPM limit for this size is exceeded by this engine.

Thank you very much Dar for your comments and great thread about break-in ABC engines.
I will follow your advices.
If you have any suggestions about the "length tuning" of the mini-pipe, I am interested.
Claude.

Claude,


Using the system 'as is', with the header and tuned silencer separated by 2-3 mm, will support this prop size very well, showing 17,700-18,200 RPM.

If you want tor use a larger prop; 10x6, you would have to extend the system, with 30-40 mm between the header and silencer. You would not want anything larger than 10x6 on this engine.

The exhaust can be tuned shorter too (cutting the header 10-20 mm), for props that would spin up to 23,000 RPM.


Don't expect this engine (or any other MVVS) to show its maximum performance, until it has run 5-8 hours beyond the break-in. I have seen a 600 RPM gain within this amount of run-time.

Dar,
Thank for the comment, I will use header and mini-pipe at their actual length.
Why it is so long to obtain the maximum rpm on MVVS enginses ( 5 or 8 hours )?
Claude.

Claude,


The engine will be completely usable after just 2-3 (20-30) tanks of fuel.
However, for the very tough, high quality materials, MVVS engines are made from, it takes a little longer to achieve perfect fit.

If you own a car made by Peugeot (and other prominent companies. I have a 406 2.0L), you would notice it takes a lot more than just the break-in period, for the engine to reach 'maturity'.
My car took about 30,000 km, to cut 0.4 seconds from the 0-100 time, compared to the number at 1,000 km.

It still shows the same numbers with 100,000 km.


Your MVVS engine will take time to reach its full performance, but will hold it for about 100 hours of running (if not abused).

Some less expensive and common engines are made of 'softer' materials, to reach maturity ASAP... No one cares if they only last 15-20 hour afterward, as replacement is preferred to repair, with very high part costs.

MVVS parts are not expensive, since repair is the cost efficient way to keep your engine running at its best; not throwing it in the garbage and buying a new one...

Enjoy your MVVS!

Dar,
Yes I have a Peugeot, an older one than yours: 405 break with 200 000km. but I don't make drag racing (0-100 time) with it! What is your time for the quarter mile?
I will be happy if I could make 100 hours of flight time with my MVVS, but in pylon racing there are midairs with others or with ground at high speed.
Do you think I could make the break-in even if the outside air is between 5 and 10°C? How to choke the engine without turning the propeller when the engine is cold?
Thanks for all.
Claude.

Claude,


There is absolutely no doubt in my mind, about the possibility to perform the break-in, at 5-10° C.

You can prime the engine by raising the piston to mask the exhaust port (turn the propeller a bit) and blowing into the silencer.

The pressure created in the silencer and in the fuel tank, pushes fuel into the carburettor.


I never measured the 1/4-mile, as there is no drag-strip in this country; just 0-100 kph...
It is not a drag race car, but my family car and it is even automatic.

Here, this model is considered an executive car was never sold with a standard shift gearbox.