[hightower99]

Originally Posted by revetec

Don't get peak performance/output confused with peak efficiency, which you are. A higher BMEP produces more outright performance but the lower the BMEP for a given output provides a greater efficiency. One thing you are not factoring in is the manifold load of the engine at that BMEP figure point.

I believe you are misunderstanding what I said. Say you have a 2L engine and it produces 200HP (149kW) at 8000RPM, this means it is producing 131.3lbs-ft. of torque (178Nm) at 8000RPM. The calculated BMEP is then: 4*π*178Nm/0.002(m^3)= 1118.4kPa BMEP. Now the only ways to change that figure are: change dispacement or change the torque. As long as it is a 2L engine producing 131.3lbs-ft. (178Nm) of torque then the BMEP is always going to be 1118.4kPa. However the output (I am assuming you mean power?) can be pretty much anything depending on RPM. If you want a lower BMEP for any given output then you need to rev higher, which is not good for efficiency. If you are talking about avg. cyl. pressure vs. torque then that is mechanical efficiency.

Originally Posted by revetec

Try changing up a gear or buy a car that is more modern. Most cars I have driven is at around 2,000rpm at 100kph in 5th or 6th gear BTW: My car with a 5.7litre V8 and auto trans sits around 1,500rpm at cruise 100kph.

I loath how you try to simplify/generalize everything. I told you what the average RPM is for me and why. Accept it.

Originally Posted by revetec

This is because an engine is most efficient at around 3/4 load and from 3/4 to full throttle the performance gain is not great, but there is a higher fuel consumption. So the figure at full throttle is rarely used or quoted.

I think you misread what I posted again. I said the info I see on the net is usually WOT BSFC figures. Therefore to make a fair comparison I would have to use WOT figures for your engine.

Originally Posted by revetec

It's the same result as maintaining power and decreasing BSFC figures.

No it isn't and I thought I explained why... didn't I?

Originally Posted by revetec

Take your car for an example. If we were to change your final drive ratio to provide a 100kph cruise whereas you engine is operating at 2,000rpm, the result would be?

I can already cruise at 100km/h at about 1900-2000RPM but that is a moot point because I rarely cruise at 100km/h. I either cruise at about 80-85km/h or 115-120km/h and even then I cannot maintain a stable cruise for very long (because of how the road system is designed in Denmark). Personally I think my final drive is abit high.

Originally Posted by revetec

Another point I can add is that if we were to use our engine in a power generator type application. The engine will operate at one specific speed. A lower BSFC will provide less fuel consumption per kW-h which makes it more economical to produce electricity from this powerplant regardless of the efficiencies in other RPM ranges. A huge market for us.

Well think about that for a moment. You have to maintain the engine at 2000RPM and 450kPa load (the only point where you have proved high efficency) which means that the engine can only make about 86Nm of torque which at 2000RPM means you are only making about 18kW of power. Now knowing that the current market for 18kW generators is around the price range of 3700-4700USD and normally use air or watercooled 1L V-twin engines. Do you think you can price your 2.4L revetec generator competetively? Keep in mind that your engine is barely making 18kW at that point when normally 18kW generators need engines that produce 22-24kW