randym
02-02-2003, 16:47
A couple of posts to other boards that might be of interest here:
Post 1
Since vehical mileage is always a popular subject for posting, I had a thought that should make mileage claims a bit more useful for those comparing the posted figures to what they are experiencing in their similar vehicals. The primary force in generating this idea is the wide disparity in the numbers posted, especially those for 'in town' mileage numbers. First thoughts would be driving style differances and that is certainly a factor, but that aspect can't really be equated for good comparison (how many times do we here that the husband always gets better results than the lead footed wife, or even visa-versa).
What can be done to make the obtained mileage figures more useful for comparisons, is to make use of the hour meters that are part of the instrumentation on all of the GM trucks since 2000, possibly 1999 I'm not positive on that point.
If you are checking your mileage, the only additional effort needed would be to record the hour meter number reout at fill-up and then record it again at the next fill-up when you calculate your MPG. That done, you would then divide the mileage by the hours driven resulting in the average MPH for that tank of fuel. This figure should give a better representation of how the truck is actually being used, ie an average MPH less than 20mph would indicate much stop and go (bad municipality stop light coordination as is my case or excessive idleing of the engine), a number of say 30mph or more would indicate a much more mileage condusive 'in town' situation.
Hope this makes some sense and is remembered by enough posters to make those mileage posts a little bit more informative and useful.
Thanks Randy
Post 2
Since posting my 'mileage posting thoughts' I thought that it might be appropriate to post an update on the current Westers reprogrammed PCM with a highway mileage test done yesterday using the hour meter drill.
Vehical: 2001 Suburban 2500 8.1, 4WD, 4L80E, 3.73, 180*T-Stat, Cold Air Ducted to Air Box, Westers Reprogramed PCM
Milage effecting conditions: 25mph crosswind
Distance of test: 83.8 total miles 1/2 out 1/2 back to refill at same fuel pump
Start hour meter:956.6 end 957.9 duration 1.3hrs
83.8 miles=
Average speed:64.46 MPH
Majority of test: 70 MPH as held by cruise control
Fuel: 5.264gals.
MPG: 15.919
Disparity in average speed vs. desired speed for test of 70 MPH is due to several circumstances.
1.Exiting of service station and accelerating up on ramp to access interstate
2.Aprox. 4miles of road construction, lower speeds with braking and accelerating to flow with heavy traffic
3.At 1/2 way point; exiting interstate, accessing overpass and re-entering interstate via on-ramp
4.Opposite of 1.
This somewhat surprising as I was actually expecting a higher average speed.
The 15.919 MPG number might not at first seem very impressive but I think if you consider the 25 MPH wind, which is enough to require a good bit of steering correction to maintain a straight line, the number becomes quite good indeed. From my experience with the effects that wind has on mileage figures I believe that I can conservatively project that without any wind the MPG would have been over 17; exceptional for a 500 cubic inch engine in a 3 ton plus vehical putting out substantially greater horsepower and torque than stock.
The Westers programming makes quite a differance in the performance of the 8.1. The defeat of the torque management system makes for a pronounced improvement in acceleration; generous throttle application from a stop, if you are so inclined, results in a launch that is extrodinary for such a heavy vehical. General driving requires a noticably lighter accelerator pressure but overall drivability is in no way compromised. Shifts are smooth and solid, possibly a tiny bit firmer than stock. I have never had any hint of ignition knock with any of the programming and only use 86 octane fuel, Lyndon is not a believer in having to use a higher grade fuel. Cooling system temps are no differant than with the stock PCM. In town fuel mileage is consistantly in the 1MPG range better than with the GM programming. I may have mentioned this previously but mileage gains are accomplished partially by leaning fuel mixtures; GM programs excessively rich in order to create extremely high cat temps which provides for an extra cushion for emissions numbers currently imposed on the manufactures.
I've still got to hook up the Travel Trailer with the current PCM for some testing; this primarily to check the increased holding power of 4th gear while using the cruise control. GM programming vertually procludes use of the cruise control when towing if you wish to run in 4th gear, it drops out almost instantly when the cruise is activated. Lyndon also added some additional power between 2,000 and 3,000 this time for towing so that should be interesting to see the results.
I would say that the most surprising aspect of this experiment is that you can obtain substantial horsepower and torque gains along with increased fuel economy.I'm really pleased with this investment, and I already rate it as the best available. I hope that our continued tweeking will be of great benefit to all those future satisfied owners.
