MPG fooler - Design phase

[bcbigfoot]

Originally Posted by ISX You don't want a colder temp, you want hotter. But you can only go to 200F, over that I think it throws a code. Ideally you want a 5K POT, as you will be able to dial in the temp easily. 10K is ok, 20k would be tough. Mike is using a 50K and can barely hit the temp he wants because the temp he is shooting for is in the 2K range which is very hard to hit on something with a 50K range, but something with a 5K range would make the 2K window much bigger and easier to hit. I don't know what the ohm for 200F would be, but I am thinking 1.5K.

I want the truck to have the ability to start and run run in cold weather, so I need the IAT to see approx ambient temps. and I can't do that with even a 10k pot as I said earlier lowest temp the 10k pot can produce is only 77f , I suspect with a 5k pot the grid heaters may not even come on in cold weather. For testing I think I will start at 120f and then work my up. good to know that it may throw a code if I go to high. --- Update to the previous post...

Originally Posted by SASQCH I should have my fooler setup in a couple of weeks. Thanks to Mike I ordered a 12" IAT extension cable from Casper electronics. http://www.casperselectronics.com/st...oducts_id=1503. Then I went to the local electronics store and found a double pole double throw miniature toggle, a 5K ohm potentiometer with knob., and a length of 3/c 18 AWG (0.824 MM2) type SVO cable. I am going to cut the + wire in the extension and connect it to one of the wires in the cable (white) and the other side of the cut wire in the extension to the second wire in the cable (green). Then connect the third wire in the cable (black) to the negative wire in the extension without cutting it. On the other end of the cable inside of the cab I will connect wire one (white) and three (black) to each of the two pols on one throw of the toggle (so I can use the IAT like normal). then on the toggle I will connect the + wire pole (white) of the normal throw to the first poll on the second (IAT fooler) throw (so one poll on each throw is connected to the + (white) wire). Then from the other poll of the second throw (green) I will connect to the potentiometer. The other connector of the pot will get connected to the third wire in the cable (black) that connects to the negative wire in the extension. With this setup I will have a T connector to connect to the IAT and the factory harness, A toggle in the cab to go between the IAT fooler and the normal IAT operation, and an adjustable potentiometer to set the IAT reading in fooler mode using my SG II IAT reading. I hope this will be a plug and play unit when I am done with it. When the extension comes in and I start to assemble this unit I will take pictures, make a wiring diagram, and keep a log so if anyone else wants to build one they can. Jim

I like your idea about the toggle switch to make the IAT operate like factory mode. My 10k pot or likely ISX's 5k pot would work as well.

[stodg73]

I just did another run with the fooler on. I think I have a 143* resistor on mine and I got 18.92 mpg. I used 14.986 gallons and went 283.5 miles, and these are corrected miles due to larger than stock tires. 90% of this was highway driving at 80 mph. There was very little idle time with this also. Some stop and go in town traffic:banghead:.

[ISX]

I see what your doing. I think you will have a very hard time hitting the proper marks with a 50K pot. I think there is a code for too cold as well. I would just put it on a switch so you can revert back to normal IAT operation. As for the winter front thing, I think that needs more testing. It was like 10F when I got the same 27mpg as I got in summer and that was without a winter front. My truck has more power and is responsive as all get out. You put the winter front on AND set the fooler for 140F, you didn't try it without the winter front with the IAT at 140. I went 45mph for a week or so a month ago when it was freezing out, the EGT's were 300F the majority of the time. I got 25mpg (I think lugging the engine like that (outside the turbos range) made it a little less efficient, plus going so slow) which proves that even with cold EGT's, the engine is fine. I believe EGT is just one factor, internal combustion temps are another. If it were really 300F then the engine would not run since diesel has to be over 400F to combust. According to my calculations, at 0F IAT, the heat of compression with 17.9 CR and 16.3 CR (which both could be wrong as we know these numbers are thrown around) is only a 50F difference, which is 1000F and 950F. The combustion process is adiabatic (however thats spelled) which means it happens too fast for heat to be lost through the combustion walls or anything like that. I think some heat is still lost, but hardly. At 600RPM the piston is hitting TDC 10 times a second. Now think about how long it takes to heat a block of iron up with a torch.

