MW Engines from Italy - Question

N962GT

Active Member
Joined
Oct 25, 2020
Messages
134
Location
orig Northville, Mich
Aircraft
YG4 Air Command Tandem
Total Flight Time
800 hrs
Someone posted some photos of a gyro build using an Italian MW experimental aircraft engine. Unfamiliar with these motors, looked up the web site and sorted out the engine specs, discovered something I don't understand. Maybe someone can explain it for me: How do you get a 15% increase in power with the same engine, same displacement, RPM, compression, engine weight, valve train (?), intake/exhaust (?), same fuel burn...

In both cases the TBO is 2000 hrs for the weaker version vs. and 1800 hrs for the stronger one.

Anyone know anything about these engines? Cost? No prices listed.

The direct-drive 100 HP/ 3400 looks terrible on paper. Engine weight is 180lbs, and since typical gyro prop efficiency drops off after 2900-3100 PRPM, at that ERPM the power is probably only about 80HP. This doesn't add up to very good thrust in flight.

The next step up engines look a little better, but now it grows to 190LBs for 122 HP and the prop only turns 1965 PRPM calculated at peak power - FAR less than what you need on a gyro, which needs to be minimum 2400 PRPM for best flight thrust. MW lists 2450 as the PRPM, but I don't see how that is even possible given the info listed. Next, 4.9 GPH is at least 20% too high compared to other engines at similar output.

The sister engine to that one shows 135 HP and a much better gear ratio which does a much better job at lining up minimum PRPM with peak power, though that is still a bit low if you're running anything under 72" prop diameter.

Next upgrade is the Sky Line 140. I'm finding the engine weights a bit suspect as they bump up to 300cc added displacement but not even one ounce difference in reported weights. Again, final ratios produce a range that is great for big tractor FW props over 74", but 500 PRPM too low for typically smaller gyro props' best efficiency range.

The 140's sister engine, Red Line 160 raises eyebrows. The only thing I know of that can compete with this engine in this weight class would be the Yamaha EXUP which has been out of production for 4 years <sigh>. Comparing the two is still interesting. The EXUP weighs 165 lbs and puts out 165 HP, with cruise burn at 4.5 GPH. Compare to MW claimed at 190 lbs., 160 HP and 5.1 GPH. If the gear ratios were a bit shorter on the MW I'd really
like this engine on a gyro. But, again, it's geared for swinging a big FW tractor prop, not a 68" - 72" pusher prop.

Oh, well.
MW Engines, Specs.png
 
Top