In theory you should get slightly better mpg from a premium fuel tune, because the advanced timing allows for increased efficiency. In reality, a lot of driving is done at the lower load levels, where you can run MBT timing regardless of octane in the tank. Both reg and premium should contain the same energy content, from what I can tell here, all the gas has up to 10% ethanol added regardless of octane.

 

With my Edge canned tunes, I got about 11% better mileage with the level 3 compared to the level 2 tune, plus it fit my needs better. I now have the custom tunes and have not run the 93 Perf tune enough to get a comparison with the 87 Perf tune. When I am already paying so much for a tank of gas, it's hard for me to pay an extra 30 to 40 cents a gallon, even if the math says I break even!

 

Very well said. One question - what is "MTB" timing?

I'm thinking the amount of low end/slow driving where advanced timing is not needed is the missing variable in my cypherin. I get stuck in a lot of traffic, even on the highway (oye, NJ), and so the 93 may not be affording me the mechanical advantage.

Anyhow, can you please explain MTB timing?

Thanks for your input.

 

I drive 4 miles to work at a average speed of 35mph and am running 93 setting on my canned Micro Max Superchips tuner and have seen a 2mpg increase since the summer blend fuel came out in April. Running '03 4x4 Screw with a 5.4 and 16mpg over the 14mpg that I had using 87 grade before tuner.

 

how about this?in city driving-part throttle tq is important-i know with my 93 perf tune over my 87 perf tune-part thottle tq is much better-and fuel economy is a touch better-i know on my old streetbikes-advancing the timing was good for lowend and midrange gains- but killed top end performance-...

 

I've been thinking about switching to VMP tunes myself and I'm on the fence on whether I want 93 perf tunes or 87 perf. Justin told me he typically sees anywhere from 5-10hp from a 87 perf to a 93 depending on conditions. So is 5hp worth it when it's near $.40 more a gallon and I fill up more than once a week?

From what Justin just said I'd most likely see little to no gain on mpg the way I drive. Still, I like the idea of having every ounce of power and possible mpg. Tough call if prices keep going up I may go back to 87.

 

MBT timing is the most amount of timing you can run and still make power, regardless of octane. At higher loads you need more octane to continue running MBT timing, but at lower loads you can run it all the time regardless of octane.

 

I guess what I am seeing is that the higher octane tune does not necessarily give you better mpgs. at lower speed/load, you don't need or use excess advanced timing, so the octane does not matter as much as when you push the vehicle and the timing can advance due to the octane being higher.

I do notice that at slower speeds, going from 1-2-3 the truck has more power and I am assuming that the timing is advanced during the low end accelleration. On the highway, when I need to pass, it goes from 4-3 and I can feel the power. When cruising though, at highway or local road speeds, i guess I am not using the advanced timing, so the high octane doesn't matter.

So, in your opinion, is there any real advantage, mpg-wise to using higher octane tunes?

The power is nice, but a lower octane tune isn't bad either and it is certainly cheeper.

What would be the tradeoff with an "economy" tune (which I do not have for the Xcal ii) in terms of economy vs. power. Usually they are on opposite ends of a sliding scale and you can't get both. Can you get economy when cruising and power when you need it?

Can I have my cake and eat it too?

 

Yes you can. Part throttle and WOT are two different parts of the tune, so you can still get economy while cruising and power when you completely floor it.

 

87 = burns faster
93 = burns slower

higher compression = more heat = more chance of fuel igniting before ignition from plug = need for 93

Octane levels don't provide an engine with more HP or MPG's...it's the engineering that determines whether that fuel is needed. If you are supposed to run 87 and you run 93 - you are wasting your money.

 

A good article for you guys to check out:

http://www.idavette.net/hib/fuel/

 

That is why everyone here is recommending 93 octane with a 93 octane performance tune.

 

Is the added expense of 93 worth it to you, not to mention the cost of the tuning?

If 93 costs $0.50 more than 87 @ 25 gallons = $12.50

MPG with 87 = 20mpg @ $4.00 per gallon = $0.20 per mile
MPG with 93 = 20mpg @ $4.50 per gallon = $0.225 per mile

MPG with 93 = 22.5mpg @ $4.50 per gallon = $0.20 per mile

I hope my math is right, but basically you can see that in order to overcome the cost of 93 IF it is only $0.50 more than 87, you have to see a 2.25mpg gain IF your mpg is 20 right now on 87...

Then there's the cost of tuning too.

 

A tune is $50. 93 octane only costs $.20 more than 87 octane. I've done the numbers and it comes out nearly even depending on driving styles. I've done it for both my Mustang and my 2006 F150. When you factor in how much better 93 octane is for your vehicle, it's a no brainer.

 

How do you figure 93 is "better" for a vehicle?

Keep in mind, I'm not trying to be argumentative here...I just don't know how you think 93 is "better?"