[Mopar1973Man]

I don't suggest using a rheostat (pot) for the fooler unless you have a way to monitor the IAT temps. Because it doesn't take much to go either way... But 100-120*F is a good normal starting temperature and work your way up. I think 140*F is going about the high mark of normal.

[bcbigfoot]

I don't suggest using a rheostat (pot) for the fooler unless you have a way to monitor the IAT temps. Because it doesn't take much to go either way... But 100-120*F is a good normal starting temperature and work your way up. I think 140*F is going about the high mark of normal.

Thanks Mopar, ISX, and Sasqch for the info. I have a Maxitrip auto computer, a Chinese version of the Scan Gauge with a few glitches but not a bad unit for 59$ at Princess Auto (Canadian version of Harbour Frieght). For testing I will use the 10k pot then once a common resistor # is agreed on then likely a resistor and a switch like Sasqch mentioned.

[SASQCH]

I believe EGT is just one factor, internal combustion temps are another. If it were really 300F then the engine would not run since diesel has to be over 400F to combust.

Please don't confuse EGT numbers with combustion temp numbers. My 93 12 valve idles with egts in the 250* range. Remember that as the piston moves down after combustion and the space in the chamber gets larger which has a cooling effect to the high temp high pressure gasses so in a no load condition most of the compression heat and some of the ignition heat is lost through expansion. If it was not cooling as the volume increased the pistons and exhaust valve would melt and the idle EGT temps would be over 1700* if they were the same as combustion temps.

According to my calculations, at 0F IAT, the heat of compression with 17.9 CR and 16.3 CR (which both could be wrong as we know these numbers are thrown around) is only a 50F difference, which is 1000F and 950F. The combustion process is adiabatic (however thats spelled) which means it happens too fast for heat to be lost through the combustion walls or anything like that. I think some heat is still lost, but hardly. At 600RPM the piston is hitting TDC 10 times a second. Now think about how long it takes to heat a block of iron up with a torch.

Just a minor point that came to mind

--- Update to the previous post...

For testing I will use the 10k pot then once a common resistor # is agreed on then likely a resistor and a switch like Sasqch mentioned.

I suspect that as testing continues we will find that the "best" resister value will change with the outside air temps. It may need to be higher with warmer air temps. That's why I am using a pot instead of a resister. If it turns out to be just one value is best, I can set it and forget it.

Jim

[ISX]

Just a minor point that came to mind

--- Update to the previous post...

Jim

I know the difference between EGT and combustion temp, I have a calculator showing exactly what the heat of compression is. The point I am trying to make is that I think the winter front is degrading performance/mpg. Maybe not mpg, but definitely performance. I didn't dyno it or anything, but with it off and me just driving around with frigid temps, I was constantly wondering what was going on. I know the feel of the power it has very well and I was expecting the usual power, so when the butt-meter spiked, I knew something was going on and all I had done was taken the winter front off. I need more solid proof but the colder it gets, the faster it is. It was -10F a while ago and that thing was an absolute animal. I never got that kind of power with the winter front on. Remember that mine is completely static, so the only thing that changed was colder air going into the engine.

Another thing to think about with cold temps, the engine is at 200F or so, I don't think your going to lose any heat to the cylinder walls at operating temp.. You lose a little bit or else the engine wouldn't have the thermostat open, but hardly. I believe it is well within it's range to burn the fuel efficiently. According to my calculator, going from 0F to 100F is means going from 1000-1300 on compression temps, still well above 400F. This would mean the colder temps (1000) would take more time for the fuel to ignite, retarding timing. I think that is why the 24V spends so much time advancing it. As the fuel gets hot, it ignites faster, so timing advances. I think the 24V determines how much to advance it based on IAT. This is why on really cold days, it knocks really bad, but in summer it is not as bad. Now, fooling it brings our mileage back up, but how if it has cold fuel that is being shot in way to late. I think the fuel gets warmed up a lot, up to the same point as it gets to in the summer (since the engine is 200F in both instances) so the fuel goes in at the same temp.

