6.0 performance / fuel economy questions

i82much · April 13, 2018

2 hours ago, Camstyn said:

Yeah I figured as much. I’m ok with it, I just like to tinker with things and try to improve them. I knew this truck would be thirsty when I bought it so I accept it for what it is.

The only way you save money with a 6.0 is 20 years from now when you are still driving the same truck!

Over the long haul, you won't do better than a 6.0. Sooner or later, something on a diesel is going to break and cost all kinds of money. Injectors, fuel system, emissions, transmission, it all costs ridiculous amounts of money.

1/2 tons will probably have AFM issues while your 6.0 is still going strong.

The 6.0 probably isn't going to give out on you in your lifetime, and the 6L90 won't cost much to repair if it does. So if you like your truck, you're in luck. Just keep driving and at some point you'll have gone many, many years without a truck payment or a major repair bill. At that point, all those expensive fillups won't seem so bad!

Edited April 13, 2018 by i82much

mjm-1957 · April 14, 2018

Couldn't have said it any better.Truck is bullet proof, no direct injection, no AFM, cast iron block, real cooling fan,no electric power steering rack ,etc etc etc.I work in a GMC Buick dealer and we never see any problems with the 2500 or 3500 HD's with the 6.0's. The diesels come in every day for check engine lights, coolant leaks, turbo charger problems, def heater problems, egr cooler codes or leaks, glow plugs, nox sensors and on and on and on. Can't imagine being happy being without your brand new diesel truck while it spends days at the dealer trying to get fixed.I figure my 2017 2500 HD with 6.0 and 6l90 will probably be around trouble free for along time and if it does need anything I can fix it myself.

SierraHD17 · April 14, 2018

Plus these heaps are cheap being the same engine and trans for over 10 years now. I got a 50000 mile pullout L96/6L90E and t case for 2500 bucks from a 2015 2500. Who cares if my 17s blows up lol.

Big Whiskey · April 16, 2018

Yep, as stated, your lift and 35's are the main culprit. The price of cool isn't cheap, haha. And, all of those things you mentioned (tune, gears, supercharger, etc.) will cost way more than any gas savings you'll gain from installing them. You'll never increase the MPG's enough to justify the cost. However, those things will drastically increase the SMILES per gallon...which are more important than miles per gallon anyway!

free88 · August 20, 2018

On 4/13/2018 at 12:24 PM, Camstyn said:

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.

The caution with the tune route is that you are literally paying someone to tell you what you want to hear. You ask them for more MPG, swipe your credit card, and they tell you your wish is granted. You ask them for more HP, swipe your credit card, and they tell you your wish is granted. And so on. There is a huge market for this, and they are happy to grab every dollar they can selling dreams. Everyone wants to believe that a custom tuner has figured out something that the OEM's with their teams of engineers with a combined 100's of years of experience, 100's of millions of dollars invested in wind tunnels, dynos, metering equipment, software development, hardware development, etc., could not figure out. Gimmie a break. All the OEM's are trying to give you the best performing, longest lasting engines they can. Its not just a slogan. They are not holding back, and its a fierce battle for supremacy. If you changed tire size or gear ratio or whatever and you simply need to re calibrate for that, well, thats fine. But I would never let one of these hacks change anything else. It is impossible for them to do what they say they can do. Things like "economy mode" is most likely just an on-the-fly recal that will trick your DIC into showing better MPG's than you are actually getting and a transmission profile remap. The psychology of being in "economy mode" will cause you to take it easy, thus maybe even yielding actual results. Rest assured, its nothing they did. Its all you. "Performance mode" is same deal. The DIC gets another recal and the transmission profile is remapped. Your mind does the rest.

