Is my MPG too good?
08-05-2014, 01:06 PM
#1
3rd Gear Member
Thread Starter
Join Date: Sep 2011
Location: Florida
Posts: 632
Is my MPG too good?
Hey guys, I keep hearing from my buddies (who do not have a foxbody) that I should not be getting as good as gas mileage that I am for what my build is. They keep telling me that something is not right, but I think they are crazy. If I drive it normal I will typically get 18-19 MPG (this is mostly highway and some city), but if I baby the hell out of it I will get 20 MPG.
The only mods I have done are BBK CAI, C&L 73mm MAF, 70MM TB, Trick Flow intake, and a full exhaust (long tubes, H pipe, and flowmasters cat back). I have a T5 trans with a good clutch, 3.08 gears in the rear, Nitto 555's (255/40R17's) tires, and a very decent suspension. Granted my motor is CLEAN, tuned, and running strong, but is this too high? I recently installed a wideband in it, and it does not seem I am running lean. If I drive it normally, I will stay at exactly 14.5-15.2 During WOT it will go down to 12.2, to 17 when I take my foot off the gas, and stabilize at 14.7 during idle. What do you guys think? What is your HP to MPG ratio?
The only mods I have done are BBK CAI, C&L 73mm MAF, 70MM TB, Trick Flow intake, and a full exhaust (long tubes, H pipe, and flowmasters cat back). I have a T5 trans with a good clutch, 3.08 gears in the rear, Nitto 555's (255/40R17's) tires, and a very decent suspension. Granted my motor is CLEAN, tuned, and running strong, but is this too high? I recently installed a wideband in it, and it does not seem I am running lean. If I drive it normally, I will stay at exactly 14.5-15.2 During WOT it will go down to 12.2, to 17 when I take my foot off the gas, and stabilize at 14.7 during idle. What do you guys think? What is your HP to MPG ratio?
Last edited by yurizx6r; 08-05-2014 at 02:05 PM.
08-05-2014, 01:45 PM
#2
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
What's your rear gear? That would have a huge impact on Highway Mpg. a shorter rear gear like 4.10 and 3.73 will do far worse than a taller rear gear like 3.27 or even 2.73.
Other than that, they're just jealous
Other than that, they're just jealous
08-05-2014, 02:10 PM
#4
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
sorry, I missed the 3.08 in your original post. I would say a good chunk of your good MPG on highway is due to that. Swap them with 3.73 or 4.10 like your friends probably do and say bye-bye to that MPG.
Other than that, a good setup on your timing, clean fuel and air intake would all help. I'm guess you tend to do a good job in maintaining your ride based on your "CLEAN motor" statement
Other than that, a good setup on your timing, clean fuel and air intake would all help. I'm guess you tend to do a good job in maintaining your ride based on your "CLEAN motor" statement
08-05-2014, 02:26 PM
#5
3rd Gear Member
Thread Starter
Join Date: Sep 2011
Location: Florida
Posts: 632
lol Yeah I am a maintenance freak. I've taken this motor apart and cleaned everything from heads to toes. Injectors are spotless, Mobil 1 every 2,500, Red Line gear oil, sea foam cleans every 8,000, etc etc. I take care of my rides the best I can. But when my buddy (who basically taught me everything I know) keeps saying "your going to burn a piston ring from running so lean, you shouldn't be getting that type of gas mileage." Over and over, despite what the wideband is telling me, I can't help but wondering........... damn is he right?
08-05-2014, 02:28 PM
#6
3rd Gear Member
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Join Date: Sep 2011
Location: Florida
Posts: 632
Obviously if I have fun with the car I will get like 15-17 max if I'm shifting at 3,000 plus, so that does not worry me, but where I live there is so much damn traffic and dumb people on the road, it's very hard to get on it and have fun.
08-05-2014, 05:49 PM
#7
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
If you were running lean your plugs would show it too (white or heavy, light grey soot), and you would be overheating or running very hot all the time. If that's not present. Tell your friend to stop being jealous 
08-05-2014, 06:04 PM
#8
2nd Gear Member
Join Date: Sep 2011
Location: Ohio
Posts: 325
I usually got 20 mpg around town, and 24 on the highway, with a 3.73 rear, with a hci (TF heads) 306. I would accelerate however I felt like, but then cruise between 1500 and 2000, with a lot of my cruising in 5th. Your mileage is on par.
08-05-2014, 06:14 PM
#9
3rd Gear Member
Thread Starter
Join Date: Sep 2011
Location: Florida
Posts: 632
Nice reldla! My (stock) temp gauge pretty much stays between the top of the "A" and the middle of the "M" (whatever that means). That's not running hot on that car right? I guess keep in mind I have a new ford racing water pump, fluidyne radiator, an OEM 195 degree thermostat, and a 50/50 mix of coolant. Is that where I should be? I live in Florida and the summer here sucks.
