bluemonstr
Active Member
Take my comment as nothing more than this is how it works from MY perspective.
I have tuning experience on engines since the 90's. (Shadetree mechanic) - The more timing you can run (while cruising) the better fuel mileage you can achieve. Period.
Some are noticing that 89 gets better mileage than 87...this is very possible. As the timing on the engine while cruising is increased (therefore more power is attained easier) - - this is my guess why. As far as 89/91 not being different, It's possible the cruising rpms, requested/actual load is negligible between 89/91 timing - meaning the computer cannot get more timing in there already - as there becomes a limit to how much timing you can put in while cruising. Therefore no difference...ALSO - the OTHER variable is usually if you run 91 / 93 it's for a reason...you are like me...you like the ol' leadfoot mod. When you get on it more (especially in a turbo / forced induction engine) the fuel values sink to the bottom of the ocean. The computer commands more fuel into the ratio - BIG time. Your air/fuel ratio goes from a nice 14.6/1 (while cruising) to about 12/1 or 11/1 air to fuel - depending on the platform it could be even richer - I would bet that because these are 'canned' tunes it's richer...I'm out of town right now but I plan to find my a/r values and see if I can log them. I believe torque pro will provide this. It's a big difference and that doesn't even account for the extra fuel going in as your foot sinks lower and lower in the go pedal.
Make no mistake the tuners can tune for fuel mileage but a lot of the time it's restricted because of the cats. They need a certain ratio to work correctly (If I remember this correctly). I used to tune both my mazdaspeed3 and bmw 335 with a 15/1 cruise fuel ratio. But well...I don't cruise too well and I removed the cat(s).
I learned the importance of the timing aspect and how valuable it was for fuel mileage in my EVO9 back in 2006 - 2008 ish. I was getting horrible mileage (around 16mpg average). I was logging and gradually increased my cruising timing and ended up getting 25mpg in an all wheel drive vehicle. It was night and day.
I have tuning experience on engines since the 90's. (Shadetree mechanic) - The more timing you can run (while cruising) the better fuel mileage you can achieve. Period.
Some are noticing that 89 gets better mileage than 87...this is very possible. As the timing on the engine while cruising is increased (therefore more power is attained easier) - - this is my guess why. As far as 89/91 not being different, It's possible the cruising rpms, requested/actual load is negligible between 89/91 timing - meaning the computer cannot get more timing in there already - as there becomes a limit to how much timing you can put in while cruising. Therefore no difference...ALSO - the OTHER variable is usually if you run 91 / 93 it's for a reason...you are like me...you like the ol' leadfoot mod. When you get on it more (especially in a turbo / forced induction engine) the fuel values sink to the bottom of the ocean. The computer commands more fuel into the ratio - BIG time. Your air/fuel ratio goes from a nice 14.6/1 (while cruising) to about 12/1 or 11/1 air to fuel - depending on the platform it could be even richer - I would bet that because these are 'canned' tunes it's richer...I'm out of town right now but I plan to find my a/r values and see if I can log them. I believe torque pro will provide this. It's a big difference and that doesn't even account for the extra fuel going in as your foot sinks lower and lower in the go pedal.
Make no mistake the tuners can tune for fuel mileage but a lot of the time it's restricted because of the cats. They need a certain ratio to work correctly (If I remember this correctly). I used to tune both my mazdaspeed3 and bmw 335 with a 15/1 cruise fuel ratio. But well...I don't cruise too well and I removed the cat(s).
I learned the importance of the timing aspect and how valuable it was for fuel mileage in my EVO9 back in 2006 - 2008 ish. I was getting horrible mileage (around 16mpg average). I was logging and gradually increased my cruising timing and ended up getting 25mpg in an all wheel drive vehicle. It was night and day.
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