LB7: Poor mileage with bigger injectors?

[jonathancasey19]

I consistently hand calculate an average of 15.5 mpg running 45% over Exergy injectors with 35x12.50r20 tires and a Cognito 4-6" lift kit. During the winter, I lower the truck (approximate lift kit ~ 200 lbs), swap back to 285's and stock wheels. I average 18 mpg. Hard to believe a difference of 107.2 lbs of rotating mass between wheels/tire combos can improve almost 3 mpg.

I love my tuning. It says on the biggest tune 2450 pulse all the time. Just wish I could get better mileage here. I've got friends with LMM's from same tuner, running 100% injectors getting over 20 mpg. Hell my own tuner hand calculated 23 mpg with his LLY, 100% injectors and s475.

For those of you running bigger injectors in an LB7, what are you seeing?

 

[rickettzusaf]

Are you running his mileage tune? Or have you found that you can get better mileage not on it? Is this average in city or highway or combo? Do you have the 6 spd added to your 5 spd or the original 5spd?

I have found that I get better mileage with his built trans mileage tune vs the stock trans mileage tune. I average 17.6 driving 60 on the back road and 45 through town going 11 miles one way to work. Last time I did a highway trip I couldnt get over 19.6 and was averageing 16.6 avg at that time.

 

[DIESELMAFIAPER.LB7]

I run about 15ish as well unless its all freeway then i get around 19 also running 45% overs

 

[Dirtymaxx03]

i think the drastic difference in mileage between the different tires may have something to do with your odometer/speedometer not being calibrated for the appropriate tire size. When you run the 35's, do you calibrate the speedo in the tune?

 

[Chevy1925]

in town im at 16mpg right now but i have a hard time stayin off the throttle. on stock injectors id only average 15 so i cant complain. on highway i was averaging 19-20mpg on the first mileage tuning steve did for me. i havnt ran the newest tune on the highway with an empty truck yet but id expect a solid 20, maybe 21 mpg. on stock sticks thats right where i was before.

 

[Maricopaagent]

Man.. I get chit milage then..

50% in town stop n go, 50% highway 75 plus.. I get 14.5 avg..220 tune..

I do have a heavy foot though.

 

[jonathancasey19]

i think the drastic difference in mileage between the different tires may have something to do with your odometer/speedometer not being calibrated for the appropriate tire size. When you run the 35's, do you calibrate the speedo in the tune?

The speedometer is not calibrated for 35's. You would need to calculate the difference of revolutions per mile to determine how much further you are actually traveling per tank. Off the top of my head, just a guess, it would involve the difference in circumference of the two tire sizes, RPM's etc...sounds like a headache of conversions.

OR........

You simply base it on percentage. Not sure if this is correct. My 35's are actually 34.8" tall and smaller tires are 32.8". That's a percent difference of 5.75. Let's say I get 350 miles to one tank (23 gallons) . That's 15.2 mpg. Given the percent difference, I actually traveled 370.1 miles. That's 16.1 mpg. A difference of 1.1 mpg error haha. May not sound like a lot but it certainly adds up.

 

[DeMax LB7]

im checking my first tank this week with 100 overs.

 

[Kspen90]

The mileage difference is definitely because of the tires if you aren't recalibrating your speedometer when you change tires.

 

[fast03]

tire calculators all over the internet. IIRC about 13% for 35s depends on exact tire size. so the calc goes like this:
mileage driven x 1.13(tire size correction) = actual mileage / gallons used= mpg.

 

[Gmclbz]

im checking my first tank this week with 100 overs.

I got around 19.5 on the highway with my 100 overs...

 

[Fastorange]

do you have a 3 inch y bridge and piping yet? i just installed a rick lance 3 inch pipe and bridge on my lly and it made a diffrence...

 

[jonathancasey19]

do you have a 3 inch y bridge and piping yet? i just installed a rick lance 3 inch pipe and bridge on my lly and it made a diffrence...

No I don't. I was told the stock LB7 y-bridge is not as restrictive as other generations. Spending what $350ish worth it?

 

[jonathancasey19]

tire calculators all over the internet. IIRC about 13% for 35s depends on exact tire size. so the calc goes like this:
mileage driven x 1.13(tire size correction) = actual mileage / gallons used= mpg.

That's exactly what I was saying; however, I think the correction factor correlates to the tire size calibrated for the vehicle.

 

[Dirtymaxx03]

The speedometer is not calibrated for 35's. You would need to calculate the difference of revolutions per mile to determine how much further you are actually traveling per tank. Off the top of my head, just a guess, it would involve the difference in circumference of the two tire sizes, RPM's etc...sounds like a headache of conversions.

OR........

You simply base it on percentage. Not sure if this is correct. My 35's are actually 34.8" tall and smaller tires are 32.8". That's a percent difference of 5.75. Let's say I get 350 miles to one tank (23 gallons) . That's 15.2 mpg. Given the percent difference, I actually traveled 370.1 miles. That's 16.1 mpg. A difference of 1.1 mpg error haha. May not sound like a lot but it certainly adds up.

Or, you let EFI Live do all the math. You simply enter the displayed speed, then use a gps to confirm the actual speed, and enter that where it says actual speed. Then you press a button and its all fixed. Amazing stuff.
Im willing to bet your problem is that your tires are not calibrated

 

[jonathancasey19]

Or, you let EFI Live do all the math. You simply enter the displayed speed, then use a gps to confirm the actual speed, and enter that where it says actual speed. Then you press a button and its all fixed. Amazing stuff.
Im willing to bet your problem is that your tires are not calibrated

I do not own EFI software. My tuner lives 3 hrs away. I change tires multiple times per year. It's more feasible to know said calculations.