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TXFlyGuy
01-30-2020, 12:24 PM
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.

Grum.man
01-30-2020, 12:34 PM
The IO-550 line gets around .37-.38 LOP at 75%

TXFlyGuy
01-30-2020, 12:50 PM
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.

Grum.man
01-30-2020, 12:56 PM
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.

TXFlyGuy
01-30-2020, 01:50 PM
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.

dlomheim
05-04-2020, 12:22 PM
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.

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

Doug
RV-9A FWF / Mazda 13B

BillL
05-04-2020, 08:31 PM
Yes, except for automotive.

scsmith
05-04-2020, 09:41 PM
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.

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.

F1Boss
05-05-2020, 06:30 AM
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.

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/horsepower-torque-calculator

gmcjetpilot
05-16-2020, 10:36 PM
Aren't Diesels more in the range of .26-.32?Doug RV-9A FWF / Mazda 13B 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.
https://s30121.pcdn.co/wp-content/uploads/1999/06/Basic-engine-curves.jpg

rv6ejguy
05-17-2020, 09:17 AM
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.
https://s30121.pcdn.co/wp-content/uploads/1999/06/Basic-engine-curves.jpg

If we are talking auto engines here, the latest SI engine designs from Toyota match the BSFC figures of auto light diesels. Toyotas Dynamic Force engines, introduced in 2018, have a thermal efficiency of 40-41%. https://www.sae.org/news/2018/04/toyota-unveils-more-new-gasoline-ices-with-40-thermal-efficiency

This is because the compression ratios are in the 13-14 to 1 range and the Otto Cycle is actually more efficient than the Diesel Cycle.

Diesels also don't produce more torque or more power than an equivalent SI engine of the same displacement at the same boost pressure. If you have an apples to apples example to support your statement, please cite it here.

Most OEM SI auto engines require a very rich mixture (around 11.0 AFR) at high power levels to keep piston crown temperatures down to survivable levels.

Despite the generally old tech in Lyconentals, they are surprisingly efficient at cruise. Running LOP in cruise, they can match the BSFC figures of 2 stroke aero diesels (think WAM) and come within a hair of 4 stroke aero diesels such as the Austro and Thielert. With the addition of high CR pistons, EFI, EI and tuned length intake and exhaust systems, they can match the diesels on cruise BSFC.

Dave Anders has done some great work in this area recently and you'll see some more info on his latest experiments shortly.