Modifications to a new truck to increase MPG?
 

Hi, you are all probally bored to tears with my request, but what modifications can I make to a new 2008 Chevy Silverado 2500 HD that will legitimately increase my MPG - even just 1 or 2 MPG.

Please don't get too down on me for my choice of vehicles. My other car is a Subaru. The truck will only be driven when our needs require it. Probally will only put 4-7,000 miles on it any given year. We need a 3/4 ton truck, that is the bottom line. I would have gotten a hybrid 1/2 ton but it will not suffice. A deisel engine is not a good choice for our high altitude, very cold climate (often -34 in winter when starting vehicle, many weeks -20). There is no biodiesel available and pure vegi oil is not a viable option here.

I already employ the basic fuel economy recommendations and I ride my bike almost exclusively. (I can ride my bike to work and to run all my errands). I even have studded snow tires on the bike so I can get to ride in the winter when we have 4-5" of packed on the roads for 5 months of year. (At least for now).

I have been reading and looking at the various aftermarket products that one can add to their vehicle and am interseted in which of these are valid. Any comments, suggetions, advice etc is greatly appreciated.

CBARTISTS

poof well, when its gonan be that cold and snowy and slippery, i dont think much of anyhting is gonna help FE. pumping the tires up will help, and just driving and accelerating slow will help you the most i would think. is it manual or automatic? if its manual i would say coastign would help alot, auto i dont know if it would be such a good idea to be coasting then dump it into gear while on snow...never tried it so i cant say.

Are there any gearing swaps you might be able to make with the truck? I've seemed to notice gearing makes a big difference with such vehicles.

Welcome to the site!

Go slow. :-)

Do you need the power, or just the cargo capacity of the truck? If you don't need the power, consider a chip programmer that will let you select economy modes...and maybe even change the shift points.

cbartists -

Do you already have an engine block heater for cold starts?

Is this a good place for a fuel controller (or a stick-up)? You could have a thrifty "no load" mode for when you are driving the truck empty. Here is an example :

https://gotboostinc.com/electronics.html

This one seems to be on sale :

Apexi S-AFC 2 Fuel Controller - discontinued
https://gotboostinc.com/401-a907.html

I'm only showing the above because someone got it on sale :

https://www.saturnfans.com/forums/sho...98&postcount=6

It doesn't seem like any of them mention V8's specifically, but I would think that they support V8's because there are V8 tuner cars.

CarloSW2

The appropriate mods would depend on the type of driving you do (low speed around town or high speed in rural areas and freeways). For both types of driving; raising tire pressure up to max sidewall pressure (less rollng resistance), use the lowest weight motor and transmission oils allowed by your owner's manual (less engine/transmission friction losses), grill block (less aero drag and faster engine warmup),and employ the hypermiling driving techniques as discussed on this forum and at Cleanmpg.com.

For high speed driving, reducing aero drag is most important. How far you can go with it depends on what you use your truck for. You can start with underbody panelling (which can double as skid plates), smooth hub caps, rear wheel skirts, as these mods can reduce drag without adversely affecting the truck's utility. There are other aero mods (specially shaped bed covers, reshaped front end, etc) you could add to your truck to improve mileage but, depending on what you use the truck for, they could affect its utility to some degree. Take a look at pics of Phil Knox's Toyota T100 for ideas on extreme aero for trucks.

VO is possible, you just need a system designed to heat up the tank well at those temps. :thumbup:

A tonneau box cover will give immediate improvement at highway speed. Depending on your road conditions and hauling needs you might be able to use low rolling resistance narrower tires pumped to the side wall max, what tires are on the truck now? When you're not towing or hauling heavy loads you can blank off much of the grill in front of the radiator, or just hanging some screen material in front of the rad to keep bugs from plugging the vanes and to minimize rock damage so that your clutch fan is not kicking in as often helps. You probably don't have an electric radiator fan so you might consider one of those, a speed shop can set you up. If you don't do any towing you can get by with smaller side mirrors for some improvement at highway speeds. Some lightweight aluminum full length skid plates such as for 4x4 use can help smooth out the underside of the truck.

