Better MPG with gear change - WHY ? [message #357965] |
Sun, 23 August 2020 09:14 |
hertfordnc
Messages: 1164 Registered: September 2009 Location: East NC
Karma: 0
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I've seen it said here many times that folks claimed better MPG after switching to a higher final drive ratio.
Also in my Ford Excursion groups, many people claim better MPG after going from 3.73 to 4.10
BUt i know a few car engineers and they are pretty smart guys so when something beats OEM design I am always suspicious.
In the case of the Excursion, it's often related to compensating for larger tires.
Are there other explanations?
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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Re: Better MPG with gear change - WHY ? [message #357992 is a reply to message #357965] |
Sun, 23 August 2020 19:40 |
JohnL455
Messages: 4447 Registered: October 2006 Location: Woodstock, IL
Karma: 12
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More vacuum with less load (higher numerical gears) means the primary rods stay pulled in more of the time, metering less fuel. That gives better MPG even with more combustion events per mile.
John Lebetski
Woodstock, IL
77 Eleganza II
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Re: Better MPG with gear change - WHY ? [message #358010 is a reply to message #357965] |
Mon, 24 August 2020 11:16 |
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Matt Colie
Messages: 8547 Registered: March 2007 Location: S.E. Michigan
Karma: 7
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I'm sorry.
I did write a page long explanation, but the forum dumped it when I tried to post it. I don't have time to redo now.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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