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Interesting observations using the "scan gage" in my HDT


mr. cob

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Howdy All,

 

I recently bought and installed a scan gage for my truck, I am still figuring it out but on my last trip to and from my home in western Washington to Moab Utah and back I found some interesting things to discuss.

 

In the past I have held my traveling speeds to 60-62mph as I thought that was were I would get the best fuel mileage, however using the gage and checking the numbers the gage gave by hand calculating gallons burned by miles traveled I have found that I get the same or better mileage while upping the speed.

 

The gage can be set to display four different parameters on its face, I have it set to display, horse power being generated, percent of load on the engine, present fuel mileage in real time, and boost pressure. I have found that when in the mountains I climb hills faster and burn less fuel when running at higher speeds, sounds counter intuitive but the hand calculated numbers seem to prove it out.

 

Running at 60-62mph, in 10th gear the truck would sometimes down shift into 9th, pull more boost and display more percent of load at higher horse power then when taking on the same hill at 70mph and staying in 10th gear. I ran from home to Moab using the gage to keep track of fuel mileage at my usual 60-62mph, on the return trip when safe and the speed limits allowed I ran at 68-70mph my hand calculated fuel mileage at both speeds was within a tenth of a mile per gallon.

 

I am "assuming" that the aerodynamics of the truck really don't come into play until one drives over a minimum of 60mph and that being in the rpm range where the truck is producing more horse power thus less down shifting on steep grades is what makes the difference in how much fuel it takes to cover the same distance at different speeds. At 60-62mph my engine is turning1150-1200 rpm at 68-70mph its turning 1400-1450 rpm. My rear axle ratio is 3.55-1, engine is a Detroit 60 series 12.7L rated at 430-470hp. On a hard pull, pedal to the metal the maximum horse power displayed on the scan gage was 338 at 28 pounds of boost.

 

I would be interested in hearing what others have to say about these numbers and my observations using the scan gage.

 

Dave

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No pyrometer....to see what your EGT's are?

Howdy MrSeas,

 

There is no pyro gage on the dash, and I couldn't find one on the scan gage, I am "assuming" the ecm would stop fueling before the egts got to the danger point. If anyone has any information concerning the ecm and its ability to limit egts I am interested in hearing about it. Thanks.

 

Dave

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Dave,

 

I've seen similar on my truck. On nice flat drives, lower speeds maybe yield a little better mileage, but especially in rolling hills I do same or better at higher speeds. I'm usually running between 65-70, but even at speeds much faster I never saw any real penalty at the pump.

 

As far as EGTs, about the highest my factory gauge has ever shown is about 800F--well below danger zone--and that was climbing out of Laughlin towards Kingman in 110 degree weather.

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Dave

I have a Scan Gauge in my diesel smart and also have found that sometimes the fuel economy is better running one gear lower and keeping the rpm up. Mine is set up with both instant and average fuel economy, that way I try to keep my instant number better than my average number. I think I improve my economy by twenty percent when I pay attention to the gauge. It will pay for itself in no time.

 

Nigel

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I am running the Silverleaf VMSpc on a Acer Netbook in my truck with the D12 and a standard 10 speed manual transmission. One of the first efficiency improvements I noticed was to stay in 8th gear up to 45 mph, 9th gear between 46 and up to 55 and to NOT get into 10th at a lower speed. This smacked right in the face of getting into the higher gears ASAP to get the best mileage. I now run 9th more often than I did before installing the VMSpc and avoid shifting into 10th until I am over 55. As far as getting better MPG running 60-62 on the Interstate I found that was a false assumption. You are better off to forget speed and pay closer attention to engine load. Setting up a histogram with the gauge for engine load gives one a great picture of what is happening over time. This, of course, dovetails with what David has shared about his Showhauler MPG. A good explanation as to why it works this way can be found here.

 

I am still learning and experimenting with the different parameters I can monitor with the flexibility of the VMSpc. My best efficiency related to load, speed, turbo boost, gear and RPM have yet to be finalized. I need more time on the road under varying conditions to analyze the captured data. BTW - I have a Scan Gauge on my GMC dually with a 7.4 gas engine. I love it!