Using OEM specified lubricant grades but of a higher quality with an ester base component in the diff and engine will help, Redline, Amsoil, Motul, etc. If the truck doesn't have an instantaneous mpg readout a Scanguage2 that plugs into the OBD2 port will immediately show what the improvement in fuel economy is when driving 60mph instead of 65, or what the saving is for slow climbing a hill. Talking to a speed shop might give some ideas as they will have things like undersized pulleys for various components running off the fanbelt which can reduce parasitic engine drag, but most of those guys will first try to sell you on expensive intake mods and cat-back exhausts which won't help you at all in terms of economy.

Rather than taking someones word from a forum you'll want to research each improvement that can be done to determine if it will work in your application imo, but for something around a $1000 investment you could get your truck to 25 or better mpg I think, which is only a few percent above EPA ratings. Somewhere I've read that by 2011 OEM's will need to provide 30 mpg gasoline light trucks, but I had a 30 mpg or better truck 40 years ago although not to current emission standards.

Are you towing something heavy all the time with it?

Put 10% taller, but thinner tires on the rear. This will probably set off an error for ABS, but I think it would still work. If you don't want any ABS problem, then put equally taller tires on the front. Inflate as to max safe level.

Obviously you'll need to make sure you have clearance.

This effectively would change the gear ratio by 10%.

Since its a GM, a Hot Air Intake with a cold air flap that would open by pulling a manual choke cable might work to get you power when needed and efficiency when not. Instead of cutting up the original airbox, get an extra one to modify and swap it back to stock when you take it in for any warranty repairs.

When you change fluids, switch to as thin of synthetics you can get away with and keep the oil 1/2 qt low, but with a bigger filter.

As suggested above, reducing wind drag in the bed somehow should be up on your list.

I'm fairly sure that the 2500 HD is a 4x4 so you would need to keep the tires the same size on each corner, but as Bob says you may be able to go a size taller, look for LRR tires that have less revolutions per mile, the ones you have on now are likely about 685 revs/mile look for about 635 to 650. Several other things you could do is if it has automatic front hubs change those to manual, install air deflectors in front of each tire and modify the springs to lower the body from 2 to 4 inches. You could also look for the lightest weight LRR tires, lighter aluminum wheels if yours are steel and an aluminum rear drive shaft for some weight savings.

Have your dealership check the alignment as that can often be incorrect from the factory, and have them check for abnormal brake drag at the same time. Depending on your hauling needs you might even be able to source a factory look lightweight fiberglass box to replace the factory steel, as well as an aluminum rear bumper for some good weight savings. You might also look at the need to carry a spare tire.

You might even look at an electronic fuel cut-off governor to force you to keep the speed under a set limit, depending on hills in your drive.

Just reread your original post, definitely look at Motul Gear 300 75W90 differential oil, good to about -55C, I'd do some UOA's to confirm iron wear but if you have limited slip diffs you'll need to use thicker synthetic gear oils, Mobil 1, etc.

Motul Gear 300 75W90

YMMV ;-)

I wouldn't beat yourself up too much over your economy particularly if you are using your truck for truck-type tasks. None of our recommendations will produce much improvement if your use includes allot of towing a 10,000 lb trailer around for example. (Expect 8-9 MPG at best if that is the case.)

On the other hand, allot of highway travel without a trailer could see measureable benefit with a tonneau cover or canopy.

I would think that taller tires could also reduce mileage if this truck spends a lot of time at lower and varying speeds.

EPA for the 2500HD Vortec MAX 6.0L V8 is about 15city/19hwy mpg, so anything north of that is all good.

Unfortunately he never said WHY he needed a 3/4 ton 4x4 truck, or whether the miles on it would be city or highway, etc. If he's using it to go thru deep snow in the winter, none of these things are going to help much.

We will use the truck to carry our popup slide in camper made by Outfitter. It is an 8' unit that weights about 900 pds dry. I'm an artist, we travel to 6-7 art shows, mostly in the state so mountainous terrain. In fact, to leave here one must go over at least one mountain pass. Most travel will be in the summer. We will also pull a tiny trailer to the shows. Having a camper will provide us to a better experience at the shows. As well as a safer vehicle to get there. Right now we pull the trailer with our 91 Ford Econoline and use it to live out of at the shows. Not safe and horrible FE.

We'll use the camper for fun too, but in the winter I suspect it won't get driven much at all. Since we have the Subaru for highway miles and I ride my bike mostly.

I apprecaite all of the replies. I hope we can improve our mileage even just a 1 or 2 MPG.

