670 & 277 Engine

Rich Gillen

Is this what you have? Which Model A, B, C? The last model made the 180 C model has a MTOW of 512 lbs = 232.2393 kg / 10 kg = 23.22393 kw needed = 31.1438 hp needed. It was 262 lbs with a Single Carb 503, and carried 7 Gallons, so it didn't make Part 103 with a 503. A purpose built 277UL, 377UL, 447UL or Kawasaki 340, 440, would have been better Engine Choices.

Rotax puts out a Fuel Consumption Graph in there different Manuals. As I showed you at 6000rpm where it actually made Max 25.4hp@6000rpm on the Dyno. It works out to (0.134) for gph for the 277. Each Plane & Pilot Weighs are different and has different Drag.

277UL using Rotax graph. All GPH Approximate's off Graph. Each Engine will be a little different.

6500rpm = 4.1 gph 20.5hp -2.8hp           
6250rpm = ?.? gph 23.3hp -2.1hp
6000rpm = 3.4 gph 25.4hp  <--- At 6000rpm is where it made Max 25.4hp. 3.4 / 25.4 = (0.134).
5500rpm = 2.7 gph 23.2hp x 0.134 = 3.1088‬
5000rpm = 2.0 gph 17.9hp x 0.134 = 2.3986 (2.4) gph
4500rpm = 1.4 gph 12.3hp x 0.134 = 1.6482 (1.6) gph
4000rpm = 1.0 gph 10.1hp x 0.134 = 1.3534‬ (1.4) gph.

The Lazair Ultralight flew on 11 hp very Marginally. Was soon upgraded to 18.8hp, and people still wanted more hp. If you run the Lazair Numbers MTOW: 450 lbs = 204.1166 kg / 10 kg = 20.41166‬ kw needed = 27.37249 (27 hp) needed! The Solo 210 15hp each was the ideal setup. Today a pair of these Honda/Clone GX200's 4 Strokes Singles built for 15hp@5000rpm each is the ideal setup.

Stock Rotax 277UL Dyno Numbers with Rotax Exhaust. You will notice it was Avg +2.8hp per each +250rpm. It starts losing Power after 5500rpm. It's probably Rotax's Muffler is too Restrictive. More Prop rpm means more Thrust made. If your 277 Engine kept making +2.8hp per each +250rpm like it should at 6500rpm it would be making around 34hp!

So learn what you can do to make your Engine more efficient. Example: A 377UL is 35hp@6500rpm. The 377F/380F in a Sled is 36hp@7000rpm. A Stock 380HO is 48hp@7000rpm. A stock 380HO with an aftermarket Tuned Pipe Dynoed 57.26hp@7000rpm. It made 52-53hp@6500rpm. A 377F/380F/380HO is 368.4cc/7cc = 52.6hp@6500rpm!

Ecotrons EFI.

Magasquirt EFI Open Source, you can build your own ECU.

Cylinder & Case Porting alone can Gain you 10-15% more Power. This guy is Good and also does the Engine Coatings.

Using Rotax Spec's and if Ported:

277 26hp +10% = 28.6 hp

377 35hp +10% = 38.5 hp

447 40hp +10% = 44.0 hp

503 50hp +10% = 55.0 hp

582 65hp +10% = 71.5 hp

The #1 Single in the World today is the Simonini Victor 1 Super, 400cc, 54hp@6500rpm using 9.5cr, 34mm Carb, with a Tuned Pipe. 70 lbs Complete.  Same Engine just different Bore & Stroke, 362cc = 44hp, 382cc = 48hp. The 400cc/7cc = 57.1hp - 2hp = 55.1hp for the 9.5cr vs 11.5cr is about as Perfect as you can get.

Re: 670 & 277 engine
From: John Hoxie
Date: Wed, 06 May 2020 17:12:09 PDT


thanks for all the info. I didn't realize for Rotax you multiply the hp by .1 to get fuel burn. I'm hoping on my Kasperwing for slow cruise at 4000 RPM. It won't be flying for at least six weeks. Is that true for the 918 and such also?