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Old 02-10-2009, 12:41 PM   #4 (permalink)
Master EcoModder
Join Date: Apr 2008
Location: Michigan
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Bio Deezler (sold) - '03 Volkswagen Jetta GLS TDI
90 day: 50.78 mpg (US)

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You would have to be hardcore about economy to do this.

The gains could be noticeable, but at the expense of increased oil consumption and blowby. Does the crankcase ventilation go directly back into the intake on this engine? If not, the blowby, consisting of unburnt hydrocarbons, etc, could cause more damage to the environment than you would save in fuel consumption reduction. If you reduce the engine compression sealing ability far enough, you'll end up with lower power and worse economy.

As for the overall engine output at this condition, with only 1.5kW of total friction loss, it wasn't making much... Total engine friction power loss at low loads and speeds is often half the engine output. Your link is dead though so I'm not sure I have the whole story.
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