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6.0 performance / fuel economy questions


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Long story short, I’m not thrilled with my 10mpg truck. It is a 2015.5 CCLB 3500 SRW with a 4” Rancho lift and 35” Toyo MT’s. I realize this is a lot of truck to push down the road so I’m not complaining, just wondering if some mods will be worthwhile or if I’m not going to see the results I’m looking for.

 

basically, I’d be quite pleased if I could turn this into a 13+mpg truck, and gain some power.

 

my ideas are first and foremost a Blackbear tune, exhaust, mild cam and I’d go as far as a supercharger if it would in fact boost MPG’s to a measurable extent.

 

Some will be urged to say just to get a Duramax, I’ll disclaim that I do not want one. Any diesel newer than 2007 not going to find a home in my garage.

 

So with these mods would I simply be pissing into the wind, or are there worthwhile gains to be found? There is always the option of leaving it stock and stop fussing about MPG’s.

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Drop the lift, go to stock size tires will be the only thing that will make a noticeable difference.

 

Cam and supercharger will likely drop mpg. Tune might help some, but I can't say it'll pay off, other than fun factor.

 

Parts are expensive, and fuel is pretty cheap by comparison.

 

I will say the difference in stock size vs 35" tires can be a pretty significant savings every 50,000 miles.

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Re gear for the tire size. 4.56 or 4.88 without calculating will get you back to stockish mpg to compensate for the tire size. A good custom tune will gain you some HP.  A good truck/ torque cam will gain you more HP and TQ witch in turn with a proper tune and gears could result in better than Stock MPG pending you can keep your foot out of it.  A supercharger would also give you more Power across the board and in turn with gears and a tune also probably get you back to stock or better mpg.  All these will help as the engine will have to work less to get the truck moving..  Its only $$$    Only problem is wit all this the truck becomes more fun to drive so then MPG go down. LOL

 

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Maybe I'm wrong but I doubt that some gears and a tune would help with his mpg. It will restore acceleration and result in better overall driveability but not increase mpg  The truck is higher and the wheels are heavier so it will burn more gas to get it going and keep it at speed.  You want to play you have to pay.  

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Maybe I'm wrong but I doubt that some gears and a tune would help with his mpg. It will restore acceleration and result in better overall driveability but not increase mpg  The truck is higher and the wheels are heavier so it will burn more gas to get it going and keep it at speed.  You want to play you have to pay.  
It might get some of it back, because the driveline would have to work less to get the rig rolling, but you would never get it all back.

Besides, it would take a LONG time to offset the cost of the gear install with the minimal mpg gains (if any).

2012 2500hd 6.0l CCSB 4wd



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13 hours ago, 2016HD said:

Re gear for the tire size. 4.56 or 4.88 without calculating will get you back to stockish mpg to compensate for the tire size. A good custom tune will gain you some HP.  A good truck/ torque cam will gain you more HP and TQ witch in turn with a proper tune and gears could result in better than Stock MPG pending you can keep your foot out of it.  A supercharger would also give you more Power across the board and in turn with gears and a tune also probably get you back to stock or better mpg.  All these will help as the engine will have to work less to get the truck moving..  Its only $$$    Only problem is wit all this the truck becomes more fun to drive so then MPG go down. LOL

 

Sorry, but this is what you call "throwing good money after bad."   The lift and larger tires cause aerodynamic issues, increased rolling resistance, and heavier rotating weight and nothing is going to change that.  It simply takes more BTU's, calories, joules, whatever term you want to use, to accelerate or maintain speed in a lifted truck with big tires than it does in a stock truck.  

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6 hours ago, i82much said:

Sorry, but this is what you call "throwing good money after bad."   The lift and larger tires cause aerodynamic issues, increased rolling resistance, and heavier rotating weight and nothing is going to change that.  It simply takes more BTU's, calories, joules, whatever term you want to use, to accelerate or maintain speed in a lifted truck with big tires than it does in a stock truck.  

Hence why i Said you may get better mpg and or back to stock like etc.   If you want to pay you gotta pay as has been stated. And im sorry but i have modded many things in my life. And can tell you that with the right combination of parts and drive train you can get stock like mpg and sometimes better. Even with the lift and bigger tires!!  Its possible. He asked for opinions and i gave mine!!!!  Its not my money.  Will you gain the money spent back in MPG   NO> but it will be a more fun truck etc..  

 

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i cannot see how anyone could ever get the same mpg on 35's and a 4 inch lift as they could at stock height with 32's, short of replacing the gas engine with a diesel. which, by the way, has more btu's per gallon than gas.  

 

personally, i think a lot of the mpg claims on the internet are either calculation errors or outright bs.  so if you read about a guy with 37's that was getting 9 mpg and claims he shot up to 11 with a tune, realize that guy probably also tells everyone at the bar that he is an army ranger with a ten inch choad.

 

 

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I have not had my speedometer recalibrated, but by GPS I am out about 5% so I factor that in when I calculate MPG’s. Fact is this truck is 11.5mpg highway at best, and 9-9.5 around town. Before the lift and bigger tires I had a couple of 15mpg tanks hwy driving, around 11-12mpg around town.

 

The lift and tires are here to stay, so I realize gaining any MPG’s back is not going to be easy. Sounds like a Blackbear tune should be my first step, and I’ll consider gears if the cost is reasonable. Being that I’m only out 5% I don’t expect returning to stock final drive is going to be a game changer, but maybe if I go one step further it will help out the sluggishness that the big wheels/tires have caused.

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Gears will help with the sluggishness, but their importance for fuel economy is vastly overrated.  You will never come even close to getting your money back in fuel economy for a regear.

 

The tune will help somewhat with the sluggishness, maybe a smidge with the fuel economy.  But, if you are going to keep the lift and tires, your truck is what it is for the most part.  

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