Towing tips for better mpg's???

[Jimmy J]

Hey fellars,

 

Just wanted to see if anyone out there has some tips for increasing mpg's with my rig...(see sig.)

 

I have a 32ft total length TT. It weighs 5640 dry, maybe 7000lbs with all our gear.

 

Obviously use the T/H mode, but what about gears on the road.? Stay in 3rd? Is ok to put her in drive on the flats? Is the tranny designed to tbe able to tow this kind of weight while in D?

 

I know that by keeping the truck in 3rd, it keeps the rpms in the power band, but wouldn't this consume more fuel as opposed to putting the truck in D, while on the flats?

 

How are you towing? How would you do it if you were me? I know...I know, get the DMAX, but it just wasn't in the cards this time around.

 

If towing in 3rd constantly, where should I be on the speedometer? Just wanna gain some more towing knowlege. Any insight would be appreciated.

[Frozen001]

7000lbs is not to bad for you rig. I always town in drive with T/H mode on. GM seems to have figure out how to keep these transmissions going under a load with out too much problems. Keep an eye on the transmission temperature gauge and if the stays reasonable cool, then you should not have any problems. Also if you find that the transmission is "hunting" for the right gear in drive, then you might want to consider dropping it down into 3.

 

As far as increasing MPG... these 6.0l love gas and there is not much you can to to improve the MPG. I will tell you there is a sweet spot, and having the instantaneous mpg read out help to find it. From what I have heard(since I do not have the mpg read out on my regular cab) it seems to be at or around 65mpg... Other than that have a light foot and that is about the best you can do with out getting into mods...

[GetMore]

T/H is more to protect the transmission than for mileage. Your truck is designed to tow in D. You do not need to keep it in third.

 

First thing to do is make sure all the tires are at the proper pressure. I usually go for max on the trailer and the truck's rear tires, and I think the recommended front pressure is 65.

 

The slower you drive the truck the better your mileage will be, since wind resistance is probably the biggest factor.

 

Oh, one other thing to try is higher octane fuel-it might make a difference. Don't try working your way up (87-89-91-92-93), just go straight to 93, or whatever is highest near you. If it makes a difference, then work your way back down until your mileage drops again. If it doesn't make any difference, then just keep running the 87.

 

For what it's worth, the engine is most efficient from a horespower produced per gallon of fuel used standpoint at the torque peak at full throttle. As the amount of load decreases, the lower the rpm, the more efficient, for the most part.

[Jimmy J]

Thanks guys. I have towed the new TT 3 times since we got her a few months ago. Our last outting if my math was correct, I was averaging about 8.1 mpg's while towing the TT. A little over 12 unloaded. So, I guess I'm at about average with mpg's and the 6.0?

 

I've only had the truck for about 3 months now. Haven't tried any higher octanes yet, been using 87. Our area has 87-89-93. Will go for the 93 on our next outting.

[DSengineer]

If your not pinging on 87 I wouldn't bother going up in octane. Your better off with 87 if she is running good. You will never recoop the added expense of premium fuel in mileage savings.

 

As others have stated keep an eye on tire pressure (truck and trailer) and keep it under 65MPH. Thats about all you can hope for.

[Jimmy J]

If your not pinging on 87 I wouldn't bother going up in octane.  Your better off with 87 if she is running good.  You will never recoop the added expense of premium fuel in mileage savings.

 

As others have stated keep an eye on tire pressure (truck and trailer) and keep it under 65MPH.  Thats about all you can hope for.

 

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Alrighty then. Thanks. She runs fine on 87 while towing. I'll try airing up the tires next time to see if that makes a diference.

[Bart2500HD]

My only bit of advice is to slow down. I started towing at around 60mph versus the 65-70 mph that I used to tow at. For safety and for easier fuel consumption. Going at a slower speed allows the truck to stay in OD longer. Also, you are towing a trailer that weighs at least as much, if not more than your truck. I know the truck will pull my trailer faster, but why push it to save 10 or 15 minutes?

