Finding the sweet spot for mileage

[Longshot270]

These are some graphs I made from compiling the numbers from about 4 or 5 data logs I've taken over the last few days. All of the PID's I used can be viewed on the gryphon at any time.

By looking at the graphs it looks like my truck get the best mileage when the RPMs are between 1800 and 2200 while the load is below 50%. I also picked to record MPH so I could figure out what cruising speeds are best. I was kinda suprised because I figured that the upper 60s would be the best. Oh well, this truck is just full of suprises.

I recommend that anyone with a program like MS Excel does this because if you know what conditions get you the best mileage then you can take most of the guessing out of saving gas.

[907DAVE]

Dang......my pdf viewer doesn't work well with your graphs.

[Longshot270]

Well it did get messed up converting to MS word. Then converting to a PDF and uploading messes it up more. Here is a screen shot that should work well enough to figure out what the graphs are trying to show.

[Longshot270]

Got around to testing for some real numbers. Unfortunately it is only for fuel economy.
Here is the intake mod I am talking about


Here is a comparison of the mod with the stock setup.
This first graph is RPM vs the MAF sensor reading. Considering that there IS a difference I would not worry about a lean condition resulting from the computer not knowing that there is more air coming in than usual as seen in aftermarket CAIs. The pictures are a visual representation of datalog readings. When, for example, the RPM was AT 2500 rpm and the MAF was reading AT 70 g/s, a dot was placed. With enough similar readings the dots begin to overlap and show trends.



The scale is a bit misleading (and made worse by compression for internet use) but at 2500 rpm there is about 3 extra g/s (grams of air per second...and since air weighs next to nothing that is a difference) and about 10 extra g/s at 5000 rpm.

Since I didn't have a dyno to test the before and after I can't say how much of a power increase the added volume can add.

But that graph says nothing about fuel economy right? Well that leads to the next graph.

This graph is a little backward because the axes are flipped(blame MS excel) but the results are still the same. This compares the MAF sensor reading and fuel economy (IECON).



Anyone looking at this will see that it promises 3 or 4 mpg...well not necissarily. The peak efficiency (Most mpg from a given amount of air) is under the best conditions. Obviously anything below optimal will be below that curve. The peak conditions are usually flat smooth roads with little turning and for shorter sections that are down hill. Sometimes I was barely putting any pressure and that is how the 25 + showed up (or at least that is the only way I can think to explain it). I would consider anything below 23 mpg for this to be reliable because I can get up to 22 mpg on certain roads. 18 mpg is almost always expected for cruising, 19-20 is common for many roads and then there are a few roads where I get 21-22 every time

Edit: I want to mention that the high mileage was with the intake mod installed...there is no way my truck will get 27 mpg in the current state it is in.