kstruckcountry · August 20, 2018

The caution with the tune route is that you are literally paying someone to tell you what you want to hear. You ask them for more MPG, swipe your credit card, and they tell you your wish is granted. You ask them for more HP, swipe your credit card, and they tell you your wish is granted. And so on. There is a huge market for this, and they are happy to grab every dollar they can selling dreams. Everyone wants to believe that a custom tuner has figured out something that the OEM's with their teams of engineers with a combined 100's of years of experience, 100's of millions of dollars invested in wind tunnels, dynos, metering equipment, software development, hardware development, etc., could not figure out. Gimmie a break. All the OEM's are trying to give you the best performing, longest lasting engines they can. Its not just a slogan. They are not holding back, and its a fierce battle for supremacy. If you changed tire size or gear ratio or whatever and you simply need to re calibrate for that, well, thats fine. But I would never let one of these hacks change anything else. It is impossible for them to do what they say they can do. Things like "economy mode" is most likely just an on-the-fly recal that will trick your DIC into showing better MPG's than you are actually getting and a transmission profile remap. The psychology of being in "economy mode" will cause you to take it easy, thus maybe even yielding actual results. Rest assured, its nothing they did. Its all you. "Performance mode" is same deal. The DIC gets another recal and the transmission profile is remapped. Your mind does the rest.

Yes, tune to increase mileage is a pipe dream. I'm sure there are some "hacks" out there, but I have never heard bad things from someone working with a reputable shop.

What you don't seem to realize is that the stock tune is designed within a specific set of conditions. When people do things like change intake, exhaust, put on a supercharger, etc, the stock tune generally is not capable of fully responding to these changes. Additionally, some people just don't like the sluggish response of the General's transmission tuning, along with gear hunting, waiting too long to upshift when in lower gears at lower throttle, etc.

I'm sure you've driven lots of tuned vehicles, though, so you probably know what you're talking about. I have only put 80,000 miles on my rust bucket since it was tuned.

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SierraHD17 · August 20, 2018

No what custom tuners dont need to worry about is things like EPA test requirements, drivetrain warranties, fuel octane levels, etc. The L96 has a lot left on the table from the factory simply from those 3 conditions alone. Economy I won't say will improve but performance.... that's real. There is an easy 30 hp and 30 ft lbs hidden in tuning alone on these trucks...

But hey we that tune are all just stupid hacks so what the hell do we know... lol.

Edited August 20, 2018 by SierraHD17

KARNUT · August 20, 2018

I’ve gotten gains out of all tunes since 2001, gas and diesels. Tunes from the factory are general, custom tunes are custom tailored even caned tunes. Saying other wise is lying.

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free88 · August 20, 2018

1 hour ago, kstruckcountry said:

Yes, tune to increase mileage is a pipe dream. I'm sure there are some "hacks" out there, but I have never heard bad things from someone working with a reputable shop.

What you don't seem to realize is that the stock tune is designed within a specific set of conditions. When people do things like change intake, exhaust, put on a supercharger, etc, the stock tune generally is not capable of fully responding to these changes. Additionally, some people just don't like the sluggish response of the General's transmission tuning, along with gear hunting, waiting too long to upshift when in lower gears at lower throttle, etc.

I'm sure you've driven lots of tuned vehicles, though, so you probably know what you're talking about. I have only put 80,000 miles on my rust bucket since it was tuned.

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The stock air intake, for example, is already high performance caliber on just about every single vehicle currently in production and certainly true of these trucks. Going to an aftermarket unit that flows more is of no consequence to an otherwise stock or near stock engine. The stock unit offers waaaay more than enough flow, so whats another "a" in way. Its nothing. The stock exhaust, too, is already high performance caliber on just about every single vehicle currently in production and certainly true of these trucks. Going to an aftermarket unit that may flow better is of no consequence. Individually or both combined will not make any difference, and if it does it will certainly be within the adaptive capabilities of the code to realize the extra power. I am sure that code is tested from totally clogged air filter to no air filter and everything in between. You telling me an aftermarket air intake will flow more than the stock intake with no air filter? I dont think so. Same with the exhaust. I am sure they are testing everything from the exhaust fell off the truck to a tailpipe under water, and the code can deal with all of it. . Supercharger is a different story. That is a significant modification.

Changing the transmission mapping is not the same as increasing the HP/TQ or power curve of the engine. Two totally different things. These changes are real, though almost always for the worse. The OEM already mapped it the best way. Anything else is, well, not the best way. Good luck with that. But, what I want to highlight here, is that transmission remapping does not increase HP/TQ of the engine.

I dont know what I am talking about because I have driven whatever miles on a tuned truck. I know what I am talking about because I am a control systems engineer with multiple engineering degrees, decades of experience, and the skill set to code every PLC and HMI in your truck from scratch. This is what I do. But, nah, Im sure you know better cause you paid a guy to tune your truck once. I love the internet.

free88 · August 20, 2018

1 hour ago, SierraHD17 said:

No what custom tuners dont need to worry about is things like EPA test requirements, drivetrain warranties, fuel octane levels, etc. The L96 has a lot left on the table from the factory simply from those 3 conditions alone. Economy I won't say will improve but performance.... that's real. There is an easy 30 hp and 30 ft lbs hidden in tuning alone on these trucks...