[ADDZ71]

I would disagree with the post regarding if there is no pinging it is not worth the added expense of premium fuel. It is definitely worth experimenting on. My 350 gets about 10% better mileage with 93 so I usually buy 93 when it is less than 10% more expensive. In other words I go from about 13 with 87 to about 15 with 93 an improvement of 15%. 93 Fuel costs right now 20 cent/gal more which basedon 87 at 2.80 is 7% more. In other words the while I pay more at the pump I do not have to show up as often.

 

Austin

[Trouttrooper]

I bet you will get better mpg on the flats in 3 instead of overdrive when towing a load.

Easiest way to test is on a flat stretch (if it's long enough) let the truck shift into overdrive. Once it has done that, don't adjust your foot on the gas pedal and manually shift it down to third. You will probably notice a slight gain in mph. The heavier the load the more noticable it will be. Especially if the rpm's when in D are under 2,000.

[DSengineer]

I bet you will get better mpg on the flats in 3 instead of overdrive when towing a load. 

Easiest way to test is on a flat stretch (if it's long enough) let the truck shift into overdrive.  Once it has done that, don't adjust your foot on the gas pedal and manually shift it down to third.  You will probably notice a slight gain in mph.  The heavier the load the more noticable it will be.  Especially if the rpm's when in D are under 2,000.

 

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You will burn more gass turning higher RPM's in 3rd. As long as its holding D without having to kick down to 3rd all the time I would say leave it in D. At 65MPH I turn about 2200-2300RPM's with 4.10's and 265's. That seems to be the sweet spot. Once you get below 2K RPM with the 6.0 it can't hold a gear worth beans If your cruising at 60MPH or below then 3rd may work out better but then again tow haul will keep it in 3rd for you at lower speeds. That is why I always leave it in D with tow/haul on.

[GetMore]

DSengineer, I'm sure you know that the ECU retards the timing when it hears pinging, and that it tries to run as much timing as the maps allow, up to the point that the pinging starts. However, the knock sensors are very sensitive, and the ECU can correct the problem before you can hear it, so that old method doesn't work any more.

I agree that you shouldn't need to run the higher octane, and that using higher octane than needed just wastes money, but sometimes you have to check and see if the engine does need it.

 

I have a friend that was getting more miles per dollar of fuel when he used higher octane, so it definitely made sens for him. BTW, his truck was an '89 Chevy Stepside, 4x4, with a 350 and 5-speed and over 150,000 miles on it at the time. It liked 89 octane at that point, over 87.

 

Now, the best way to check mileage to see if 3rd or OD is better would be to pick up something like a Scangauge II, if you don't have a DIC in the truck. Set cruise on a flat stretch, check your instantaneous mileage, and then shift to the other gear and check mileage.

[Mattt]

I have basically the same truck as you except long bed. Ive also leveled the front end, and Im running 285's[33"]. I tow a 10000 lb tag toy box trailer with mine. I had my computer re-programmed at a local shop that does it, and the improvement was noticable. Im talking re-program[Westers style], not a plug in Hypertech style.

 

In my truck there is a noticable difference when running 87 vs. 91 when towing. I usually only run 91 when towing. I put 87 in for everyday driving. This could have to do with the dual tune in my truck. Whenever I fill it with 91, I drive it hard at first to get it to flip to the higher tune. Conversely, when its had 91 in it for a few tanks, and I switch back to 87, it will ping for a while until it re-adjusts.

 

My unloaded, in town mileage varies between 11 & 13. I saw my towing mileage jump from roughly 6-6.5 up to 7.5-8 mpg after the computer was done. It also stays locked up in OD longer now, and doesnt hunt for gears like it used to. I tow in D unless Im in the hills, then I drop to 3. Its okay according to the manual to tow in D. Best bet is to just pay attention to what your trans is doing when towing in D. Watch your tach, and listen to you motor to gauge what is going on. If you are in OD with the converter locked up, you are fine. Mine will do that on flat ground and downhill. When I hit a hill, it will first unlock the converter[RPMs up a bit], then if necessary downshift to 3. I would tow in D as much as possible.

