Wanderlodge Gurus - The Member Funded Wanderlodge Forum

Greetings:

There was a recent thread contrasting 6V, 8V, and series 60 engine
performance. In addition, I compared my fuel economy with a
spreadsheet kindly furnished me by the previous owner covering the
two years of his ownership. The difference between us is as much as
2 mpg, which makes me think I need a tutorial on best operation of
the 6V92.

Questions:

The 6V in our BBs is called "330 hp," but at what rpm? What is the
peak torque? (Peak torque and overall transmission ratio define the
GCWR.) Am I excessively overloaded at 39,000 lbs. gross plus the
7,000 lb toad? Is best economy achieved at the peak torque or peak
horsepower engine speed?

When climbing hills, I routinely use the cruise control until the
engine speed falls below 1650 rpm, then manually downshift the
Allison. When I find the gear which allows constant speed at an
engine rpm near 2100, I continue over the grade, feathering the
throttle as needed. Is this proper?

Differences in economy are related to variation in loading as well
as driver skill: The weight ticket I received from the former owner
indicated perhaps a 2000 lb greater load then, but his toad was
probably 3000 lbs lighter than mine. I've also added a Hydralift
motorcycle carrier. Formerly Lucas fuel additive was used but now
Schaeffer. Not sure about his typical road speed, but I stay around
5 mph below the posted limit. (Going slower seems to invite more
foolish driving by others, negating any potential safety gain.)

More bacground: Recently, I've been operating a Duramax pickup
which goes like a sports car: about 350 hp and 600 lb-ft peak. This
engine is fully computerized, with a useful operating range of
approximately 1600 to 3200 rpm. It's very easy to drive, basically
set the cruise at whatever speed you want.

My previous experience with a DD engine was a stationary application
on an offshore oilfield logging unit, where one set the engine rpm
at a constant value (about 1750 rpm.) Otherwise, I drove heavy
oilfield logging trucks, but not over the road. These were "old-
technology" engines without modern computerization, typified by
rather narrow useful rpm range (and LOTS of transmission speeds.)

Bottom line: Am I getting the best economy to be expected with my
setup, or is my technique substandard? Any experienced BB PT pilots
have pointers to share?

Thanks--
M.R.Kane
'85 PT40

Not sure if this helps, but here's a good explanation
of fuel mileage for Cat motors:

https://ohe.cat.com/cda/files/287140/7/LEGT5364.pdf

David B
'02 LXi, Smokey
Va

mrkane1952 wrote:
> Greetings:
>
> There was a recent thread contrasting 6V, 8V, and series 60 engine
> performance. In addition, I compared my fuel economy with a
> spreadsheet kindly furnished me by the previous owner covering the
> two years of his ownership. The difference between us is as much as
> 2 mpg, which makes me think I need a tutorial on best operation of
> the 6V92.
>
>
>
>
>
>
>
>
>

If I'm not mistaken, the max torque is at around 1600 rpm, meaning
that is about where you will get the most pulling eficiency on grades.
Unfortunately, it doesn't work too well for maintaining speed. I
would suggest you keep the revs up to or higher than the 1600 and it
should perform pretty well. Do not lug the engine at any time.

In the years that I have driven both the 6V92 and the 8V92, I found
that the mileage checked at any given time seemed to have little to do
with the speeds I drove, but when you are only getting about 5.5
average, a half mpg change is 10% and significant. I just don't worry
about it. I take it easy when not in a hurry and sometimes drive
pretty hard when I have to be somewhere in a short time. I typically
cruise about 62 to 65mph and in a hurry at 70 to 75 in the west.

I find that when driving slower and encountering grades, it is harder
on the engine than running faster and holding the rpms up. These
engines have to be wound up for good performance and you need momentum
to keep from working them too hard.

I have years of fuel mileage information covering more than 125,000
miles. Been below 5 and above 6 and that's about it.

R.E. Marabito, Dallas, tX 92WB40

--- In WanderlodgeForum@yahoogroups.com, "mrkane1952" <mrkane@...> wrote:
>
> Greetings:
>
> There was a recent thread contrasting 6V, 8V, and series 60 engine
> performance. In addition, I compared my fuel economy with a
> spreadsheet kindly furnished me by the previous owner covering the
> two years of his ownership. The difference between us is as much as
> 2 mpg, which makes me think I need a tutorial on best operation of
> the 6V92.
>
> Questions:
>
> The 6V in our BBs is called "330 hp," but at what rpm? What is the
> peak torque? (Peak torque and overall transmission ratio define the
> GCWR.) Am I excessively overloaded at 39,000 lbs. gross plus the
> 7,000 lb toad? Is best economy achieved at the peak torque or peak
> horsepower engine speed?
>
> When climbing hills, I routinely use the cruise control until the
> engine speed falls below 1650 rpm, then manually downshift the
> Allison. When I find the gear which allows constant speed at an
> engine rpm near 2100, I continue over the grade, feathering the
> throttle as needed. Is this proper?
>
> Differences in economy are related to variation in loading as well
> as driver skill: The weight ticket I received from the former owner
> indicated perhaps a 2000 lb greater load then, but his toad was
> probably 3000 lbs lighter than mine. I've also added a Hydralift
> motorcycle carrier. Formerly Lucas fuel additive was used but now
> Schaeffer. Not sure about his typical road speed, but I stay around
> 5 mph below the posted limit. (Going slower seems to invite more
> foolish driving by others, negating any potential safety gain.)
>
> More bacground: Recently, I've been operating a Duramax pickup
> which goes like a sports car: about 350 hp and 600 lb-ft peak. This
> engine is fully computerized, with a useful operating range of
> approximately 1600 to 3200 rpm. It's very easy to drive, basically
> set the cruise at whatever speed you want.
>
> My previous experience with a DD engine was a stationary application
> on an offshore oilfield logging unit, where one set the engine rpm
> at a constant value (about 1750 rpm.) Otherwise, I drove heavy
> oilfield logging trucks, but not over the road. These were "old-
> technology" engines without modern computerization, typified by
> rather narrow useful rpm range (and LOTS of transmission speeds.)
>
> Bottom line: Am I getting the best economy to be expected with my
> setup, or is my technique substandard? Any experienced BB PT pilots
> have pointers to share?
>
> Thanks--
> M.R.Kane
> '85 PT40
>