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Old 08-27-2008, 08:27 AM   #9 (permalink)
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Join Date: Jun 2008
Location: Toulouse, France
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scenic - '01 renault scenic
90 day: 43.09 mpg (US)

megane - '97 renault megane classic
90 day: 72.53 mpg (US)

dennisius - '06 Toyota Prius
Team Toyota
90 day: 69.27 mpg (US)
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Originally Posted by instarx View Post
Your instincts are right that bringing in hot air may have hurt your mileage. Diesels are very sensitive to intake air temperature. Hot intake air in a diesel is pure power loss since the limiting factor in diesel engine power is how much O2 there is in the cylinder for combustion. The more O2 the more power at a given fuel rate, and hot air simply has fewer O2 molecules than cold air.

Here is a copy of a post I made on a diesel forum I belong to:
Very interesting.

I have only diesels and I have just blocked the lower grill of my car. From the dash board the temperature is greater, but lower than when I'm at highway speeds.

I don't have any instrumentation so I'll take your informations into account when I have the results for my current tank.

Save money & CO2 at home :
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Earth and health are priceless, so are kilotank and AT-PZEV
Best Mégane tank: 1268.9mi @ 77.847 MPG(US)
2008/06-2011/10 saving:
  • 5725.5 kg CO2 (5342.6+382.9)
  • Diesel / Money: 42.17% = 2446.25€ = 3357.26$

megane : thread - kill switch.
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