Gas mileage - 6.0L and 3.73 vs. 4.11
Charlie Hicks
I currently have a '98 Suburban 1500 w/5.7L and 3.73's. Gas mileage is
mediocre and power for pulling in the mountains is less than adequate. I
know 4.11 gears would do better for pulling - but 90% of my travel is
non-trailer, city/hiway and run 75 MPH on the Interstate here.
My travel trailer is a 27' that weighs over 6,000 loaded. I also have a 16'
tandem enclosed trailer that will gross 7,000.
I am about to get a new Suburban 2500 4WD 6.0L and am debating on the 3.73
vs. 4.11. No questions what I should get for hauling. There is no
substitute for gearing when pulling.
My real question is about the other 90% mileage. What fuel mileage do you
get running 75 MPH with 4.11s (vs. 3.73)? What is the RPM and do the new
Vortec's prefer to run at higher RPMs? I figure the 4.11 is about 10%
higher RPM. Does the 6.0L/4.11 at 75 MPH hit the sweet spot of the power
curve of that Vortec? I would really like some experienced advice about
this. If you have the 6.0L/4.11 combo - would you do it again?
Should I forgo the 10% hauling power with 4.11 and get the 3.73 for fuel
economy and less engine wear (high RPM)?
Does the engine whine a lot more at 75-80 MPH with 4.11s?
And - one more question - what tires do you folks prefer for towing and
light off-road? I live in the country where rural gravel roads and snowy
winters are common.
I sure appreciate your feedback here.
Charlie
jed
6.0l, auto, 3.73, and pulled two sleds with another in the box. Drove
decent, and were getting horrendous mileage, and the tranny was doing some
hunting as well.
Went a bit later, with same truck but 4.10's, and fuel economy was better,
doing the exact same load and driving.
The change in axle ratio makes a diff of about 200 rpm. Not much diff, but
it did perform much better with the slower gears. When you have a smaller
displacement engine making more horsepower, the only way it is going to
happen is to make revs.
I have found that the big factor in fuel economy, is the 4L80E tranny, and
the Autotrac 4x4. The tranny is not the most efficient thing - it seems to
take some power. And the Autotrac never does fully disengage the front
axle, unlike the lever on the floor. Try this - find someone with Autotrac,
jack up the front end, and with the truck in 2WD, try and turn the front
wheels. You will also find a sticker under the hood telling you to not put
the truck on a rear wheel dyno.
The tranny losses, and the front diff turning, have more effect than the
axle ratio. A 2500 with a 5 spd and the manual four wheel drive, I think,
would see about 4 mpg better than the similar loaded truck.
IMHO, get the 4.10. And even if it does take a bit more gas, (again, in our
case it didn't), it is a helluva lot cheaper to pay the gas than it is to
realize the 3.73's don't quite do it, and now you have to change diffs.
jed
"Charlie Hicks" <chi...@ix.netcom.com> wrote in message
news:8q6i3c$9ak$1...@slb3.atl.mindspring.net...
jed
standard All Season ones. Seem to be a better grade of tire for longevity.
Gary Dumer
I have the Silverado 2000 with 6.0 engine with 3.73 gears and combined city
and highway driving average 14 to 15 MPG. I currently am running 235X85X16
10 ply Micheline and pulling power is fair using Tow/Haul. Tow Haul will
increase shift schedule by approximate 200RPM. The 4.10 gears on my 99 ran
from 10 to 14 MPG with same size tires modest improvement in pulling. My
$.02 is to go with the bigger tire and 4.10 gears for all the power you may
need. Remember use Tow/Haul when pulling it will keep you in the power curve
longer.
gary
Marshall Richards
right,
come as: 2500HD to get the 6.0 engine with the HD AT. And, if you get the
6.0
engine, you have to get the 4.10 rear end. So, if you want the 6.0 engine,
you may not have a choice of rear end. Why they changed it this year I
don't
know, but I asked a couple of salemen and they verified this....6.0 and 3.73
combo are not available.
Good luck,
MR
>===== Original Message From "Charlie Hicks" <chi...@ix.netcom.com> =====
jed
They frequently have different ratios available for different models. Would
have to check the specific application to find out.
jed
"Marshall Richards" <mc...@MailAndNews.com> wrote in message
news:39D1...@MailAndNews.com...
Richard Bonnett
and the 6.o liter engine, 3.73 rear and auto trac 4WD..///and
tow/haul mode.
I haul a boat and trailer combo of 7800 pounds and have hauled it on trips to
the ocean
[ 200 miles ] and used it on boat ramps. The power is there when you need it.
The efficiency is open for questions but under normal driving without hauling
my gas runs about 12 mpg. and can be 13.5 if I tried. Most of travel is around
town
and short hops. The travel over the road at posted speeds will give 13 mpg.
I am paying for the extra weight of a heavy duty truck.
In you case, the 1/2 ton truck is not acceptable for your towing/hauling needs.
A 3/4 ton is essential.
I would be concerned about the burbs if you consider them. They do not all have
the
proper tow capacity and care in selection is necessary. I have seen ones with
capacities equal to only the 1/2 ton truck. You may have options to get a
heavy duty
model.