in banish's book, it says that if you really want to improve fuel economy, you want to focus on advancing the timing in the lower loads so you require less throttle to reach speed

 

If you have the right engine management you can lean burn it if the heads is efficient enough. Afr and exhaust gas temp is the problem. General rule of thumb is N/A 13.8 afr = best power. Goverment likes 14.2-14.7 for emissions. If you go leaner than 14.7 it is hard on the exhaust valves because EGT goes up. But if you keep going leaner say 18 to one or so there is not enough fuel and the temps start going back down. With that said. If the heads are efficient enough to run a really lean mix so the EGT is not sky high and the engine not miss you are set. MPG around 40 should not be a problem. But that is a lot of ifs...

 

After a lot of read for our Z usually best power is about 12.8-13 afr.
May be i'm wrong but also tuners make in that way.
Up that 14.7 is quite impossible to obtain and also very dangerous for engine.
Simply Z is not a car for fuel economy (and here is speaking italian man, gasoline is about 2.5$ for liter in my country !)

 

Just curious for those with UpRev,

One of my maps is economy but after driving on the highway to work under that map, I'm still avg ~23mpg

Is that too low for a VQ35HR with just ART Pipes + Shockwave TDX2?

 

there is no set MPG. It depends on humidity, air temp, elevation, tire friction, type of pavement you drive on, wind resistance, how clean the fuel is you are using (quality), and most important the driver.

23mpg per tank average is decent.

 

I improved my MPG's considerably just by adjusting the target maps a little in the lower RPM areas. From the factory they are quite aggressive and will dip below 13 even at light throttle at low rpms. I only run the 'econo' map on long drives and purposely 'stay out of it'. Would not recommend leaning things out unless you already know how to drive for fuel economy. I was able to go from high teens to mid-20's for long drives.

 

Ah.. ok. It has been raining a lot these few days. Perhaps that is why my mpg is so low. 50-70% humidity in TX @ 90+ weather. I thought something was up with my eco map. I figured that since I was avging around 23-24mpg pretune (on highway), after the tune should be more efficient to begin with on the main 93 octane map and eco map should be even better.

 

i also have art pipes and a the tdx2 with a K&N drop in and i gained 2-3 mpg with these additions for highway cruising. i have a vq35hr and run 25 to 26 on the highway at 70!

 

We are getting 34mpg going around 80mph between Albuquerque and Denver (high altitude which really helps).
That is with 6mt, steady foot, no cruize control, no "oh geez that thing want's to pass a z???" and 08 rev-up engine in 03.
Before swap got 32 to33.

 

any mods to the car? injector changes, tire or rim changes, etc?

Is this going by the computer MPG or are you actually calculating it from amount used by mileage driven?

I have found the computer on the z to be wildly inaccurate.

 

Just an idea. Tuning for a better fuel economy through throttle opening table, not letting throttle to open more than 50% or so .

 

cheaper and easier to tune your foot.

 

Well, maybe you are onto something, binder. That was the computer read-out.
No, absolutely no mods.

 

The throttle change maps are the biggest problem like you said dropping down into the rich area on shifts and any changes in throttle. Fuel enrichment map on haltech adjusts this nicely.

Although running mid 20's might work I definitely am not going to run my expensive built block on low fuel which can cause excessive wear on the cylinder block. Now my honda insight shows 25:1 in lean burn but I don't care about it's engine. lol

Ya, people were claiming wild readings after turbo or supercharger. Even a change in tire diameter will throw off the calculator. The only "true" way to get a reading is to calculated it based on fuel used and mileage driven (and make sure the mileage driven is calculated properly for oversized tires/rims). Injector changes make a huge difference in calculated fuel by the computer since the injector pulse width will be far lower for the same output on larger injectors it will think less fuel is being used.

 

The Cobb AP has a mpg mode for the Evo X since it is quite a gas guzzler. Running narrow wheels/tires might help.

 

Their cruise stoich is the same. It reduces boost pressure and throttle opening which limits the drivers from getting hard on it therefore increasing fuel economy.

Driving for fuel economy in normal mode verses econ mode will yield the same results. So basically the tune makes the idiots drive more "economic" so they don't waste gas.