[asmech66]

Got a 2009 Chevy 3500 4X4 dually crew cab obviously it's a duramax diesel. I want to get better unloaded fuel mileage and better performance when it's pulling my RV 17-18,000 lbs. I also heard that I could put an overdrive transmission on it. Would this help or hurt?

 

[MUDGRIP]

I think you have a o/d trans already... Welcome to the site!!!

 

[asmech66]

I know it has 6 speeds, however I heard of an additional trans backing up the origonal.

 

[asmech66]

essentially giving it 7 gears and lower rpm's on hwy

 

[daddysLBZ]

Welcome to the forum.Don't forget to fill out your signature!:drink

 

[asmech66]

Ok, Let's see if this signature crap worx

 

[GeorgiaDuramax]

Welcome to the DF!

Congrats on the new truck! :drink

 

[asmech66]

Dangit, now I gotta go outside and take pictures. BRB

 

[setexan]

Welcome to the forum!!!

I don't think an after market overdrive will help you but, would probably hurt you. At 65mph my truck runs around 1600 rpms. If you drop it more the truck isn't going to pull very well. My tranny doesn't like cruising under 1500 rpms in the higher gears 5&6.

 

[asmech66]

Ya know whut, U got a point. Well now, gotta rethink stuff. This is what happen, I listened to just about everything everyone told me about fuel mileage. Forgot about the safety of my tow vehicle. Good Azz point. Yer pullin that Cameo all around, what upgrades have you done to it.

 

[asmech66]

Welcome to the forum!!!

I don't think an after market overdrive will help you but, would probably hurt you. At 65mph my truck runs around 1600 rpms. If you drop it more the truck isn't going to pull very well. My tranny doesn't like cruising under 1500 rpms in the higher gears 5&6.

What all did ya do to yours?

 

[deeretracks]

How bad do you want to keep your warranty? If you ditch the cat and dpf you will get better mpg.

 

[setexan]

I have put about 7000 miles pulling the cameo so far in this truck and pulled it about 2,000 miles with my 07 F-350 powerjoke. The powerjoke didn't want to pull the trailer. I'm not sure what kind of mods you are talking about.

 

[asmech66]

How bad do you want to keep your warranty? If you ditch the cat and dpf you will get better mpg.

I read that some of the stuff on the truck is illegal to take off, don't care about the warranty, just don't want to go to the pokey for some illegal crap.

 

[setexan]

All my emissions crap fell off along the trail!!!

My mileage hasn't improved much without all that crap gone, though. Around 1.5mpg overall.

 

[gr8shot]

Any lower rpms than what the 6 speed already runs will just hurt your mileage and will generally not help anything. Higher rpms are better for towing than lower to a certain point. For unloaded driving, the 6 speed is geared pretty well if you're on stock sized tires. Otherwise the best thing you can do for your mileage is a good tuner and exhaust combo that will get rid of the cat and DPF in your exhaust. Then you'll see a good bump in milaege both unloaded and loaded. But it will in most cases void your warranty.

 

[asmech66]

Any lower rpms than what the 6 speed already runs will just hurt your mileage and will generally not help anything. Higher rpms are better for towing than lower to a certain point. For unloaded driving, the 6 speed is geared pretty well if you're on stock sized tires. Otherwise the best thing you can do for your mileage is a good tuner and exhaust combo that will get rid of the cat and DPF in your exhaust. Then you'll see a good bump in milaege both unloaded and loaded. But it will in most cases void your warranty.

Need to look at the law on it, I would love to do it, but I'm already weary of ole johnny law.

 

[setexan]

I haven't gained much mileage if any while towing without cat and dpf. I baby the truck too.

 

[asmech66]

I haven't gained much mileage if any while towing without cat and dpf. I baby the truck too.

Funny thing today,,, I reset the fuel mileage on the DIC, and at 60 mph it read that I was getting 20-22 mpg depending on if I were on flat or going up hill. This can't get that good of unloaded fuel mileage could it?

 

[gr8shot]

It does vary from truck to truck. Most gain from 2-5mpg, some less, a few gain more. Also depends on how big of a tune you run. the 90hp tune on the Quad usually gets the best mileage, the 40 and 70 not as good, but better than stock.

As for the laws, I don't know what they are in your state, county, and/or city, but if you get tested for smog every year then you'll want to swap the stock exhaust back in before inspection or emissions testing. Other than that, you shouldn't have any problems. I've been DPF free myself for about 6 months now and am way happier.