Turbo Boost and FE

[GasSavers_Hal9000]

Originally Posted by Gollum

Oh, and just because a turbo increases thermal efficiency doesn't mean better FE. Thermal Efficiency is about how much power an engine is making for the given heat generated by the engine. This has nothing to do with fuel usage under a cruise or around town condition.

I've got disagree with you here. If engine heat can be equated to wasted fuel energy (which it can), then increased thermal efficiency will mean that you're extracting more energy per lb of fuel burned and converting it to mechanical energy. Wether you use that to accelerate faster, or cruise a greater distance at low throttle openings is primarily up to the driver. Engine design can also affect this but for a given combination, you have a lot of choices (The force is within you.... you must use it wisely... )

What IS true is that a turbo may only increase the thermal efficiency of the engine at certain rpm/throttle openings. The goal is to get the increases in the area where they will be most useful for FE fans. That's a different goal than HP fans.

On another (although similar) note, I've had an idea rattling around in my head for years now.... It's for a true tunnel ram intake that might produce a small amount of positive pressure at highway speeds. It would have to incorporate a turbo style BOV to avoid pressure waves, and would need a long straight stretch to work (my original idea was for a rear-engined VW), but it would probably have the same effect on the highway as a Low pressure turbo would.... If there are any VW owners around who want to do some fabrication, I'll be happy to share my thoughts.