In town fuel mileage

My 57K mile 02 DC Pre Runner auto , 2.7 4cyl supercharged w/4.5lbs boost , Doug Thorley Tri Y shorty header , K&N CAI . Also running oem 4.56 gears and 265/75 -16 Toyo Open country mud tires . Stock tire size was 225/75-16

I'm currently seeing mid /high 13mpg city and if I use the freeway maybe 60 miles I might see mid 16mpg

Is this okay fuel mileage for my supercharged 4cyl Tacoma ?? . I'm contemplating having a Off Road shop in my area install 4.88's to bring the gearing back to stock with those 265's . regearing should give me back the 400plus rpm's I'm down right now

 

That's a big expense for a 400 RPM rise. While it won't do much to the MPG, it won't make it better either. Ditching the mud tires (for street use) would likely have more effect.

In your current MPG calculations are you using corrected miles to compensate for your ODO error from your tire/gear changes?

 

Just going from miles shown on my trip odometer . how do I compensate for odometer error ??

Prior to the Toyo Open Country mud terrains I had 265 /75 -16 Hankook Dyno Pro all terrains

 

You have to determine how much error there is, then factor that % into the calculation. You currently should be driving more miles that are displayed, meaning your MPG is actually better.

 

Multiply the miles by 1.08

 

How do I figure out odometer error ??

 

GPS

 

Thanks !!

I just recalculated my mileage and I'm 14.65 mpg

 

Did you consider his current 4.56 gears too? Or just the tires?

 

He said the 4.56s were oem so i assumed that was what came on his truck. Thats just taking in account that those tires are about 8% larger.

 

Missed the OEM.

A number like that doesn't even register with me as being a stock option. That's 1969 drag racing stuff. All in a legal environment of course.

 

Door Vin decal shows I've got 4.56 gears

 

You sure it didn't come with the 31s stock? Now that i think about im pretty sure you could only get those gears on 4 bangers with the factory 31s.

 

I'm all stock running same size tires you are with a lift and semi heavy rims, I get 22 mph around town and 24mpg on highway, I was actually just talking about supercharging the little guy today, but that big of a hit in mpg makes me think I should just go with a stock 3.4l or a supercharged 3.4l and just not have to think about how to pass people anymore

 

To the original mpg question i do think you should be seeing better than that. During normal driving out of boost the sc shouldnt really affect it that much. Heck on the 3.4 alot of guys see better mpgs.

 

Makes me want a v6 SC even more

 

Okay I double checked my vin plate decal on the drivers door sill


B04A /A340E .... translates to a 8" ring gear ,4 pinion open diff w/ 4.56 gears . the transmission is a A340E automatic

Factory tire size for my truck again looking at the decal is ......225/75 -15 and looking at the dealer window sticker that I still have shows that my truck was dealer optioned with the 265/75-16's

 

I know my truck left the factory with the speedo gears set for 265/70/16 tire and I am currently running the same size as you 265/75/16.

heres a pic to illistrate:

from what I know most trucks had this sticker... but many do not and never did despite the true intended tire size. I gained roughly 6 percent in travel-per-revolution with my 265/75/16's but they run true to the speedo and within 1mph out to 70mph.
so deff check the error range with a GPS before doing anything else to the truck.

 

No Armor, 31s, 3.4L S/C, seeing 20.8 average if all highway, and 18.6 city.