hey yall, been a couple years since i've been on here, just got a new truck and need some advice.
i now have an '05 chevy 2500HD 4 door 4x4 w/ the 6.0 V8.
all i've done to it is a drop in K&N filter (stock airbox setup). the fuel mileage is pretty bad, if i am lucky i can get 12.8 mpg average out of it, and that's w/ NO trailer behind it.

i want to do something to it to help the fuel mileage and gain some power before i go to the Hot Rod pump gas drags w/ the 'cuda this year. gonna be towing the car trailer through the mountains so some extra power would be nice.

i have a friend that custom tunes these things, he claims he can get me another 1.5 or 2 mpg out of it and some more power...so i'm gonna do that hopefully this weekend.

since we don't have inspections here, i thought of removing the catalytic converters and having the PCM tuned accordingly. i know these are bad for stopping up when they get some miles on em.
is that even worth doing?

i know an aftermarket exhaust system would help, but i am enjoying the quiet stock muffler. makes me feel old that i actually like it being quiet, lol.

i have a 160 degree thermostat for it, should i use it?

any suggestions for better fuel mileage?

thanks yall, CHIP

 

anyone?

 

Get a magnaflow muffler for it, thats what I did on mine, not loud at all, and combined with an intake tune and an underdrive pulley I picked up about 2mpg. 12.8 would be on the very low end of mileage for me, I've pulled 15.9 crusin on the highway, and thats with the 285/75r16 tires. I have a manual tranny though so that might make a difference too

 

Unfortunately there isn't a ton of mileage left in the 2500 6.0's. Removing the converter won't get you much so it probably isn't even worth messing with. I averaged 12 around town and couldn't ever get above 17 on the highway empty.

 

go find an aluminum block 5.7 from a corvette and swap the motor i was getting 13.5 around town and 18 on the highway with mine before i put the 402 in and im still getting 18 on the highway maybe you should just have the motor stroked lol

 

In my 2500HD the best I could get was 16. Heavy truck +4.10s +6.0L =bad gas mileage. As a tow vehicle I wouldn't worry about it, kinda comes with the territory. As a DD i'd get something else

 

It is what it is, unfortunately. If your friend can get you 1.5mpg plus some oomph, please give me his number...I'll help make him rich. From everything I've seen, "economy" tunes certainly help, but depending on the cost of the tune it can take a while to recoup the investment in fuel savings.

 

i'd flip if i could get 16 mpg w/o a trailer behind it! as it sits now it gets about 13 mpg empty, and that's on the highway! it does have 285-75-16 tires, but they're not making THAT much difference i wouldn't think.
it gets 13 mpg empty, it got 12 mpg pulling my car trailer to Rockingham Dragway 2 weeks ago...the loaded mileage doesn't bother me.
hell, my old '00 w/ a cammed 5.3 and 2800 stall still gets 17-18 mpg.

if you fellas are getting 15+ empty, then mine must be hurting somewhere. cats stopping up, i'll throw in a set of spark plugs, etc. it has 126k miles on it so it's time for some maintenance.

swapping motors or building this one aint gonna happen. that's why i'm selling my '00 1500 2wd...i was about to get a 6.0 for it and build a stroker, then i realized, wtf am i doing? i have a fast street car already so i should just get a nice truck to drive and pull the car trailer with. so now my other truck's for sale...i have enough trouble keeping my other toys in top shape. not to mention i'm building another car to run PTRA True Street (stock suspension, 28" tire, power adder class).

vroomvroom...yeah i don't know if his tune will give me what he claims, but i'd like some extra grunt anyway.

BlownHD...the magnaflow you got, was it a stock replacement? or do you have duals now? mine has dual inlets and a single outlet.

thanks for the info fellas, i appreciate it. CHIP

 

You sound like my wife

 

Pretty much a stock replacement, It was a dual 3" in single 3" out. I'd look for the muffler on ebay, I think you can get them from like $120. I had a shop weld it up, and bought the muffler from them, and paid double that. Then they put a tailpipe on to exit in the stock location, but if I did it again I would just dump it after the muffler. It is plenty quiet, but has a little rumble when you start it. Yeah, i'd try sparkplugs too, maybe seafoam the motor first, and check the MAF to see of that has gotten dirty.