Re: How much does rear gear ratio effect HWY gas mileage?
[Re: 360view]
#2509694
06/17/18 06:57 PM
06/17/18 06:57 PM
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Joined: Jan 2003
Posts: 3,575 The Netherlands
BigBlockMopar
master
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master
Joined: Jan 2003
Posts: 3,575
The Netherlands
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... Notice that in nearly all BSFC graphs the best spot is at low vacuum but at an engine speed where the pistons are moving less than 1500 feet per minute. ... Thinking EFI on an earlier built car, which ofcourse is lacking EGR; What would one think of, instead of normally optimizing ignition timing at cruise rpm, now retarding ignition timing instead. Letting the engine get a bit less eficient so more throttle is needed to maintain speed. More throttle, less vacuum (with same speed). Would this have a similar effect as an EGR?
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2509849
06/18/18 07:19 AM
06/18/18 07:19 AM
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Joined: Aug 2003
Posts: 2,468 Answering the call of the wild
ThermoQuad
top fuel
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top fuel
Joined: Aug 2003
Posts: 2,468
Answering the call of the wild
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That's a lot of turd polishing there....no that's a lack of knowledge on your part...and showing it on the internet
The fsm is a poor substitute for proper bearing preload. Trying to figure out how to make a 1970 automobile go 140 mph without vibration and stopping issues will lead one to figure out how to set up front bearing preload with the proper tool. It does indeed effect gas mileage and proper braking.
Rolling resistance and engine efficiency is the issue here and it does not matter what kind of car it is.
Last edited by Dilbert; 06/18/18 07:20 AM.
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2509940
06/18/18 12:32 PM
06/18/18 12:32 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Most authors of articles in the media have a degree in "useless studies" and know virtually nothing about what they write about. What qualifies them as "knowledgeable" is that they know slightly more than the other "journalists" they consort with.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: 360view]
#2510068
06/18/18 05:36 PM
06/18/18 05:36 PM
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Joined: Nov 2010
Posts: 3,696 jersey
Spaceman Spiff
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master
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Posts: 3,696
jersey
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Monday Wall Street Journal has a front page article on getting better MPG from pickup trucks. Author of article seems to believe that simply putting a very small cubic inch engine in a pickup is the majority of the effort. Almost no discussion of gearing and transmissions. I’d bet a 440 would get better mileage in a fully loaded c-body, than a slant 6 would, all other options being the same.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2510176
06/18/18 10:02 PM
06/18/18 10:02 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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Axle efficiencies come into play. The internals of the transmission [working through a fluid] driveshaft and axle gears [working through a fluid] have to spin at higher rates, consuming more energy.
Lower [numerically] gear sets offer increased efficiencies, this can be seen in the trucking industry by just researching "downspeeding". If you have the torque on-tap, slowing everything down offers a benefit in fuel economy.
By improvement, I am referring to single digit percentages, which may or may not be significant to you. In trucking, it's a big deal. If I turn a 13 or 15 liter engine 200 times less per minute while producing adequate torque, it doesn't take long to realize there is some energy conservation taking place.
For what it's worth, I do work for a Class 8 truck OEM and have spent some time on the subject.
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: cudaman1969]
#2510200
06/18/18 10:59 PM
06/18/18 10:59 PM
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Joined: Nov 2010
Posts: 3,696 jersey
Spaceman Spiff
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master
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jersey
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Big engine or little engine, still takes the same hp to go a certain mph, all things equal on the vehicle. but when the smaller engine makes 1/2 the power the larger engine does, it's going to be working harder at that same hp level.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: Spaceman Spiff]
#2510227
06/18/18 11:52 PM
06/18/18 11:52 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
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Posts: 12,419
Kalispell Mt.
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Big engine or little engine, still takes the same hp to go a certain mph, all things equal on the vehicle. but when the smaller engine makes 1/2 the power the larger engine does, it's going to be working harder at that same hp level. No, they will be doing the same work, actually the bigger one would as it has to overcome friction from bigger parts or longer strokes or both.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2510228
06/18/18 11:56 PM
06/18/18 11:56 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
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Kalispell Mt.
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Also the smaller engine has less distance within the chamber for the flame front to travel across. And since the smaller engine will be operating at a lower vacuume leval the air and fuel molecules will be closer together upon ignition and therefore will burn more completly. Goody could probably back this one up as that is the reason why they run engines with just barely enough power to pull the maximum load the maximum desired speed and then gear it to get the load moving.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2510291
06/19/18 08:23 AM
06/19/18 08:23 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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I learned a lot about engine performance under different pavement, grade, wind and speeds using this relatively inexpensive add-on trip computer: http://www.autospeed.com/cms/article.html?&title=The-OzTrip-Car-Computer&A=0639At the time I bought mine 62 USA pennies equalled a Austrailan Dollar. After having the Oztrip for awhile I realized I could go beyond the instant MPG and use the trick of first reseting one of the three mileage memory counters, then watching the Gallons digital readout until it changed by exactly 1.00 gallons, or 2.00 gallons, etc As AndyF says above, seeing how fuel consumption changes as you drive is very educational. Climbing 4% grade hills at the same MPH in different transmission gears is eye opening.
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: HotRodDave]
#2510386
06/19/18 02:13 PM
06/19/18 02:13 PM
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Joined: Nov 2006
Posts: 2,256 IL
furious70
top fuel
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top fuel
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Posts: 2,256
IL
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Big engine or little engine, still takes the same hp to go a certain mph, all things equal on the vehicle. but when the smaller engine makes 1/2 the power the larger engine does, it's going to be working harder at that same hp level. No, they will be doing the same work, actually the bigger one would as it has to overcome friction from bigger parts or longer strokes or both. +1 If a bigger engine got better or the same mpg tooling around we'd all have bigger engines in our late model cars... Throttle open more = better air and less work to overcome pulling air through the tiny straw of cracked throttle blades.
70 Sport Fury 68 Charger 69 Coronet 72 RR
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Re: How much does rear gear ratio effect HWY gas mileage?
[Re: ragtop]
#2510692
06/20/18 09:32 AM
06/20/18 09:32 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
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Posts: 8,162
USA
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Anyone here on Moparts presently driving a Ford F150 with the 2.7 L twin turbo V6 ? Does the Ford trip computer allow you to view the MPG at a steady level highway speed? How many psi of boost is needed to drive in the 60 to 75 mph range on a level highway? http://www.wardsauto.com/engines/2018-winner-ford-f-150-27l-ecoboost-twin-turbo-v-6
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