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Old 11-16-2010, 08:51 PM   #29 (permalink)
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Location: Arkansas
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The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
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The only way I could see forced induction helping is if it is coupled with downsizing the engine displacement, and/ or giving the transmission a very long legged overdrive. A mild boost designed to kick in at low rpms would allow lugging in lower gears and being able to stay in overdrive in more situations.

IIRC the new Corvettes are supercharged, but with a 1:0.50 overdrive gear ratio (it may be even higher, can't find the info) it could achieve ridiculously high fuel economy for a v-8 performance car. A friend told me his buddy could reliably get 30 mpg from his Corvette 6 speed when cruising.

One example is this quote from Ford:

EcoBoost uses gasoline turbocharged direct-injection technology for up to 20 percent better fuel economy, 15 percent fewer CO2 emissions and superior driving performance versus larger displacement engines
I'd been reading about OEMs using turbos to increase economy while minimizing performance losses, and this is one example.

Another quote worthy of consideration is this one from the above article.

“Compared with the current cost of diesel and hybrid technologies, customers in North America can expect to recoup their initial investment in a 4-cylinder EcoBoost engine through fuel savings in approximately 30 months. A diesel in North America will take an average of seven and one-half years, while the cost of a hybrid will take nearly 12 years to recoup – given equivalent miles driven per year and fuel costs,” he said
RIP Maxima 1997-2012

Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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