Specific Fuel Consumption
 

What is the BSFC of a Lycoming or Continental engine?

Just for comparison, my V8 is between .40 and .50, with an average burn of .45.

Here are the latest numbers from the dyno runs...

4000 rpm:
24 inches = 345tq 260hp 19.5 gph
22 inches = 324tq 246hp 18.7 gph
21 inches = 303tq 235hp 16.2 gph

3500 rpm:
24 inches = 335tq 220hp 16.5 gph

From 4000 to 3500 the torque values are about the same but the hp drops about 40.

This comes in right at .45 lbs / hp / hr. Right on schedule for a high performance V8.

The IO-550 line gets around .37-.38 LOP at 75%

What is the hp/torque at 75% power? RPM / Manifold Pressure?

Is that pounds per hour per horsepower? If so, those are awesome numbers. We will not run LOP.

232 HP for an IO-550N. Fuel flow at 75% best econ is 88-90 lbs per hour. TQ isn't specified but calculated should be about 488 lb-ft

The IO-550G is better but is only 210 HP.

Impressive numbers, nearing diesel fuel burns. My numbers in the first post are at full rich (I think). I doubt that any leaning was done during the dyno runs.

Diesel Engine BSFC?
 

Aren't Diesels more in the range of .26-.32?

Doug
RV-9A FWF / Mazda 13B

Yes, except for automotive.

What ECU are you using? Most modern automotive engines run pretty lean at mid-power. WOT, I'm not sure. Ross could chime in here.

550G/N specs
 

Using the std TQ/HP formulas, the 550N has 603lbs/ft of torque at 2700/30” where the Lyc 540 has 505lbs/ft at the same power setting. That is a substantial differrence.

I am pretty sure that the TCM 360 has 210HP - but at 2800RPM? Not sure.

The TCM 550G (280HP/2550RPM) can be converted to the N specs (310HP/2700RPM) by turning the little screw on the prop governor...

HP/Torque calculator: https://spicerparts.com/calculators/...que-calculator

Diesel is up to 20% to 30% more efficient and the fuel has 10% to 15% more energy density, and makes more low end torque than a petrol engine.

I drive a VW TDI Sportwagen and can get over 50 mpg highway, and it is a hoot to drive with low end torque starting from idle is 100% torque at 1750 RPM and stays flat as a board (in part due to torque limiter in computer, these cars can be uncorked).... Low speed around the corner acceleration is fun. Why not diesel in airplanes. Of course they have some. The issue is weight. Diesel engines are beefy to handle the pressures. Also certification cost.

The answer is Lycoming is supiror to any alternative engine... proven over and over.

The HP, FF, BSFC, charts are in the Lycoming manuals. This is for a Continental, BSFC looks like 0.38 is lowest.