I started logging my MPG's using a custom PID from a user on the EFILive site, some interesting observations so far. When they tell you that it makes a big difference what speed you drive, they aren't lying! I don't know 100% how accurate the actual numbers are, but the differences between the numbers should be pretty absolute. On all of these maps I hid cell counts less than 25, so these should be fairly accurate.

Take a look at these two pics. Plots avg MPG against TPS and VSS. If you look at the pics with the cell counts, you can see that while cruising (not accelerating or decelerating) it looks like I am in the 15% TPS range at 50mph, 20% at 60mph, 20% at 70mph (keep in mind it steps in 5% increments, so there is no differentiation between 15 and 19%, 20 and 24%, etc), 25% at 80mph, 30% at 90mph, and 35% at 95mph.



Now take a look at the actual MPG numbers. If you look at the above map to get your crusing TPS values, you can see that I was getting 21.4 mpg at 50mph, 18.1 at 60mph, 18.5 at 70mph (this doesn't seem right, but I think the real TPS at 70mph is right between 20 and 25%, which would put MPG somewhere around 16.8, which seems more realistic), 16 at 80mph, 13.6 at 90mph, and 11.6 at 95mph. I have heard before that wind resistance increases exponentially as you go faster, and this seems to support that fact.

 

Here are some other maps as well, I think the above is most informative but these are kinda cool to see too.

MPG plotted against VSS and airflow (g/cyl)

Cell counts:


Values:



MPG plotted against RPM and airflow

Cell counts:


Values:

 

Compounding the wind resistance issue is engine RPM. The LS1-derived motors are at their optimum efficiency at 1800 RPM or so. The higher you go above that, the less efficient the engine is, and the poorer the mileage you get.

 

Why are you driving so fast?

 

Tell that to my truck and my cam The Z06 cam makes good power up top, but poor low-end torque, combine that with a small motor and a big heavy *** truck and its even worse. It needs about 22-2500 rpm to pull its self down the road descent. I just need more cubes, lol

 

 

When I mentioned efficiency, I meant gas mileage efficiency, which will be at a different place on the powerband than torque efficiency.

 

mine gets 20-21 at 80- 85 but only 19 at 70-75. i know this because i went on a trip to arkansas. and everytime i drove i drove at 70-75 and the wife drove at 80-85 with blips up to 90 here and there lol.