 

 

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I have found the same thing.....sometimes running faster is more efficient. That was on my autoshift ISM 400hp/1450 torque.

 

On my D16 Volvo the computer/trans is so smart that I'm not sure what works best. The durn thing coasts down hills, after all :)

 

BTW, I have a VMsPC for older trucks I'll sell if someone wants it. I'll have to dig it up and confirm what it will work on....but I think pre-2005 Volvo's. I have a new verwion with wifi for this truck...but I have to get around to installing it.....my tablet PC is acting funky which I have to solve first.

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I might be interested in that Jack. Provided it will work on the '98 Cummins M-11 with manual trans.

Do you have the electronic bus in that truck? The M-11 has less electronics than the ISM. Randy might know.....Otherwise I'll have to research it...

 

In any case, I'll not have the opportunity to pursue this until we get the campground open next week. Plus I have to start testing the Max Signal amp and some nifty new WiFiRanger stuff..... not enough hours in the day. Who said they get bored in retirement?? ;)

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Do you have the electronic bus in that truck? The M-11 has less electronics than the ISM. Randy might know.....Otherwise I'll have to research it...

 

In any case, I'll not have the opportunity to pursue this until we get the campground open next week. Plus I have to start testing the Max Signal amp and some nifty new WiFiRanger stuff..... not enough hours in the day. Who said they get bored in retirement?? ;)

We have a grey round plug under the left side of the dash.

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Jim - if you have the gray round plug the VMSpc Jack has should connect fine. If not, I can tell you what pins to tap (there are only two plus 12 VDC). Not sure what JIB Jack has but it most likely it has a nine pin RS232 port for output to the PC. To use a more modern PC with no RS232 you need to purchase a RS232 to USB cable and install the associated drivers. I am using the Sabrent cable and it works great. My netbook runs Windows 10 and the Windows 8 drivers from Sabrent work OK. For engine type I select the Cummins 450 HP rather than the Volvo D12 as the D12 engine software won't compute HP and Torque (derived from load and RPM) - the software isn't set up right for the D12. But, the data stream for the Cummins is identical to the D12 so no sweat. There are scores of different engines to select. The neat thing is VMSpc will run on most any PC - even an old one with Windows 95. I have a little RGB to composite video converter that allows use of a generic 7" video display if you want to hide a PC in a cabinet. I'm not using it but when testing it produced a readable display. Once VMSpc is installed you need to build your gauges - you can select any of them, put them where you want and select a color, size, warning lights and sounds, text, background, etc. Gauges not defined in the OEM software are created by using the PID sniffer feature. I have several gauge screens, one has Microsoft Streets and Trips 2013 in the middle and the gauges on the sides. Lots of possibilities and fun! I'm still learning and designing :)

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Dang, Randy....if you are enjoying the Silverleaf that much, you need to sweeten the trade we made. Seriously, I am glad that it is working out well for you. Soooo, the Cummins engine file will show HP and engine Load and the Volvo engine file won't ?? Have you had any more discussion with Silverleaf tech support or just decided that the Cummins file is satisfactory ? Hope you are all well....give Nancy a hug for me and give Oscar a treat and an ear scratch. Charlie

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Randy, I have thought about this after reading your posts, and looking at the web site, but Im far to technically challenged and dont really have room for a lap top on my dash of our FL-60 Sport Chassis, now maybe something like the size of a tablet might work and some training on how to set up and the functions of the unit, and suggestions ?

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Randy nailed it.....that is the one I have.

 

For display, you can use a Windows tablet, or one of the hybrid computers. It takes up very little space. You don't need a fullblown laptop. On the VMsPC I have you do need to use a physical cable so you need the adaptor Randy described and a USB port on the tablet. Be careful in buying Windows tablets because some do not have a USB port.

 

I won't get to digging this out for at least a week. But once I do I'll post it with an ad and pictures. I'll also look to see if I have a W tablet that I can let go with it.....

 

It is a VERY nifty device for those that want to know what is going on. I doubt it will continue to work with the NEW Volvo's that are encrypting the data bus. But my trucks are not that new.

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