Engine efficiency maps

[gbent]

I have seen many engine efficiency graphs for engines at full rated power, but I don't think I have ever seen a set of graphs showing engine efficiency vs. RPM for different constant engine loads. I would like to see information for both SI and CI engines.

This would help show the best RPM for different loads, and could help decide on final drive ratios for vehicles. For constant RPM usages, such as a stand-by power unit or a pump engine, would show the most efficient load range.

There is a company claiming tremendous improvements on Class 8 (80,000 lbs. GVW) diesel mileage by using a hydrostatic drive with variable displacement pumps and motors. The engine is reported to run at 1200 to 1400 RPM.
If something less than full rated power is needed, is the lower RPM that much more efficient? Given the usual inefficiency of fluid drive systems, engine efficiency maps would help evaluate the accuracy of their claims.

On older carburated engines, maximum efficiency was often claimed to be just before the power valve opened. Is there a similiar situation on a EFI engine?

Thanks

 

[GregLocock]

Here ya go

http://www.geocities.com/SunsetStrip/4060/consumo.html

or

http://www.geocities.com/SunsetStrip/4060/Image33.gif

yes, they are used to design the gearing on vehicles.



Cheers

Greg Locock

 

[gbent]

Thanks, Greg. The graphs are interesting. It would be nice to know more about the engines, such as was the SI EFI or carburated, open or closed loop? Was the CI turbocharged?

Does anyone have access to American engine data? An EFI small block chevy and a pick-up type diesel would make an interesting comparison.

 

[1Bluegrass]

I think the best load maps are those that are done by auto makers who use Speed Density engine control systems.
They have to run the engine under every possible load situation the user might encounter; build the programming, sensor input and output controlling hardware to work over the whole range from cold start to the hottest ambients, meet trouble handling/reporting situations and federal emmission standards.