Randy
Post 1
Since vehical mileage is always a popular subject for posting, I had a thought that should make mileage claims a bit more useful for those comparing the posted figures to what they are experiencing in their similar vehicals. The primary force in generating this idea is the wide disparity in the numbers posted, especially those for 'in town' mileage numbers. First thoughts would be driving style differances and that is certainly a factor, but that aspect can't really be equated for good comparison (how many times do we here that the husband always gets better results than the lead footed wife, or even visa-versa).
What can be done to make the obtained mileage figures more useful for comparisons, is to make use of the hour meters that are part of the instrumentation on all of the GM trucks since 2000, possibly 1999 I'm not positive on that point.
If you are checking your mileage, the only additional effort needed would be to record the hour meter number reout at fill-up and then record it again at the next fill-up when you calculate your MPG. That done, you would then divide the mileage by the hours driven resulting in the average MPH for that tank of fuel. This figure should give a better representation of how the truck is actually being used, ie an average MPH less than 20mph would indicate much stop and go (bad municipality stop light coordination as is my case or excessive idleing of the engine), a number of say 30mph or more would indicate a much more mileage condusive 'in town' situation.
Hope this makes some sense and is remembered by enough posters to make those mileage posts a little bit more informative and useful.
Thanks Randy
Post 2
Since posting my 'mileage posting thoughts' I thought that it might be appropriate to post an update on the current Westers reprogrammed PCM with a highway mileage test done yesterday using the hour meter drill.
Vehical: 2001 Suburban 2500 8.1, 4WD, 4L80E, 3.73, 180*T-Stat, Cold Air Ducted to Air Box, Westers Reprogramed PCM
Milage effecting conditions: 25mph crosswind
Distance of test: 83.8 total miles 1/2 out 1/2 back to refill at same fuel pump
Start hour meter:956.6 end 957.9 duration 1.3hrs
83.8 miles=
Average speed:64.46 MPH
Majority of test: 70 MPH as held by cruise control
Fuel: 5.264gals.
MPG: 15.919
Disparity in average speed vs. desired speed for test of 70 MPH is due to several circumstances.
1.Exiting of service station and accelerating up on ramp to access interstate
2.Aprox. 4miles of road construction, lower speeds with braking and accelerating to flow with heavy traffic
3.At 1/2 way point; exiting interstate, accessing overpass and re-entering interstate via on-ramp
4.Opposite of 1.
This somewhat surprising as I was actually expecting a higher average speed.
The 15.919 MPG number might not at first seem very impressive but I think if you consider the 25 MPH wind, which is enough to require a good bit of steering correction to maintain a straight line, the number becomes quite good indeed. From my experience with the effects that wind has on mileage figures I believe that I can conservatively project that without any wind the MPG would have been over 17; exceptional for a 500 cubic inch engine in a 3 ton plus vehical putting out substantially greater horsepower and torque than stock.
The Westers programming makes quite a differance in the performance of the 8.1. The defeat of the torque management system makes for a pronounced improvement in acceleration; generous throttle application from a stop, if you are so inclined, results in a launch that is extrodinary for such a heavy vehical. General driving requires a noticably lighter accelerator pressure but overall drivability is in no way compromised. Shifts are smooth and solid, possibly a tiny bit firmer than stock. I have never had any hint of ignition knock with any of the programming and only use 86 octane fuel, Lyndon is not a believer in having to use a higher grade fuel. Cooling system temps are no differant than with the stock PCM. In town fuel mileage is consistantly in the 1MPG range better than with the GM programming. I may have mentioned this previously but mileage gains are accomplished partially by leaning fuel mixtures; GM programs excessively rich in order to create extremely high cat temps which provides for an extra cushion for emissions numbers currently imposed on the manufactures.
I've still got to hook up the Travel Trailer with the current PCM for some testing; this primarily to check the increased holding power of 4th gear while using the cruise control. GM programming vertually procludes use of the cruise control when towing if you wish to run in 4th gear, it drops out almost instantly when the cruise is activated. Lyndon also added some additional power between 2,000 and 3,000 this time for towing so that should be interesting to see the results.
I would say that the most surprising aspect of this experiment is that you can obtain substantial horsepower and torque gains along with increased fuel economy.I'm really pleased with this investment, and I already rate it as the best available. I hope that our continued tweeking will be of great benefit to all those future satisfied owners.
Randy