anoother mpg thread
#12
11-16-2015, 07:19 PM
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If your only engine modifications from stock are the ones you've listed, I have two thoughts:
1) Stop adding octane booster and stop using 93 octane gas. Gasoline is a mixture of hydrocarbons. The "octane rating" at the pump is not a measure of the octane in the gas; it is actually the Knock Resistance Index which is measured in units called "octanes" because octane is one of the hydrocarbons in gasoline and has high resistance to pre-ignition. High octane gas is not higher quality gas. It does not burn cleaner nor does it produce more energy, it is simply more resistant to preignition due to its higher flash point. It is more expensive due to additional fractionation procedures to yield a different mixture of hydrocarbons. Sports cars and race cars use high octane gas because their high compression engines (11:1 to 16:1) need gas that will not spontaneously ignite under the higher pressure before the spark plug fires.
Your engine has a 8.9:1 compression ratio and was designed to run on gas with a minimum octane rating of 87. Adding octane booster to 93 octane gas is giving you around 108 octane gas (could be more or less depending on brand) which is far, far outside of what your engine was designed to run on. Your "super gas" is killing your fuel economy because it doesn't burn well in your low compression engine. Your 180 degree thermostat lowers the temperature of the engine which adds to this effect.
The next time you fill up your tank, run it as close to empty as possible, then fill it up with 89 octane, don't add anything, and let us know how it goes.
2) You have the off road package so maybe you're running tires which are very large (heavier), very wide, or have very aggressive tread. All three of those things increase rolling resistance which will hurt fuel economy. What tires are you running?
1) Stop adding octane booster and stop using 93 octane gas. Gasoline is a mixture of hydrocarbons. The "octane rating" at the pump is not a measure of the octane in the gas; it is actually the Knock Resistance Index which is measured in units called "octanes" because octane is one of the hydrocarbons in gasoline and has high resistance to pre-ignition. High octane gas is not higher quality gas. It does not burn cleaner nor does it produce more energy, it is simply more resistant to preignition due to its higher flash point. It is more expensive due to additional fractionation procedures to yield a different mixture of hydrocarbons. Sports cars and race cars use high octane gas because their high compression engines (11:1 to 16:1) need gas that will not spontaneously ignite under the higher pressure before the spark plug fires.
Your engine has a 8.9:1 compression ratio and was designed to run on gas with a minimum octane rating of 87. Adding octane booster to 93 octane gas is giving you around 108 octane gas (could be more or less depending on brand) which is far, far outside of what your engine was designed to run on. Your "super gas" is killing your fuel economy because it doesn't burn well in your low compression engine. Your 180 degree thermostat lowers the temperature of the engine which adds to this effect.
The next time you fill up your tank, run it as close to empty as possible, then fill it up with 89 octane, don't add anything, and let us know how it goes.
2) You have the off road package so maybe you're running tires which are very large (heavier), very wide, or have very aggressive tread. All three of those things increase rolling resistance which will hurt fuel economy. What tires are you running?
Excellent post
#13
11-16-2015, 10:47 PM
#15
11-18-2015, 04:00 PM
And ditch the mileage tune. Stick to the other 3. The mileage tune actually just pulls timing worse than factory death flash and leans it out slightly BUT now you have to lay into the throttle to have any usable power.
Stock with only flowmaster 50 catback I could just eek out 19.5 doing 63mph over long flat roads with little to no wind. With m1 intake manifold, superchips 91 octane tune, free flow magnaflow muffler I was getting about 14-16 on the interstate doing 70-75 and getting up to speed with a very heavy foot. This is all with the same Goodyear Wrangler SilentArmour tires in stock 245/75/16 size.
Then I bumped up to 265/75/16 ProComp MT2s, added shorty headers, FlyinRyan tuning, shift kit, 52mm throttle body, and more lead in my foot and I average 9 with an incorrect speedo. At 70 on the speedo I'm actually doing 75 so I'm not racking miles QUITE as quick as I should be. Prob sitting closer to 11 average.
Stock with only flowmaster 50 catback I could just eek out 19.5 doing 63mph over long flat roads with little to no wind. With m1 intake manifold, superchips 91 octane tune, free flow magnaflow muffler I was getting about 14-16 on the interstate doing 70-75 and getting up to speed with a very heavy foot. This is all with the same Goodyear Wrangler SilentArmour tires in stock 245/75/16 size.
Then I bumped up to 265/75/16 ProComp MT2s, added shorty headers, FlyinRyan tuning, shift kit, 52mm throttle body, and more lead in my foot and I average 9 with an incorrect speedo. At 70 on the speedo I'm actually doing 75 so I'm not racking miles QUITE as quick as I should be. Prob sitting closer to 11 average.
#17
12-01-2015, 12:42 AM
#19
12-09-2015, 03:12 AM
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#20
12-11-2015, 04:23 PM
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You'll probably get better mileage out of the towing tune -- it often does better than the MPG tune and doesn't hobble the engine. I don't often get an opportunity to check fuel economy, but the last time I did the truck weighed in at right around 6600 pounds, was rolling at about 3000' in elevation in overdrive on 31" tires at 65MPH and showed 15.9MPG on the Superchips towing tune over the course of about 110 miles. It's likely better now that I've stepped back down to 245's (and normally roll at around 6000 pounds GVW) but there's no point my recording numbers except on long road trips which haven't happened since the tire change.