Gas Mileage and You

With all the posts about getting better gas mileage and what not, I figured I could give some photographic evidence of what mileage can be obtained especially when people ask whether or not a CAI or exhuast will help out their gas consumption as well as how much wheel size plays a part.

Current mods that could help/affect: TRD cat-back with a 13" WickedFlow max can, URD TCAI, AFE throttle body spacer (guilty of liking the sound I guess ), and URD Maf Cal (tuned for TRD CAI but I'm waiting on headers to retune although I'm sure it plays a minor role currently)

I'll be using the egg shell mod. All speeds are kept between 65-70mph with easy acceleration and trying to keep the RPMs nice and low. So far I've found with all the hills I have to go up and down between Escondido and San Diego; I can keep my RPMs at 2,000 without downshifting to make a climb and maintain speed. Also, most of my miles are highway.

For the first recording, I used 87 from Vons (grocery store gas). Currently I just filled up with 89 from Chevron to see if quality as well as grade will yield better results. Finally, I will sell my kidney to buy some 91 as well. So how much can we squeeze with those mods and 285/70/17 Dynapros?

Vons 87 Mileage 313x1.0741=336.1933 divided by 17.542=19.16505mpg


Chevron 89 Mileage ???x1.0741=?????? divided by 18.533=?????

 

For better mileage you need to keep speed below 65 so more like 60-65

 

That is certainly true, but I think it is illegal anywhere in SoCal.

 

Yep minimum speed is 65

 

Well here we have the 89
Chevron 89 Mileage 337.5x1.0741=362.51 divided by 18.533=19.56mpg
Not a huge difference at all and at 8 bucks more to fill a tank; so far not worth it. Just filled up with the premium so we'll see. Made a trip to Phelan from San Diego so I assume some of the high altitude may have had an impact although speeds and rpms were kept at a constant with the test. Speed did drop a few times to 55 on hill climbs.




Premium is next! Chevron 91 Mileage ???x1.0741=?????? divided by 18.680=?????

 

Unless you are going to take your mods off and run your milage tests, we still won't know what effect a catback, CAI or wheels/tires have on milage.

Also, I read a white paper by Gadget a while back on the Taco computer and performance mapping. This paper also talked through how it handles the knock sensors and timing. In it, if I recall correctly, he states that the knock sensors are not even used to adjust timing at 3K rpm and below. Below 3K, the timing is set by a percentage of the highest timing set from above 3K run/runs. Above 3K, the sensors are read and timing is adjusted accordingly.

Given your methodology, you might not get any timing adjustment if you keep your rpms at 3K or under all the time. And with no adjustment, might not show a milage gain from any power increase due to timing/premium.

What is still not clear to me from Gadget's paper though, is how the upper timing (3K+) setting is set and saved. If it's learned over some amount of miles, or if it can be forced by making a couple of high acceleration runs.