Fuel Mileage With Intake, Exhaust, & Programmer

redjewel2ss · April 4, 2011

yesterday, i decided to take the Diablosport Trinity i have out of my Camaro, have the Camaro dyno tuned, and use the programmer in my Silverado. average fuel mileage was 17.0 mpg mix of city/highway. at 70 mph i was getting about 19-20 mpg on flat road. after i installed the 87 octane tune on my programmer, i took it out for some testing. i was getting 22 mpg at 70 mph!

i ordered a K&N 63 Series intake; almost went with the Volant powercore, but i read on here and elsewhere the volant box doesn't seal too well. i wanted a sealed box with a polyethylene tube because we get really hot summers here, i do a lot of highway driving, and it is also very dusty. also ordered Corsa DB Series cat-back exhaust, single side exit. i decided on the Corsa because of their "reflective sound technology" with zero drone while cruising and big sound when you stomp on the gas. i've had flowmaster and magnaflow on vehicles before and didn't like the cabin noise they created. i got the intake for $284 and the exhaust for $517 with free 2 day shipping from Amazon.com. not to bad considering the intake was $600 and headers/exhaust was $2000 on my camaro!

my main question is:

for those of you that have a similar combo (intake, cat-back exhaust, programmer with 87 octane tune) what kind of fuel mileage are you getting mixed city/highway, and also how much just on the highway?

i also ordered the steering wheel w/ audio controls, and Universal Home Remote roof panel, and Katzkin leather in black w/ dove tail grey perforated inserts and grey stitching. i'll post a new thread once i'm done with each thing!

dlstewart01 · April 4, 2011

You will not want to hear this, but I have the Diablo, a cold air intake and a Corsa exhaust. The absolute best mileage I ever got was when it was STOCK. And I have had this set up for 5 years. But the driveability is so improved I would not go back to stock.

You need to run several tank fulls over the same conditions and hand calculate the MPG dividing gallons used into miles traveled to get any meaningful numbers.

redjewel2ss · April 4, 2011

You will not want to hear this, but I have the Diablo, a cold air intake and a Corsa exhaust. The absolute best mileage I ever got was when it was STOCK. And I have had this set up for 5 years. But the driveability is so improved I would not go back to stock.

You need to run several tank fulls over the same conditions and hand calculate the MPG dividing gallons used into miles traveled to get any meaningful numbers.

what diablo tune are you running? 87, 93, or custom? i'm hoping it is a little different case with mine being a 2010, and yours being a 2005... not sure how much things have changed besides the transmission and gears between the 2 models. i know a lot of people say they get worse gas mileage because they would stomp on the gas more, but i have a sports car to drive if i want to go fast, if anything i might baby the truck a little more at first.

i'm going to wait a few weeks before installing the intake and exhaust so that i get about 1000 miles on the new tune so i get a comparison between 100% stock vs. programmed vs. programmed, intake & exhaust.

dlstewart01 · April 4, 2011

I have ran both 87 and 93. I sent my tuner back to Diablo to have it updated to the the latest specs. I can now data log and make all the adjustments.. Like I said the power and driveability (mine tunes the transmission) is so much better I would never go back. I personally don't think the MPG will improve much. If it were that simple GM would do it to meet the required cafe numbers.

have a good one.

redjewel2ss · April 5, 2011

i got on it while getting onto the highway today... chirped the tires shifting from 2nd to 3rd

that never happened before!

redjewel2ss · April 7, 2011

alright, i got the intake on last night! it looks almost like it should have been there from the factory IMO! the quality of the tube is like nothing i've seen before, it is thicker and feels more durable than the stock tube. i didn't realize there was a velocity stack or how big the filter was really going to be! the filter looks like it belongs on a diesel its so big!

preliminary fuel mileage results are as shown:

100% stock, 70/30 highway/city driving - 17.0 mpg

Diablosport 87 octane tune only, 70/30 highway/city driving - 17.9 mpg (this was after 500 miles of driving, with no adjustment to the tune and the exact same route i always take to work and back)

i'll have some mileage results with the intake installed in the next week, and i will be installing the exhaust after that. for now here is a pic of my dirty engine bay with the new intake:

kdixer · April 7, 2011

If tuners can recalibrate the fueling, they can easily change parameters that the ECM uses to calculate mpg. I recommend hand calculating you results. The whole point of a custom tune is to compensate for any mis calibrations various sensors may have. This recalibration should definatley effect the accuracy of the mpg readout on the DIC.

redjewel2ss · April 17, 2011

after a couple weeks and about 500 miles with just the intake on, i decided to go ahead and install the new Corsa exhaust. installation was a breeze! toughest part was using a hack saw to cut the stock headpipe so the system could be removed easier. the new sound is great! although it isn't quite as loud as my Camaro (which has long tube headers and muffler delete), it does have a nice deep tone that isn't raspy and zero drone as advertised.

so the verdict with just the intake installed:

100% stock, 70/30 highway/city driving - 17.0 mpg

Diablosport 87 octane tune only, 70/30 highway/city driving - 17.9 mpg (this was after 500 miles of driving, with no adjustment to the tune and the exact same route i always take to work and back)

