Interesting MPG comparison

[erin]

Thats why I was wondering, as mine with 255'sand 4.88's reads 80, but gps saya 71.6. So my mileage clocks more then actual, showing more miles covered per tank of fuel.

 

[tacollie]

I passed my girl friend doing 75 according to my speedo and she said she was going just over 80. Big O said that it would be off about 8%, but their calculated the 255's at 33.01 and they are a little taller. I have been told the taco speedos are a littlefast and so you arn't going as fast as you think. The thing is I accelerate a little slower and that is where my improvement probably comes from.

 

[Martinjmpr]

I passed my girl friend doing 75 according to my speedo and she said she was going just over 80. Big O said that it would be off about 8%, but their calculated the 255's at 33.01 and they are a little taller. I have been told the taco speedos are a littlefast and so you arn't going as fast as you think. The thing is I accelerate a little slower and that is where my improvement probably comes from.

Best way to check your speed is with a GPS unit.

 

[Super Doody]

I didnt bother with speedo re-calcs since I was just shooting to get a comparison between the two scenarios. I have the 3.4l engine-

Since the circ. of the the tires (30.7" stock vs. 31.8" current) varies by 3.5% wouldnt I have to actually add 3.5% on to my numbers to net actual mpg?

Roger on checking your spd withthe GPS . Your speed and Odo gauge has a certain percentage of error from the factory. Most people have found that with 265/75/16, their ODO is right no so no correction factor is need.

 

[tacollie]

I don't have a GPS unit so that is just my rough estimate.

 

[Grim Reaper]

I had an 85 with the 22r, reg cab with a shell, and I don't remember having to keep it hammered down most of the time.

How fast are you driving anyway? Back in 85 the speed limit was still 55 and I rarely went above 60.

My 86 4Runner don't like 2000 RPM. It can't maintain the speed if you hit a hill. I run 70 (to keep from getting run over) and it seems happy with that and 3K. Gets about 22mpg spinning 33x12.5 as checked via GPS.

With my 33's and gears (4.88) I should be turning 2750 rpm at 65mph.

To go 2250 RPM in 5th you would hit a whopping 53mph.

Grim Jeeper has a really nice side by side calculator that has most of the common transmission combos with the correct OD numbers.
http://www.grimmjeeper.com/gears.html