It's too bad Chevy doesn't offer the 5.3 in the 2500 series. Actually, it's shameful because the 6.0 is much thirstier and is overkill for many applications that don't need tremendous towing capacity, especially ones like yours where you want the payload capacity but still want decent economy.

Aero drag and weight will be your 2 big issues. Most popups still stick up about a foot over the top of the cab and then arc up backwards from what you want like a boat hull IIRC. That won't be good for aerodynamics, nor will the exposed legs that stick out along the sides. I'm not sure if you could come up with some kind of fairing solution for it, but that would be a big step.

Your best best will be to leave really early and not exceed 50 mph and go even slower if possible. Also, every pound you take affects your mileage so it'll be a matter of loading in stuff based more on needs than wants.

While glancing around on a google for anyone that that might have found a cure for the 6 litre's thirst, I came across this:

"My Wife and I both have 2002 2500HD Suburbans with the 8100. We Both love the way the truck rides and performs. Not the wimpy 1500 soccer mom versions. November of 2006 was the last month to order a 2006 2500HD with the 8100. My dealer really screwed up by not letting me know. He could have sold two new trucks and we could have been 4 model years ahead of the game. Now we have trucks we cannot replace. I hope GM gets its head screwed back on straight and wises up. They had a truck that had no competitor."

Yes, his and hers maximum size, minimum mpg Suburbans! LMAO

Anyway 11 mpg x 2 is 22 mpg, right? LOL

Everyone in that forum was lamenting the loss of the 8.1 litre big block and that new suburbans only hold 4x7s not 4x8s.

Too bad a diesel wouldn't have worked. I don't see why not seeing as diesel has antigel additives, available block heaters and turbochargers to compensate for high altitude and cold weather. The 6.0 under load typically returns half the unloaded mileage on flatland conditions, and isn't all that much fun to drive in mountainous territory, according to 6.0 owners on another board I post to. Not a lot can be done with the mileage, either. Since the truck's projected use is going to be 90 percent hauling in the mountains, you need to concentrate on improving loaded mileage, which is a bit different from unloaded.

You might look into getting the electric fans that come on the halfton trucks, just make sure to carry the fan shroud, clutch fan and tools necessary to go back to the clutch fan on the side of the road if necessary. If you can make a fully loaded mountaintop climb at 4PM in August without boiling over, then it won't be necessary to carry the clutch fan anymore.

Long tube headers will also help some. Don't bother with shorties, they run about 400 bucks and add 10HP on top of the RPM curve. The factory manifolds are pretty much shorty headers anyway, the gain isn't worth the money.

Best thing to do would be to add a Whipple supercharger to the engine. A Whipple produces a lot of low RPM torque, as opposed to a centrifugal which adds on top end power. This should improve mileage on long trips fully loaded, since the engine will have more power available to it. Along with this, call Comp Cams for a camshaft recommendation, they can get you a towing cam that will also help mileage.

Really, for the cost of doing all this to make the 6.0 perform with decent mileage, you could trade into a Duramax turbodiesel, do nothing to it and have effortless mountain towing, a 2-3MPG drop when loaded instead of an 8-12MPG drop, and an engine that is just breaking in at 100K miles instead of just starting to break down. Not to mention better mileage than a gasoline truck when unloaded.

On the 6.0? Not a whole lot of improvement to be had, especially with a heavy load on.

Why not sell it, and just rent a large PU when you actually need it?? Get the diesel in the summer, and if the winters are SOOO bad that even a block heater and anti-gel won't work, then rent a gasser?? Heck...if you are only out for a few weeks a year...you can get one of the large diesel RV's...on the bus chassis, they get at least 6mpg and you can load all of your stuff inside, and save money on hotels! :-)

Even at $600/wk during the times you rent, you will be BIIIIG $$ ahead over paying for the truck, insurance, depreciation and maintenance. Then just use the savings to really have fun at the shows! Just seems like the "juice isn't worth the squeeze" on this one...

