Fellow Suburbanites... how's your mpg doin'?

[minisub]

With the Tahoe (a bit lighter) I got nothing when I did mine in ~'05 and I recorded every tank at the time.

I'm with Aces, I get 16-18 on summer fuel, more like 13-15 on winter fuel with 3.73s. I have had high teens, very low 20s on long, cruise controlled, slowish highway runs when a tailwind was involved. But it certainly isn't typical.

I so wish I didn't have the "tow package" with the 3.73s....

 

[Woody35]

i get 15 mpg pretty much all the time whether im towing or unloaded. this is all city except for short trips to the country. i got a lead foot and hearing the exhaust system doesnt help so it goes down a lot

 

[Dave01]

Barely 14 winter, maybe 16 on a good day summer. I wish I could swap out the 4.10's ........

 

[buddy]

Anyone that wants higher ration can get taller tires. A couple inches taller will drop you down to 3.73 equivalent. So if you need new tires it is something to consider. Would just need to correct the VSSB module.

 

[Dave01]

I have the 265/75-16's on now, if my math is correct that's a 4% difference from stock, should give a ratio of 3.94 give or take a bit. I do need new tires before winter, I'll take a look but not sure I want to go bigger than these. I did not correct the VSSB module but I do the correction when figuring mileage.

I don't tow heavy very often, 6,500 a few times on 30 mile trips and mostly 4,000 lb. boat, so I don't need the gearing. Even with these tires I'd think about going all the way to 3.42's, I do a lot of highway driving and I'd love to have it loafing along at 70 mph rather than the 2,400 or so I see now.

 

[guybb3]

Anyone that wants higher ration can get taller tires. A couple inches taller will drop you down to 3.73 equivalent. So if you need new tires it is something to consider. Would just need to correct the VSSB module.

So what would be a taller size from 235/85-16?

 

[nobby]

Just did a tank full pretty much all highway driving, 65-75mph, some hills and some AC loaded with tools. Tyres are fairly worn so they are more akin to a full tread 245 than a 265. 19.7mpg.

Cheers
Nobby

 

[Steve93mustanglx]

knkreb must have read my mind... been meaning to post a thread like this.

Just started a new job in downtown Richmond. I have done every conceiveable mod and routine maintenance item I could before this job started to get the best possible mileage. See mods below. 3.73s with stock tire size, 4x4. 160k miles on motor.

It's roughly 15 miles 1 way. I got 14.2mpg with a/c on in city driving... both weeks.

Went on a 360 mile trip last weekend up I-64 west from Richmond to Staunton (VA), and south on 81... mostly up hill. 16.9 mpg. 100 miles using a/c, load of Boy Scouts and gear. 65-70mph. No cruise control.

I must say, I am disappointed. I have a noisy new (rebuilt) injector again (fuel knocking off and on) so that has some impact, but how you guys could get 20mpgs seems like fantasy land with my 6.5 experiences.

I have replaced injectors, vac pump delete, new dmax fan and clutch, all fluids new, FTB, watched speed like a hawk, no gear stored on top. Mountains (3800 ft max) are a factor, but there is a down side to each one. Thought it would balance out to 18-19...

 

[buddy]

So what would be a taller size from 235/85-16?

235/85/16 would be about 31.5" tall, about same as 265/75/16s
285/75/16 would be about 32.75" tall, which would drop RPMs but increase surface friction, although I dont think our torque monsters care about a little surface tension at 2000rpm.

If your truck isnt getting good MPG first thing to do would be verify speedo accuracy at highway/interstate speeds. Then look at what temperature its running, as I think they will be most efficient around 200F. So if you are at 185F all the time, youre probably hurting.

 

[Dave01]

When I bought the Sub it had 235/85-16 on it. When I switched to 265/75-16 my mileage dropped about 1 1/2-2 mpg. I'm not sure if it was the weight of the tires or the increased surface area, probably both. I woudn't go back to the skinny tires, like the 265's, just thought I'd comment for those who are looking at changing tire sizes.

Steve93, what are you running for tires?

 

[buddy]

Thanks Dave01, did you by chance change anything else in the timeframe that you switched to the 265 tires? Like got the GLE or TM or started using WVO. Is your mileage using WVO or diesel?

For me, I started with 15" wheels with 225/75 tires and upgraded to 17", so the 235/75 were a big jump in height for me.

 

[Steve93mustanglx]

Steve93, what are you running for tires?

Yokohama Geolanders, 245/75/16

 

[Dave01]

I don't check mileage on veg, too much of a pain in the neck to fill both tanks at the same time, etc. The mileage on the 235's was the first 5,000 or so miles after I bought it, then switched to the bigger tires before the GLE and TM. The one variable is the IP, it was changed at the same time as the tires. I bought it from Heath, a reman, and had it timed, so I woudln't expect the new IP to have caused a mileage drop but I guess we can't rule that out. The only way to know for sure is to go back to the 235's, and I don't plan to do that.

 

[RD400HP]

I have a question for you turbo guys what gets better mileage, turbo or a N/A.

Mark

 

[Rodd]

I was getting 14 mpgs then added a racor prefilter and got 17 then the next 2 tanks I got 10. I just swapped out my racor and noticed a lot of flakes in the looking glass. It appears to be getting better. We'll see.

 

[buddy]

NA diesel usually gets significant better mileage but is slow and weak.

 

[Dave01]

I was getting 14 mpgs then added a racor prefilter and got 17 then the next 2 tanks I got 10. I just swapped out my racor and noticed a lot of flakes in the looking glass. It appears to be getting better. We'll see.

I'm not sure why a prefilter would boost mpg or drop it. If the lift pump can't build pressure through the filter you'll starve the IP and fishbite, if fuel is feeding properly the fact it's filtered better shouldn't change mpg. Not sure I understand why you saw those results.

 

[RD400HP]

NA diesel usually gets significant better mileage but is slow and weak.

Thanks for the reply Buddy.

Mark

 

[knkreb]

NA diesel usually gets significant better mileage but is slow and weak.

I always associated an NA diesel with being a 6.2 only... less fuel, less hp/torque... less fuel to burn, and 0-60 sometimes before AARP membership kicks in. How 'bout the 6.5 NA? Is it same for same on efficiency/mpg?

 

[Acesneights1]

I always associated an NA diesel with being a 6.2 only... less fuel, less hp/torque... less fuel to burn, and 0-60 sometimes before AARP membership kicks in. How 'bout the 6.5 NA? Is it same for same on efficiency/mpg?

I would think so. There is almost no difference. I seriously doubt the tiny bit of displacement would factor much. 6.2's are not that bad. I currently own and drive two. I would not want to tow anything far or heavy with it but otherwise they run great and have alot less problems than the 6.5TD trucks The simplicity of the fuel system accounts for alot of that. Also IMHO the 6.5 wasn't beefed up as much as it could have been for the extra HP/Turbo etc. Alot to be said when you don't have to carry software or a codescanner. 6.2 ain't gonna win no races but it will always get there.