21 Mpg. How ?
Senior User
Joined: May 2003
Posts: 355
Likes: 0
From: Baton Rouge, LA
Originally Posted by smokestone52
The only correct way to compute milage is to do it mathmaticaly.
1. Fuel up to full
2. drive
3. enter miles driven
4. Fuel up to full
5. divide fuel into miles driven.
Hence, miles per gallon. This is third grade math!
1. Fuel up to full
2. drive
3. enter miles driven
4. Fuel up to full
5. divide fuel into miles driven.
Hence, miles per gallon. This is third grade math!
MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (3600 * MAF / 100)
= 710.7 * VSS / MAF
MPG - miles per gallon
14.7 grams of air to 1 gram of gasoline - ideal air/fuel ratio
6.17 pounds per gallon - density of gasoline
454 grams per pound - conversion
VSS - vehicle speed in kilometers per hour
0.621371 miles per hour/kilometers per hour - conversion
3600 seconds per hour - conversion
MAF - mass air flow rate in 100 grams per second
100 - to correct MAF to give grams per second
This may not be third grade math.
Senior User
Joined: Feb 2004
Posts: 389
Likes: 0
From: NorCal
Originally Posted by efx4
I have the Diablo Sport Predator on 91 tune, modified stock intake and dynamax race bullit muffler w/ side exit 3" exhaust. Mods haven't really changed fuel economy, but mileage improved after the truck passed around 10,000 miles. Truck has 28,000 miles on it now.
Senior User
Joined: Jul 2006
Posts: 488
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I got close to that ONCE....pure highway miles across North Dakota on the way to Montana...with the cruise around 75-80. Usually driving I get like everyone else. Speed plays the biggest part IMHO. 5.4 3.55 stock 17's. My Escort used to get 35-40....tough to haul my camper or dead deer in that...LOL
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Junior User
Joined: Oct 2007
Posts: 61
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I've got the P rated tires so 35 psi is it But I'm going to try to keep the tach under 2k when accelerating & see if this is going to get me close to 21 mark I'll let you guys know how this change in my driving does. Normally when I get on the hwy I accelerate above the 2k mark on the tach hope this helps it be great to get better gas millage with a v8 versos my old explorer. it would be icing on the cake. I finally had to retire it with 252k.
Senior User
Joined: Nov 2007
Posts: 131
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From: Mount Vernon, Ohio
Originally Posted by baitmaster
if you drive 55 in this town, by the time you get to work, you will have 3 imports smashed up in your truck bed. When you get in the fast lane, you better be able to pucker up and hit the gas.
Feel free to accelerate or go as fast as you want, or jack up your truck and put fat tires on it. It's your truck. Just don't whine about poor fuel economy.
Dale
MMNC (SS)(Ret)
Joined: Mar 2004
Posts: 11,604
Likes: 148
From: SE Georgia
Originally Posted by Aberdale Farm
Feel free to accelerate or go as fast as you want, or jack up your truck and put fat tires on it. It's your truck. Just don't whine about poor fuel economy.
Dale
Dale
but for those calling B.S. on 21 mpg...you get the MPG that reflects how you drive. I typically get 13 mpg in the city...but I also love the throttle. I can and have gotten 21 mpg on the highway.
55-60 does appear to be the sweet spot though.
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Joined: Apr 2004
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I'm still waiting for that magical 15 mpg. City driving I usually get 11-12. Highway...well, 95% of the time I have my toy hauler behind me so 7-8 mpg is normal. It's not that the trailer is heavy, it just pulls like a parachute, and I'm usually in a hurry running 80mph, which doesnt help.
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Joined: Apr 2005
Posts: 175
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i have found the trip computer to be very accurate, but 21mpg out of a 5.4? NO WAY unless you are running 50mph on level ground with no a/c or are outside pushing it downhill!! i have found the the best i have had was about 18.5 with 17.5 being the norm. i dont drive hard either and 70-80 will really drive it down.
jim
jim
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Junior User
Joined: Oct 2007
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Well I was able to finaly able to fill my tank so I should have my results by next friday found out when you try to keep it under or at 2k rpm when accerating to hwy speeds it seemed to take a while to shift into overdrive learnd to work it alitte differnt seems to help so I'm not hagging in 3rd gear so long I'll let you guys know how it goes.
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Joined: Dec 2007
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08 screw fx4 5.4 3:55's with factory 20's Just made a 554 mile round trip Dallas to Houston & got 13.99 miles per gallon. I made good time 3 hrs 40 minutes on the way down. 4 hours on the way back. It was very windy on the way back.
Senior User
Joined: Dec 2007
Posts: 162
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Originally Posted by bassaway
Yes, and that is why I said the onboard computer APPROXIMATES your gas mileage. The computer also calculates the mpg mathematically. However, this value is approximate because assumptions are made that the fuel/air ratio is ideal and the air flow through the intake is constant and laminar. Also, this method does not account for possible % errors in the MAF reading.
MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (3600 * MAF / 100)
= 710.7 * VSS / MAF
MPG - miles per gallon
14.7 grams of air to 1 gram of gasoline - ideal air/fuel ratio
6.17 pounds per gallon - density of gasoline
454 grams per pound - conversion
VSS - vehicle speed in kilometers per hour
0.621371 miles per hour/kilometers per hour - conversion
3600 seconds per hour - conversion
MAF - mass air flow rate in 100 grams per second
100 - to correct MAF to give grams per second
This may not be third grade math.
MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (3600 * MAF / 100)
= 710.7 * VSS / MAF
MPG - miles per gallon
14.7 grams of air to 1 gram of gasoline - ideal air/fuel ratio
6.17 pounds per gallon - density of gasoline
454 grams per pound - conversion
VSS - vehicle speed in kilometers per hour
0.621371 miles per hour/kilometers per hour - conversion
3600 seconds per hour - conversion
MAF - mass air flow rate in 100 grams per second
100 - to correct MAF to give grams per second
This may not be third grade math.
also the data you refrence above isn't what the 05 & up odb III uses for mpg caculation ; i guess that is what your trying to convey. It really uses some basic math. The variables are : axel ratio & tire revs per mile, transmission gear ratios - all very basic.
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