Last week we had very nice weather, so on Friday I took the afternoon off and went flying. I had put the 3M-170 into the Evolis with the same muffler (Greve) at same length as I use on both the OS and 3M 140. As mentioned below the RPM was a little less than expected during static testing with a too long header. Now, with the correct length it all came together to deliver very good performance. Measured at ground with APC-17x13 it turned a solid 7600 RPM ! This is about 3-400 more than the 140'th which may not sound like a lot, but you need a lot of more power to do this. In the air, the Evolis felt very powerful. Pictures below.
News, January 2003
Received a new 3M engine last week, the new 170. They have made a new cylinder with a bigger bore (35mm), the crankcase seems to be the same. I put it on my test-stand and ran it for a while during the weekend. It ran super smooth with good power. With the supplied carbon tuned-pipe it turned 7600 RPM with an APC 17x13 and my regular fuel with 15% Nitro and 15% oil. The header did not make the proper system-length with Greve muffler that I usually fly with, so I have to get back to that setup later. 3M suggested two OS A5 plugs, I did not find the idle and transition to be as wanted with this so I swapped one of them with an old OS-F; excellent !
Some pictures of course :
For the 2002 season I plan to use the Italian made engine 3M-Mintor. I received it on Saturday the 23. February. I have not been able to test it yet (testing will first be static, my Evolis XXL is not ready yet, and there is winter in Norway). The engine is completely CNC-milled from bar-stock, compatible in mounting dimensions to the OS140RX and very light at 760g. The price of the engine is very competitive. Here are some pictures I have taken of it.
I recently received an e-mail from the manufacturer, with a link to their WEB-site. It's : www.mintor3m.it
Flight-test (12 May 2002) : Finally i was able to complete and test the new model (Evolis XXL) with the 3M-engine inside. I used a Mac's header (for OS 140), a Greve competition muffler, APC 17x13 and fuel with 15% Nitro and 15%Aerosynth-2 oil. With idle adjustment in neutral position it ran beautifully with excellent transition, good braking and competitive power. Actually it behaved very similar to my OS's.
Static testing (2 March 2002) :
Did some static testing yesterday. Ran it with APC 16x14, my standard fuel (15% Aerosynth-2 & 15% Nitro) and a Greve competition muffler. It was around 0°C so I did not care to do testing with other propellers (it was damned cold in the propblast). Ran it alternating rich and normal for about 1 liter of fuel. Had the tachometer around and saw 7500 at one point. It started relatively easy (remember 0°C), transition was good and steady idle below 2500. Nothing special, as expected. I think this engine will be a smooth and powerful friend during the upcoming season.