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MPG fooler - Design phase

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Well gang... I've been playing with theories and ideas for long enough now its time to put them into a design and see if it actually works. We all know the 24V's seem to take a good tumble in MPG's as the winter sets in well ISX proved that with the 12V engines with static timing that MPG's don't change. Well if you look at it the only thing that could be tossing this out the window is the IAT sensor on the 24V is changing the VP44 performance. Most know that colder air produces better HP/TQ because colder air is denser and requires more fuel to keep balanced. Well if you reverse this and warm the air (in theory) the VP44 should retune and burn according to the manifold temp. So what I've done tonight is fished through my resistor pile and found 3 I'm going to use for test candidates. Orange - White - Red - Gold = 3.9K Ohm = 116*F IATRed - Violet - Red - Gold = 2.7K ohm = 132*F IATRed - Black - Red - Gold = 2.0K ohm = 148*F IAT So now tomorrow I'm going to pull 3 test runs on the same piece of highway... Seeing if the highier the IAT temp increases the MPG or not... I'll can give you something to think about... Grid heaters are NOT controlled directly by the IAT... :stuned: With the 2.7K Ohm resistor in place before even starting the grid heater still where hitting as normal. So there is more to the grid heater that the IAT temps... ... On the cutting edge again... :evilgrin:

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I see about 13mpg in town with my 24v and so far the best ive gotten out of about 25 gallons is 330 miles!!! which my best guess is about 16mpg thats un-corrected of course since im running 315 tires:doh:

Do the math 330 / 25 = 13.2 If your truck is a 98.5 dually the 315/85 16 tires are the stock size. Not sure what the SRW size should be.

Do the math 330 / 25 = 13.2 If your truck is a 98.5 dually the 315/85 16 tires are the stock size. Not sure what the SRW size should be.

right what i meant by that was the correct mileage since 315/75-16 are what im running and 245/75-16 is the stock size that came on my truck!!!

Do the math 330 / 25 = 13.2 If your truck is a 98.5 dually the 315/85 16 tires are the stock size. Not sure what the SRW size should be.

WTF? :nono: was that a typo?

right what i meant by that was the correct mileage since 315/75-16 are what im running and 245/75-16 is the stock size that came on my truck!!!

Thats more like it, size-wise... 315/85/16 is almost a 37x12.50

WTF? :nono: was that a typo?

Thats more like it, size-wise... 315/85/16 is almost a 37x12.50

Ya, that should have been 215/85R16/E

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Ya, that should have been 215/85R16/E

Are you sure???

235/85 R16 and 265/75 R16 are both 31 inch tires... Just about 1.5" difference... I know the 245/75 R16 was used as well...

Are you sure??? 235/85 R16 and 265/75 R16 are both 31 inch tires... Just about 1.5" difference... I know the 245/75 R16 was used as well...

Yes Mike, I'm sure that the 98.5 DRW (two tires on each end of the rear axle) truck is 215/85/16 from the factory unless the sticker on the door frame and the stamp molded into the tires both are a typo from the factory. I run stock size 215/85/16 in the winter with studs and go to 235/85/16 for summer. Jim

The sticker is the factory recommended size, that don't mean that a larger size won't fit or work well. The speedometer is almost always calibrated to the tire size on the door sticker so if a larger size is put on, there should be a recalibration of the speedometer. As you probably already know the easiest way to check the accuracy of the speedometer calibration to actual is with a GPS. On my truck I have a box from superlift that corrects for tire size and can be micro adjusted for absolute accuracy. It has a toggle for two tire size settings. I have it set for 215 and 235 respectively so when I switch tires (they are all on rims so no mount/dismount required) all I have to do is flip the toggle and the speedometer is re-calibrated.Just as a matter of interest Sam's club tire shop (at least here in Alaska) will not mount any tires of a different size than listed on the factory door sticker.Jim

The sticker is the factory recommended size, that don't mean that a larger size won't fit or work well. The speedometer is almost always calibrated to the tire size on the door sticker so if a larger size is put on, there should be a recalibration of the speedometer. As you probably already know the easiest way to check the accuracy of the speedometer calibration to actual is with a GPS. On my truck I have a box from superlift that corrects for tire size and can be micro adjusted for absolute accuracy. It has a toggle for two tire size settings. I have it set for 215 and 235 respectively so when I switch tires (they are all on rims so no mount/dismount required) all I have to do is flip the toggle and the speedometer is re-calibrated. Just as a matter of interest Sam's club tire shop (at least here in Alaska) will not mount any tires of a different size than listed on the factory door sticker. Jim

What is the install like on that superlift box, and wow ive never heard of a tire shop not wanting to install tires no matter what the dor sticker says??:stuned:

I got 55K mile on the OEM Michilin LTX MS 265/75R16, 01.5 2500 SRW 8800 GVW. Not the greatest traction tire but still got decent tread life left.