Diablosport 87 octane tune, K&N 63 series intake, 70/30 highway/city driving - 18.0 mpg

not much, just 0.1 mpg, i'm still getting between 22-23 inst mpg's on the highway according to the DIC... we will see how it goes with the exhaust on, and after about 500 miles, i will adjust the fueling on the tune to optimize the mileage.

redjewel2ss · April 17, 2011

they don't mess with how the computer calculates fuel mileage. what i meant when i said adjust the fueling, i meant you can adjust the "injector slope" with the tune to optimize the Long-Term Fuel Trim. just a fancy way of saying, it adjust how much fuel is being delivered to the engine under light load. you can also adjust the "WOT Fuel" at low, mid, and high RPM ranges to optimize the air-fuel ratio, so that you get maximum horsepower & torque when you want to stomp on it. none of this changes the way the computer calculates mpg's. and yes i do double check the computer's calculations with my own by comparing it to the miles i've driven and the amount of fuel i've filled up with.

the only way to change how it calculates mileage is by installing different sized tires or taller gears... but then you can recalibrate it with a tuner so that it is accurate again... but i do not have different sized tires or taller gears.

If tuners can recalibrate the fueling, they can easily change parameters that the ECM uses to calculate mpg. I recommend hand calculating you results. The whole point of a custom tune is to compensate for any mis calibrations various sensors may have. This recalibration should definatley effect the accuracy of the mpg readout on the DIC.

Doug_Scott · April 17, 2011

Can't see where you say what engine you have, but, if you got a chirp from 2nd to 3rd it can't be the 4 speed trans, so you must have a 5.3 with the 6 speed.

My 4.8 with 4 speed, Volant CAI and 4.10 gears got 24.6 mpg a few weeks after getting a blackbear tune on a 100% hwy tank of 89 octane, figured by hand, not by DIC, driving with cruise at 102km/h for 672km nonstop (we can do that in Canada, and not even leave the province). Standard roads with regular elevation changes. Was driving from Ajax to Thunder Bay. That got me to the halfway point, did not bother checking after that on that trip. Was so happy with the near 25 I did not want to spoil it by verifying on back to back tanks.

TheGreekIndian · April 17, 2011

you should try the throttle body spacer... see how that works for ya. not to expensive..

http://www.gm-trucks.com/forums/index.php?showtopic=130105

redjewel2ss · April 18, 2011

Can't see where you say what engine you have, but, if you got a chirp from 2nd to 3rd it can't be the 4 speed trans, so you must have a 5.3 with the 6 speed.

My 4.8 with 4 speed, Volant CAI and 4.10 gears got 24.6 mpg a few weeks after getting a blackbear tune on a 100% hwy tank of 89 octane, figured by hand, not by DIC, driving with cruise at 102km/h for 672km nonstop (we can do that in Canada, and not even leave the province). Standard roads with regular elevation changes. Was driving from Ajax to Thunder Bay. That got me to the halfway point, did not bother checking after that on that trip. Was so happy with the near 25 I did not want to spoil it by verifying on back to back tanks.

yeah, i have a 5.3 with the 6 speed and it's either 3.08 or 3.23 gears, i'm not sure exactly which ones but i will find out this afternoon when i take it to the dealer for my service airbag light.

you should try the throttle body spacer... see how that works for ya. not to expensive..

http://www.gm-trucks.com/forums/index.php?showtopic=130105

i'm still not sure about these things. i don't like the whistling sound they make, and i'm not convinced on their advertised HP gains. 2 mpg's isn't worth the annoying sound when i'm on a long road trip; from what i've seen so far with this new exhaust, the road noise is still as quiet as stock. if it was a 10 mpg difference then i would definitely get one, in fact more people would be praising them than bashing them!

my buddy put one on a v6 f-150, and i always made fun of him because it sounded like his belt needed to be replaced!

travishale84 · April 21, 2011

i have had two TBS on my sierra's. the red poweraid spacer made a whistle at partial throttle, and it wasnt even noticable with my K&N intake on it. you definately cannot hear it with the windows up.

i currently have the JET TBS and it has ZERO whistle. my miles wend up .5 mpg consistantly since i have installed it. i live in Vermont and everywhere i go there are steep up hills, so mileage with trucks stinks.

beecha91 · April 22, 2011

Glad to see you made over to the site Ryan. I plan on doing a diablosport for my setup with the volant and 3 inch muffler back exhaust. Should make a difference hopefully..

Grumpy Tooch · May 6, 2011

i have had two TBS on my sierra's. the red poweraid spacer made a whistle at partial throttle, and it wasnt even noticable with my K&N intake on it. you definately cannot hear it with the windows up.

i currently have the JET TBS and it has ZERO whistle. my miles wend up .5 mpg consistantly since i have installed it. i live in Vermont and everywhere i go there are steep up hills, so mileage with trucks stinks.

did you have a problem with the neck on top of the water pump being in the way when trying to instal the TBS? I have a 06 Sierra 2500hd and the dam thing is in my way from installing the TBS.