The tricks up my sleeve... Methods I may implement for better FE.

[omgwtfbyobbq]

Originally Posted by trebuchet03

Careful... that is quite easily a fallacy (slippery slope?)...

Thermal efficiency and fuel economy are very different things If you want to compare the efficiency of heat engines, compare the energy cost per kW

If the same test compares the same cars, over the same cycle, with the same engine, and (taller) gearing that's favorable in the turbocharged car for fuel efficiency, with the turbo car getting worse mileage than it's NA counterpart with shorter gearing. It's evident that the turbocharged engine is less efficient (over that cycle ) than the NA engine imo. I dunno what else to control for...

Originally Posted by landspeed

I would say two other reasons are, that turbo engines (at least mine) might enrich the fuel mixture at a lesser throttle than a NA engine, presumably because if you go on full boost, the engine heats up inside, and then cruise at part throttle, it might detonate due to the extra heat that you wouldn't get in a NA engine.

Also, turbo versions of engines generally have a lower compression ratio, again making the engine less efficient. Diesels have an extremely high compression ratio.

Yes. I don't think that's a problem at part load, since at most part load the turbo'ed engine probably still makes less power than the peak for the NA version. More throttle enrichment on WOT and peak might be present, but even then, the turbo Eclipses were intercooled to avoid that very problem. I think all things being equal, at part load, Mitsubishi still had to have the car at stoich.

Originally Posted by Snax

landspeed has it correct. It's about safety margins. While a higher compression motor can afford the random detonation here and there, a turbocharged motor is far less tolerant to it as cylinder pressure is increased. One good detonation event can literally blast the piston ring lands apart or worse. That simply doesn't happen with your average NA motor. So in the case of the turbo, they map extra fuel in to mitigate that possibility as well as reduce timing advance.

I would guess that tolerance to detonation has more to do with the power/L and engine speed where detonation occurs, than any inherent difference between a turbocharged and NA engine. In any turbocharged engine, they need to have more fuel, because they have more air, compared to aNA at the same speed. But, the engine is likely still at stoich for most driving conditions, due to emissions regulations. Any risk of detonation will likely be mitigated a bit by way of well designed intercooler. The turbocharged Eclipse motor put out ~100hp/L, which is what some NA motors can do, so it shouldn't be a matter of adding additional fuel and running the AFR richer than other manufacturers in a well designed system imo. I think you touched the point, different CRs, which imo is why the turbocharged motor was less efficient over the EPA highway cycle. There is probably some portion of the load map where the turbocharged engine is slightly more efficient due to higher peak cylinder pressure and turbocharger efficiency, but because of the supposed power requirements of today's vehicles, most drivers, and the EPA highway test, seldom see that portion. So, for most low load operation, the turbocharged engine will be less efficient than the NA engine imo, and this seems to be backed up by the EPA highway results with the same car/engine.

P.s. You sure that bike is 700 MPG Equivalent Energy?

Originally Posted by SVOboy

I am just saying that I think the diesels honda and toyota bring to the us in the next few years will beat VW in the emissions department, Im not saying that some of their cars aren't comparable.

EDIT: For example, the diesel released in the US will be a 50 state diesel, which no one else has right now: http://www.iht.com/articles/2006/05/...rg/sxhonda.php

Orly? Yarly! Honda, Toyota, or VW may have the cleanest 50 state diesel, but Honda's offering in Europe hasn't been very different, so I doubt it will be much different if/when released over here.