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Intake, Exhaust, Tune Fuel Economy Results!


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I decided to compare my fuel mileage after each separate performance addition to my truck. i first started with a new diablosport 87 octane tune, drove 500 miles, installed a new K&N 63 Series intake, drove 500 miles, installed a new Corsa DB Series cat-back exhaust, drove 500 miles, and then adjusted the tune to optimize fuel trims, and drove another 500 miles.

 

after each stage, i compared the DIC's average MPGs to my own calculations of fuel used vs. the trip odometer. the DIC average MPGs were spot on with my own calculations, so the tune could not possibly be altering the computer's calculation as someone speculated before. i then reset the MPGs, the trip odometer, and the fuel used before adding a new part.

 

my driving habits are 80% highway, 20% city driving. it's pretty rural out here, and work is 18 miles from home, with mostly highway driving at 70 mph. i did go the speed limit the entire time. when accelerating i kept my RPMs at 2500 or less so the results would not be skewed.

 

on to the results:

 

100% Stock - 17.0 mpg average; on the highway @ 70 mph the DIC would read between 19 & 21 instantaneous MPGs

DiabloSport 87 Octane Tune - 18.0 mpg average; 20-23 instantaneous MPGs on the highway

Tune + Intake - 18.1 mpg average, 20-23 highway MPGs

Tune + Intake + Exhaust - 18.0 mpg average; 20-23 highway MPGs

Tune Optimized + Intake + Exhaust - 18.7 mpg average; 21-25 highway MPGs

 

so from these results, an intake and exhaust really do not improve fuel economy at all unless you adjust your tune to compensate for them like i did. my fuel trims with just the tune installed did not require any adjustments to the tune. the LTFTs were at -2%. when i was datalogging after the intake and exhaust were on, the LTFT's were +7%; which is a good indicator of the extra air flow. once i adjusted the tune to get the LTFT's between 0 & -2%, i gained an average of 0.7 mpg.

 

looking at this from an investment standpoint, the total cost for parts was $780; the programmer was free (gift). with gas prices at $3.75 per gallon, it will take 39,000 miles, or 2 years at my average of 19,500 miles per year, to payoff the parts. i intend on keeping my truck for at least 5-10 years, so if i save money in the long run, this is an OK investment.

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Wow nice write up. Not too many of us think of or are capable of doing such a test. Once again a tune is the best bang for the buck....

 

 

it definitely is... especially when you get it as a christmas gift :(

 

i got the new Diablosport Trinity in 2009 and originally used it on my Camaro, but decided to use it in my daily driver instead.

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  • 1 month later...

what would be the advantage of getting a diablosport tuner versus having justin over at black bear performance hook me up with a tune? cause i plan on doing this same thing for my 8.1L 2500HD

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what would be the advantage of getting a diablosport tuner versus having justin over at black bear performance hook me up with a tune? cause i plan on doing this same thing for my 8.1L 2500HD

 

None if you get the AutoCal device from Justin. :flag:

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