In other words, I think the programmers of the engine screwed up. Now there might be something with emissions for cold temp driving that they did, so they might have not screwed up. I think they did though, if the mileage drops THAT much in winter, you can't tell me it's not a screwup. I also don't see how it screws up so badly as to drop you more MPG than I do pulling a 4k lb enclosed trailer. I think they just thought "oh the fuel is cold, lets advance the timing a lotttt so it has time to ignite, to the point that it is very inefficient". They should have tested more.

[98whitelightnin]

Well I babied this truck and my UG read 17.5 average mpg and I fill up to see 14.:banghead: Granted, I didnt get the tank to the tip top on the prior fillup but it was pretty close because my needle pegged to full, it may have been 1 maybe 2 gallons off at the most. So now I am just gonna drive it like usual and with the new tires its gonna suck it up even quicker.

[Mopar1973Man]

Still holding a constant 21-22 MPG every trip to McCall, ID now...

[volkswagon]

Don't say that to us Mike:doh: I'd be so tickled with mileage like that I wouldn't have even thought of an mpg fooler:lol: I've come across a guy about an hour from me that works on these trucks a lot and he says his dad has a 99 that is getting 29-31 mpg. The first chance I get I'm heading to his shop to find out what he does. From my own testing lately I get 2-4 mpg better by driving in Drive instead of Overdrive. Running at 2100 rpm is better than 1400.

[Mopar1973Man]

I've come across a guy about an hour from me that works on these trucks a lot and he says his dad has a 99 that is getting 29-31 mpg.

Hard to believe that high...

(I'd love to dig up a article for ya but my internet is in LIMP MODE... Really slow)

[volkswagon]

That's why I'm heading up there asap, to see what he does:cool:

[98whitelightnin]

I know what he does, he goes by the overhead.

[98whitelightnin]

First tank with the new tires was about 15.4 but I picked up a pack of 2.2k ohm resistors and my intake went to 143.6 and my mileage on the ug also went from 15.? to 19.5. I dont imagine its that high but it would be nice to be between 15 and 19.5.

[ISX]

First tank with the new tires was about 15.4 but I picked up a pack of 2.2k ohm resistors and my intake went to 143.6 and my mileage on the ug also went from 15.? to 19.5. I dont imagine its that high but it would be nice to be between 15 and 19.5.

What is a UG? Get some hand calculated numbers. I bet you are getting 19.5 though. Thats the same resistor I used on stodg's truck and it bumped his way up there too.

[volkswagon]

Glad to hear 98whitelightnin. I'm just waiting for the soldering iron to warm up so I can incorporate a 5k ohm POT into my idle fooler and maybe enjoy those numbers too:thumb1: And, ISX, a UG is an Ultra Gauge. Basically a Scangauge by a different company.

[JOHNFAK]

Haven't read this in a little while .... but Guessing this is going to make little difference to someone running a truck in warm climate like AZ,TX or most places in summer - where IAT's are going to get 10+ pretty quick and stay there ? :shrug:Really only for you snowboyz ? :P

[volkswagon]

Well I went for a drive and about the only difference I could notice was the engine sure was quieter with the IAT dialed in to 140-150:banghead:

[SASQCH]

When I decided to build the IAT fooler, I wanted it to be removable so I didn't have to cut the factory wiring harness. Mike pointed me to Casper electronics who sells a IAT extension. I also wanted to be able to switch between the IAT and the fooler. I also wanted the fooler to be adjustable.To this end I bought the extension, a double poll double throw mini dip switch (on-off-on), a 5K potentiometer, and 10 foot of18ga 3 wire cord. I built the control housing box from ABS plastic sheet I already had in the shop.

[volkswagon]

So have you noticed improved mpg's or am I the odd man out who didn't see any improvement?