That's a good fit for my suggestions, then. They wouldn't have worked if the only time you used it would be to tow a 10,000 lb trailer, but should work just fine for a light but large load and small trailer like that. You might want to check what drive ratio it has in it. What it boils down to is that if its revving higher than it needs to on the highway, the engine could give better efficiency with a lower gear ratio. Taller tires are a cheap/easy way to lower the effective gear ratio if that would help. The cost isn't cheap though, and so whether it has a good payback or not is going to depend on how much you can get selling the original tires. You won't be able to go with LRR tires because you need Load Range tires similar to what come with it. I'd look at getting the same thing or similar to what GM put on it, except taller and thinner if it was me. I'd expect my hot air intake would work, too, if fitted with a door to give it cold air when more power is needed.

If you don't have some sort of trip computer built-in, get a scangauge. How you drive is one of the biggest determining factors as to whether you get optimum mpg from whatever you have, and adjusting how you drive is free. I can get 2 mpg better than cruise control driving manually at a steady speed out on the highway. The scangauge gives you continuous feedback as to how hard on the pedal you are and what the mpgs are at, so it makes it easy to get the best out of it.

That's an even better idea, sell the truck for an efficient car, and sell the trailer too. Personally I never really saw the attraction to owning a travel trailer, it's just something you have to store, maintain, and pay for, for very little return. My own preference for travel is to get an efficiency apartment wherever I'm going, or a luxury hotel room if I can't get the apartment. In many places an efficiency apartment goes for the same as a modest hotel room. Then you don't even have to pay the fuel for a rented travel trailer. But, if you must have an RV, renting one and letting the rental company pay for the upkeep is better than owning your own and paying all that crap yourself. Yes, the downside is you are sharing a bed with a lot of other people, but cheap plastic fitted sheets on the mattress and your own sheets on the bed with a thin quilt between the plastic and sheet works just great.

They ALREADY own it. They are using it to carry a large qty of artwork to shows, I'd bet.

Based on the age of the vehicle they replaced, they keep things a long time. Selling the truck and top, then renting an RV, and loading/unloading it a bunch of times each year for 15 yrs would be a lot of work and more expensive.

They would have to figure out how much it costs either way. If it turns out that owning is cheaper than renting, then I stand by my suggestion either trading for a Duramax, or modifying the 6.0 with a Whipple, cam and headers. He could probably get a decent deal if he sold his current truck outright, then picked up an off-lease Duramax.

Renting v. Owning
 

Ymmv. :d

Thanks to all....
 

Thanks for the advice, concerns, comments, etc. I really appreciate everyone taking the time to reply!

Regards, Valerie

The main reason I see that diesel is not an option is that they are expensive! Diesel trucks have come a long way since the 80s. I own a 95 Ford Powerstroke that gets 19MPG empty on long drives at 75 miles per hour with the cruise on (my goal is to get it to 24). When I have to drive it 7 miles in to town to meet my carpool it typically gets about 16MPG (it holds 14 quarts of oil that don’t have time to warm up). My friend gets 12 MPG with a 97 Powerstroke Ford that he pulls a 20ft gooseneck camper and a full size car trailer with 2200 pounds of ATVs not to mention the kids and the dogs.
High altitude and cold weather are not a problem, Dodge, Ford and Chevy all have turbos and intercoolers to build enormous low-end torque that compensate for high altitude. In cold climates you are buying winter-diesel has the additives to prevent jelling; this is what the big rigs and tractors run. In addition fuel additives can be purchased when going from a warm climate to a cool climate.

I understand that you have already own a truck and probably don’t want to spent the extra $8000,00 to upgrade to a diesel. As someone who is interested in Power and economy I suggest you start with upgrading the engine, transmission and gearboxes to Amsoil followed by and aftermarket exhaust. Remember in the 70s and 80s everyone added dual exhaust to their trucks? In most cases they gained power and economy. In your truck the exhaust is better from the factory than they were in the past; however, they still aren’t the best. Another mod is to purchase a programmer to reprogram your trucks computer. To purchase Amsoil you will have to go to their web-sight; I suggest you call Summit Racing or Jegs to see what they have available for programmers and exhaust. Understand that programmers and exhaust systems are expensive and it will take you many years to recoup your investment if you drive less than 10,000 a year.
Finally this Ford Powerstroke is my first diesel. I have been driving gas trucks, on the farm, since I was 12 and will never buy a gas truck again!

https://www.summitracing.com/

https://www.jegs.com/webapp/wcs/store...10001_10002_-1

https://www.dieselpowermag.com/featur...sel/index.html

https://www.amsoil.com/storefront/tso.aspx