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Thread: Silverado 5.3 Gas Mileage
09-14-2012, 02:10 AM #1
Silverado 5.3 Gas Mileage
I just dropped a 5.3L engine into my Silverado and I'm shocked at the gas mileage I'm getting now. I get like 17-18 mpg while going 80. Is that normal? I have an intake, exhaust and bully dog programmer. My 4.8L that was originally in the truck was getting like 25 so I don't understand why it would be that big of a drop. I was just wondering if that was the normal mileage for you guys out there with the 5.3. Please help!
btw the engine was out of an 04 Silverado. and I have 3.23 gears in the rear end.
Last edited by Chad513; 09-14-2012 at 02:13 AM. Reason: added info'07 Chevy Silverado Classic
-Air Raid Throttle Body Spacer
-Bully Dog Triple GT Programmer
-3" Spindle Lift
-Blacked Out Rims
-Blacked Out Taillights
-2 Kicker CVT 12s
-Rockford Fosgate 6.5"
-500 Alpine Mono Block
-Pioneer 6.5" Touch Screen
-2 Boss Tweeters
09-14-2012, 02:21 AM #2
Well its a lil bigger motor with a lil more power, which will result in a drop of mpg and also going 80 with that motor means it needs more fuel which also results in lower mpg. so that is about normal.
2010 Silverado Z71
"Fueled by Haters"
TCS front box 7"-9" set at 8.5" | FTS coilovers(blue coil) with resis and FTS shocks with resis| 20" Fuel Off-Road Revolver Rims | 35x12.50 Nitto Trail Grapplers | Halo Projector Head Lights by Recon- Black | Led Taillights by Recon- Smoked | Dumped Straight pipe | Volant CAI | Ranch Hand Front Bumper | DiabloSport Trinity Programmer | Tow Mirrors with Turn Signal | Cervinis Ram-Air hood | 4.56 USA gears with tru trac locker | Longshot Lighting 6000k 55w low beam and 6000k 35w fogs HIDs | 7" lift leaf spring | Blue TCS traction bars
Future Mods: Long tube headers | Custom tune | Cam | Stall Converter
09-14-2012, 02:25 AM #3
It scares me lol. I have never seen that low of a number. Your truck is sick btw man. I just joined the Navy and am hoping to do lots of stuff to my truck when I go on leave.
09-14-2012, 02:28 AM #4
I can squeeze 20-21 assuming a flat highway doing 60-65. After 65 it starts dipping fast. 17-18 at 80 doesn't surprise me at all and sounds about right. I've toyed with the idea of dropping a 6.2 into mine at some point. I most likely won't, but if I did I'd expect a 10-20% drop in highway mpg just like you noticed going to the 5.3.
To Be Completed (Eventually):
6" BDS Suspension lift | KingShocks Front and Rear Coil Overs | 4.56 Gears | 35" A/Ts (TBD) | Cervinis 07-12 Silverado Ram Air Hood | Fab Fours Front Winch Bumper (CS07-H2051-1) | Fab Fours Full Size Rear Bumper (CS07-W1850-1) | RX-2 Series Main Grille (Black) | Line-x Bed and wheel wells | Skid Plates | Rizor Automated Tonneau Cover | Custom Bed Insert | RBP RX-3 Series Nerf Bars | Kenwood Excelon DNX9990HD | JL Audio Stealthbox (2x500RMS) | JL Audio HD 1200/1 Class D Mono Amp | JL Audio C5-653 Components (Front) | JL Audio C5-650 Components (Rear) | JL Audio Slash v2 300/4v2 Class A/B Amp
09-14-2012, 02:46 AM #5
chad- thanks man. its all deployment in that truck lol.
jeremy- i thought about a 6.2 as well, once its paid off i think i might hop up to it for the extra power.
09-14-2012, 05:31 AM #6
Chad: what rate did you get in the Navy? I was in the Navy myself. Also, I used to get 22-23mpg driving from Bakersfield Ca to Los Angeles, then I leveled my truck and bigger rims/tires and now i get 19 if I do it right lol. All I have is an intake (the mileage was done via the good ole math method instead of DIC)
09-14-2012, 07:46 AM #7
- Join Date
- Mar 2010
- Montgomery, Alabama
I have a '12 Ext Cab with 5.3 and 3.08 gears, a PCM for Less tune, K&N system, magnaflow single in, dual out and 20s on the ground. The absolute best mpg I can get on the highway, running an average of 80 mph, is 15mpg. It would be a miracle to get 18mpg at 80, in my opinion. BTW, I'm retired Air Force myself.
09-14-2012, 08:00 AM #8
corvetteOJ your best bet to help get milage up is new gears. having 3.08 with a 5.3 is causing you to run at a higher RPM which is killing your mpg and having 20s which are heavier is also killing it.. i had 3.42s when mine was stock and average just over 20mpg on the highway. but now that mine is lifted im soon to be running 4.56s...Also what did you do in the AF, im currently enlisted. just hit my 3 year mark in july and am on my 2nd deployment.
09-14-2012, 09:00 AM #9
- Join Date
- Mar 2010
- Montgomery, Alabama
I did 27 years in the Air Force, enlisted, retired CMSgt. The first half of my career (approx. 14 years) I was a crew chief on fighters, mostly F-4s. The second half (13 years) I was in PME, (Professional Military Education) at various positions, including Commandant for three years.
09-14-2012, 09:09 AM #10
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