Levi Pearson wrote: > Well, diesel and gasoline engines are somewhat different beasts.
It was you that made the blanket statement about turbos, not me. I used diesel engines to prove that your statement about a turbo *always* cannot possibly increasing efficiency because it consumes more power (which is true) to be false. > If you're driving faster than before, it's probably true that you were > able to accelerate to that speed much faster, and perhaps wasted less > fuel getting to that speed. I can guarantee, though, that you're > using more fuel at 90mph than 70mph simply because air resistance > increases dramatically. Power required to overcome aerodynamic drag > increases at the cube of velocity. Of course. As I said, cruising at 90 MPH uses more fuel than cruising at 70 MPH. That's obvious. Additionally, you are correct about the effect of drag. But MPG-wise, his car would get better mileage at 90 than it would at 70. Hence the efficiency was best at 90 MPH, despite the higher fuel consumption rate. The car was more efficient when powering the turbo at 90 MPH than at the lower speeds where the turbo is not boosting (and hence not consuming as much energy). Now the real test would be to compare the turbo car with the naturally-aspirated one. > I'm not sure how you measured this efficiency gain on Alex's car, or > even what kind of car it is. Gasoline or diesel-powered? What > components changed when the turbo was installed? I'm not doubting > that he's getting better mileage overall now, as I've seen that happen > before after turbo installs on gasoline-powered cars, but that's not > necessarily due to the turbo itself, but on other factors that changed > due to the turbo install. The efficiency is being measured simply in MPG, which is the only metric that counts when it comes to the efficiency of cars on the highway. Alex can pipe in with the specifics. But it was definitely a gasoline engine, on a V-6 I think. Highly anecdotal, granted. It's his story, so I guess I'll not say anything more on it. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */