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Old 03-28-2008, 10:35 PM   #3 (permalink)
LostCause's Avatar
Join Date: Feb 2008
Location: California
Posts: 504

Thunderbird - '96 Ford Thunderbird
90 day: 27.75 mpg (US)
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Awesome video...I hope we get more driving technique videos put up on this site.

Vacuum gauges are a tricky subject for me. High vacuum indicates low throttle load which should mean low fuel consumption, but engine's operate at their lowest efficiency under low load...trying for high vacuum seems like rooting for the bad guy.

I think the gauge would be very helpful in determining the value of a WAI (warm air intake). A WAI will lower charge density, causing a decrease in power, forcing a wider throttle opening. If lower vacuum is seen for a given speed then you know the WAI is working as pumping losses are being reduced. Other mods like opening up the air box might be quantified also.

I'm not sure how load is calculated, but I believe it has something to do with torque. Essentially, it represents the force being placed on the engine. Engine's operate at a higher efficiency when producing high torque, so driving with load seeks to maximize the time the engine is in this band.

- LostCause
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