[revetec]

Originally Posted by hightower99

With only that single point it could be almost anything. Maybe at 2000RPM and 450kPa BMEP several variables come together to achieve the great BSFC. You can't tell me that it could have only been the bottom end design.

No one quotes their worst BSFC, only their best.

From comments made by the test engineer. I also took a blank head in to show them the design. He then brought in a head to show me how it should be done.

Originally Posted by hightower99

That is a highly simplistic list of variables. What about any synergy that exists in the system? What about all the variables like bore:stroke ratio, cam characteristics, oiling system, maybe the clearances in all the bearings in the engine approach absolutely perfect?

Are you saying that all engine manufacturers have got it so wrong in the areas you have identified?

Originally Posted by hightower99

BMEP =/= Avg. cyl. pressure. BMEP is normally calculated from torque being a function of torque and displacement. Therefore if you have a lower BMEP value and the displacement is the same then output must also be lower(for any given RPM because the torque is lower). Maybe you are actually talking about average cylinder pressure and not BMEP.

This is what I thought and conveyed this to Orbital. I was looking for a higher BMEP. They said that at any given output, the lower the figure the better.

Originally Posted by hightower99

I haven't been able to find much but there isn't much out there anyways. What I need to counter you is a single point where an engine produces similar (Gasp! maybe even better) BSFC ratings and I can't find that on the www.

I certainly don't spend the majority of time at 2000RPM, besides isn't this an aviation engine? My point was you should make a full BSFC map for the whole rev range and most loads. This allows everyone to see that the engine is always going to be more efficient and that it isn't just a lucky setup.

A lucky set up? hehehehe. You don't think after 100 years of conventional engine development that if it was a lucky set up that it would have been done before?

It is an aviation engine, but this doesn't mean that we are not pitching to auto manufacturers. We are. Automotive is our biggest potential market. Everyone we have talked to in this market state they are looking for lower BSFC figures. The full BSFC map will be done during final optimization of the top end. I'm sorry but this is a bit of a process to optimize and you'll have to wait until our next independent testing procedure occurs.

So you don't drive on the freeway often?