But hey we that tune are all just stupid hacks so what the hell do we know... lol.

If there was an extra 30/30, they'd give it to you. They must comply with emissions standards, however. That is not the OEM's fault. They must produce engines capable of at least some flexibility with fuels/octane, temperature variance, humidity, component degradation over time, etc. They must produce trucks that will last and perform well enough to the end. These are not optional things.

Look, I get it. You want to protect your livelihood. Selling snake oil can be really profitable. Especially in this case where you are spending zero research dollars, offer no warranty to replace the one you just broke, and are not subject to independent verification of your claims. OEM HP/TQ claims have to be repeatable and independently verifiable and backed by a warranty. It must be nice to not have to meet the same standard. So, yes, you are just another hack. You mind as well say there another 100/100 in these trucks. Who cares, right? Its not like anyone can hold you to that. You just take their money and go about your day.

KARNUT · August 20, 2018

Tunes are snake oil that’s good. I agree that in later years there’s been less a a need for intake and exhaust modifications even with mild tunes. The gains with tunes are real and reliability doesn’t suffer with reasonable use. The real gains are with turbo engines gas or diesel, up to 100 HP in some cases. Reliability is up to the user like anything else. Every diesel I’ve owned was at least tuned and pulled loads too. I have a gas blown truck that’s 27 years old with one refresh.

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free88 · August 20, 2018

1 hour ago, KARNUT said:

I’ve gotten gains out of all tunes since 2001, gas and diesels. Tunes from the factory are general, custom tunes are custom tailored even caned tunes. Saying other wise is lying.

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That may have once been true. In the carburetor days, certainly. Mostly true in the early FI days. Past 10-15 years, not really. The OEM codes are highly adaptive and can compensate a great deal. The hacks dont want you to know that, because it puts them out of business. They want you to believe that changing literally anything needs a new tune. 93 octane, new tune. New air filter, new tune. New exahust, new tune. Its false. The OEM code is adaptive enough to deal with all of that on its own without any modification. They have made big business out of this, though, haven't they. So many people willing to through money at this and not demanding a shred of proof in the end. Its the perfect scheme.

I am going out with this final comment. If you are still insisting on burning your cash on a custom tune (for simple mods like CAI, exhaust, etc.), get independent verification testing done before and after. Otherwise, you have no idea what you actually got (if anything at all). Any ass clown can promise you the world, take your money, and call it a day. Get the hard numbers to back it up. If you do this, I promise it will be the last time you throw money at this.

Edited August 20, 2018 by free88

free88 · August 20, 2018

1 minute ago, KARNUT said:

Tunes are snake oil that’s good. I agree that in later years there’s been less a a need for intake and exhaust modifications even with mild tunes. The gains with tunes are real and reliability doesn’t suffer with reasonable use. The real gains are with turbo engines gas or diesel, up to 100 HP in some cases. Reliability is up to the user like anything else. Every diesel I’ve owned was at least tuned and pulled loads too. I have a gas blown truck that’s 27 years old with one refresh.

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There will be mods that will require custom tuning. You will simply have no choice. A supercharger or a turbo being two of them. For CAI, exhaust, etc., nope.

KARNUT · August 20, 2018

There will be mods that will require custom tuning. You will simply have no choice. A supercharger or a turbo being two of them. For CAI, exhaust, etc., nope.

Your missing the point, you get the gains with a tune without changing those. There’s plenty of documentation on that, some here on this website.

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free88 · August 20, 2018

1 minute ago, KARNUT said:

Your missing the point, you get the gains with a tune without changing those. There’s plenty of documentation on that, some here on this website.

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No, Im not. If it can be done it would have already been done by the OEM. You did not figure out something they missed. The competition is fierce among them (and has been forever), and they are looking to give you everything. They are totally not looking to leave 5, 10, 15 HP on the table just because it makes them feel good. And at no additional hardware expense? Hell no. At the end of the day brochures still sell trucks, and they want the prettiest numbers they can print in those brochures.