 

I would pay the most attention to your tranny temp. That is your biggest concern when towing with this truck. Mine runs 200 at all times with the trailer hooked up. It climbs higher towing up hill, then returns to 200. Im working with someone right now on a MUCH better tranny cooler than stock. The stock trans cooler is a joke on the 6.0/4L80E.

 

I dont think there is much else substantive you can do to increase mileage in these motors other than get it re-programmed. It is so anemicly tuned from the factory that you really have to lay into the go pedal with a factory tune. After having it re-programmed, you will notice that you arent on the gas as hard. I notice it on the fwy mostly, there are times when I move my foot to see if Im even pressing on the pedal.

The factory tune is so bad on the HD trucks that its the least powerful version of the 6.0 motor. I think every other vehicle with the 6.0 makes more hp and torque than the HD truck 6.0. I dont understand GM's rationale for doing this in a workhorse of a truck?!?

[Jimmy J]

I have basically the same truck as you except long bed. Ive also leveled the front end, and Im running 285's[33"].  I tow a 10000 lb tag toy box trailer with mine.  I had my computer re-programmed at a local shop that does it, and the improvement was noticable.  Im talking re-program[Westers style], not a plug in Hypertech style. 

 

In my truck there is a noticable difference when running 87 vs. 91 when towing.  I usually only run 91 when towing.  I put 87 in for everyday driving.  This could have to do with the dual tune in my truck.  Whenever I fill it with 91, I drive it hard at first to get it to flip to the higher tune.  Conversely, when its had 91 in it for a few tanks, and I switch back to 87, it will ping for a while until it re-adjusts.

 

My unloaded, in town mileage varies between 11 & 13.  I saw my towing mileage jump from roughly 6-6.5 up to 7.5-8 mpg after the computer was done.  It also stays locked up in OD longer now, and doesnt hunt for gears like it used to.  I tow in D unless Im in the hills, then I drop to 3.  Its okay according to the manual to tow in D.  Best bet is to just pay attention to what your trans is doing when towing in D.  Watch your tach, and listen to you motor to gauge what is going on.  If you are in OD with the converter locked up, you are fine.  Mine will do that on flat ground and downhill.  When I hit a hill, it will first unlock the converter[RPMs up a bit], then if necessary downshift to 3.  I would tow in D as much as possible.

 

I would pay the most attention to your tranny temp.  That is your biggest concern when towing with this truck.  Mine runs 200 at all times with the trailer hooked up.  It climbs higher towing up hill, then returns to 200.  Im working with someone right now on a MUCH better tranny cooler than stock.  The stock trans cooler is a joke on the 6.0/4L80E. 

 

I dont think there is much else substantive you can do to increase mileage in these motors other than get it re-programmed.  It is so anemicly tuned from the factory that you really have to lay into the go pedal with a factory tune.  After having it re-programmed, you will notice that you arent on the gas as hard.  I notice it on the fwy mostly, there are times when I move my foot to see if Im even pressing on the pedal. 

The factory tune is so bad on the HD trucks that its the least powerful version of the 6.0 motor.  I think every other vehicle with the 6.0 makes more hp and torque than the HD truck 6.0.  I dont understand GM's rationale for doing this in a workhorse of a truck?!?

 

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Matt,

 

Just curious who did your tune and what it ran $$$ ?

[Mattt]

I had a local[soCal] guy do the tune for me. He does fleet maintenance on some of my work trucks. He has all of the different mfg. programs to be able to tweak factory computers. Last I talked to him he was working on a Duramax, and pushing somewhere around 900 ft/lbs out of it. I think it ran me $400.

[GetMore]

Mattt, my guess is that GM detuned the 6.0 in the HD trucks for longevity. They might have been figuring that people would be hauling a lot of weight and therefore running close to full throttle for extended period of time.

Most Escallade (sp?) drivers don't load their vehicles much or run full out for long, and even in the Vortec Max trucks (half-ton) they won't be loaded, so they won't work the engine as much.