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Most efficient IC recip engines

Most efficient IC recip engines

(OP)
And what are the BSFC numbers for them?
I can think of one gasoline engine in the 50's running in the range of .32 lbs / bhph.
And .26 for a diesel engine.

RE: Most efficient IC recip engines

one gasoline engine in the 50's running in the range of .32 lbs / bhph
You mean 0.42? The latest Prius has the highest thermal efficiency of any mass produced gasoline engine - around 40% TE (0.32 lb/hp.hr)

On a more serious note, the current Formula one engines have peak efficiency in excess of 50%. (0.28 lb/hp.hr)

je suis charlie

RE: Most efficient IC recip engines

grunt, does that F1 number include KERS?
The Wiki list is funny because it lists a combined cycle power plant, and includes the generation of the steam cycle.
The eff of some old aero engines is impressive.
The fact that ICE is most eff at WOT and max torque makes hybrid design interesting...

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Most efficient IC recip engines

Quote:

The fact that ICE is most eff at WOT and max torque makes hybrid design interesting...

Do these BSFC curves take into account the "Power Enrichment" that is needed at higher load (presumably max torque is max load by BMEP?), or do they presume an impractical stoich mixture at all operating points? I'm kind of surprised that reduction in pumping losses from the WOT manages to overcome the big fuel squirt needed to prevent detonation.

Pretty impressive numbers from those old aircraft engines, and the larger displacement stuff in general.

RE: Most efficient IC recip engines

"Power enrichment" isn't always needed. If the engine is mildly tuned, running at stoich at full torque (not necessarily max power output) won't hurt anything - not enough heat to melt a valve or a piston. The fact that your Toyota Prius engine makes (say) 78 horsepower calibrated at stoichiometric instead of (say) 80 if it were (say) 10% rich at full load, doesn't mean a thing to the type of people who buy that type of vehicle.

RE: Most efficient IC recip engines

grunt, does that F1 number include KERS?
The Wiki list is funny because it lists a combined cycle power plant, and includes the generation of the steam cycle.
The eff of some old aero engines is impressive.
The fact that ICE is most eff at WOT and max torque makes hybrid design interesting...


1. No. KERS energy starts at the ICE, is used to accelerate the car, is recovered during braking and stored, then used again - recycled. Nothing to do with efficiency of the iCE.
2. As it should. The steam cycle is still generation useful energy from the same fuel going in. Efficiency = (useful output)/(cost of producing that output)
3. Yes. The Wright Turbo Compound and the Napier Nomad (also a compound) in particular.
4. Not universally true. Because more output is available with richer (fuel wasting) mixtures, most SI ICE's are more efficient around 70-80% load. The rpm for peak efficiency is usually close to peak-torque-rpm but not always. Yes hybrid design is interesting. There are BSFC maps for Priuses gettin around the net which include a "peak efficiency line" ("Basic Operating Line")- a plot of best efficiency point at various power levels - which is clearly where you ideally want to be with a hybrid (or any other) transmission.

Link

je suis charlie

RE: Most efficient IC recip engines

(OP)
Qoute>>>>>>"one gasoline engine in the 50's running in the range of .32 lbs / bhph
You mean 0.42? The"<<<<<END QOUTE...
.32 is the number.

RE: Most efficient IC recip engines

You just pulled .32 out of your memory?

That's an incredibly low value for an engine from that era.

RE: Most efficient IC recip engines

Agreed, 0.32 lb/hp-hr is a very impressive number for a far-from-recent SI engine, however Napier achieved that benchmark in 1927 with the Lion engine that was prepared for the Schneider Trophy race of that year with a 10:1 CR [Ref. Setright's The Power to Fly, page 81], although I am not clear what racing fuel concoction was used. I seem the recall reading somewhere else that the 0.32 number from the Lion was validated in separate tests by Ricardo.

PJGD

RE: Most efficient IC recip engines

Well... if the fuel being used to produce a BSFC number isn't known, that number doesn't mean too much.

RE: Most efficient IC recip engines

(OP)
100/130 av gas
Correction
115/145

RE: Most efficient IC recip engines

I like the Electro-Motive rule, 1 gallon of lube per cylinder per day at rated load. The low particulate power assemblies have cut that nice ratio in half, though.

RE: Most efficient IC recip engines

Thanks to GregLocock for originally posting this explanation of the working of a diesel engine.
Link
Efficiency is well summed up in the following sentence:
" Of all the power generated, some goes to work, some goes to friction, some goes to heat, and the rest goes to hell, which is all that you could expect under the circumstances."

Bill
--------------------
"Why not the best?"
Jimmy Carter

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