What is the install like on that superlift box, and wow ive never heard of a tire shop not wanting to install tires no matter what the dor sticker says??:stuned:

Install was quite simple as I remember it, it splices into the speed signal wires from the transmission and the box mounts in the cab. I got it around 2002 from jc whitney. Ive been quite happy with it. The hardest part (and that isn't hard) is calibrating it to your tires using a GPS and a straight level highway that you can set the truck on cruse control and using a small screw driver adjust the screws until the GPS and speedometer or SG II (if you have one) read the same speed. The tire shop cited liability reasons for not mounting oversize tires, wall mart and Sams got scared by the firestone blowouts a few years back I think. Here is a link to the unit at superlift: http://www.superlift.com/accessories/truspeed.asp Jim

Install was quite simple as I remember it, it splices into the speed signal wires from the transmission and the box mounts in the cab. I got it around 2002 from jc whitney. Ive been quite happy with it. The hardest part (and that isn't hard) is calibrating it to your tires using a GPS and a straight level highway that you can set the truck on cruse control and using a small screw driver adjust the screws until the GPS and speedometer or SG II (if you have one) read the same speed. The tire shop cited liability reasons for not mounting oversize tires, wall mart and Sams got scared by the firestone blowouts a few years back I think. Here is a link to the unit at superlift: http://www.superlift.com/accessories/truspeed.asp Jim

Sweet thank you Jim I will have to look into one of these!:drool:

The local discount chain sales clod argued with me... He'd looked in his book & it said my POS econo box (my previous DD) took 15" tires. I had to show him the OEM wheels were 14". Duhh!! They would only sell you tires listed as available on that vehicle. Come to think of it, they even gave me a hard time about putting Cooper Discoverer M&S Truck tires on my Ranger PU (early 80s, 2.2 natural). Actually they were on sale & I had the closest store call around, I got the 4 tires from 3 different stores! When the Ranger tranny gave up the Ghost, I had them remounted on wifee's Carovan where they wore like iron! (Same exact size, just Truck tire).

I will admit it sucks to drive with the Edge Comp turned on boost is limited to 22 PSI and very doggy getting built up to speed.

No kidding ..... I have my juice off (sold it) and am going to a QUAD. Its very DOG DOG slow and MPG is down 2-3. Will get QUAD sometime his week. Not expecting any difference - but will keep posted. Mike/ISX - assume this IAT fooling really only works for winter though right ? In summer the timing will be advanced as far as possible due to the voltage of the IAT mappings ?? :shrug:

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Ok... Run #2

I change thing on the truck a bit to match ISX as much as possible.

[*]Change my Cooper STT's 265/75 R16 to my Big O AT's 235/85 R16

[*]Removed the winter fronts

[*]Turned ON the Edge Comp 5x5

The same resistor was used again. 2.7K ohm (132*F IAT temps)

Now I ran the trip again to New Meadows, ID the roads are snow covered, current weather is 3*F above, light to no winds, speed ranging between 45-55 MPH with some use of 4WD. When I reached New Meadows I had a few stops to make so during the stops I used the 6 cylinder high idle. When I got to my final stop I shut down for about 2 hours. (Stopped a friends house) Then fired back up and left for home. Pulled in the driveway with 19.5 MPG on the SGII...

I'd say that a winner in my book... :hyper:

PREVIOUS TEST WITHOUT EDGE COMP

Test run done... (You don't want ot hear it...)

Edge Comp turned OFF!

Round trip to New Meadows, ID and back home (40 miles) pulled 12.5 MPG! :sofa:

It had more power without the front too, didn't it. It hit 67F here (pretty sure we broke a record) and I had to step on it and it was back to being a little slower. When it gets under 20F I can just fly, spools like crazy and everything. Time to add another toggle to the high idle box :lol:

I think so... But now I want to play with the value a bit more and see about tuning in a good general value as a start off... .

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