Mileage drop after SC install...
07-14-2014, 11:09 PM
#21
Pro
Larger injectors != to using more fuel. You CAN use more fuel, but it doesn't mean you are all the time. Obviously, that's why tuning is required after you install larger injectors, so the computer knows to open them LESS since they can flow more.
Same for air. You aren't using more (or at least much more) air idling or cruising down the highway at a constant speed. Of course when you get into it you CAN get a lot more fuel and air to the right places when you want to..
The only real reason for fuel mileage decreasing at all would be for the extra energy required to turn the blower
Same for air. You aren't using more (or at least much more) air idling or cruising down the highway at a constant speed. Of course when you get into it you CAN get a lot more fuel and air to the right places when you want to..
The only real reason for fuel mileage decreasing at all would be for the extra energy required to turn the blower
I would expect a PD supercharger to get a bit worse mileage than centrifugal since, with centrifugal, it really drives like stock at lower rpms.
I think we all get on the boost a little more than we think as it's so much fun.
To the OP, I suspect that you can tweak your tune and improve it. Good luck.
Joe
07-14-2014, 11:10 PM
#22
Melting Slicks
Member Since: Mar 2007
Location: Santa Barbara CA
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I'm definitely no tuner....but I recall reading a tuning article on the reverse engineering used by HPtuners, EFI Live, etc to change factory tuning where in the changes to the injector scaling reverse tweaks some tables we don't have access to that skews the air tables and throws calculated mpg off. I only browsed it so I might be leaving out some finer points.
HP Tuners did recently add a new table that is called "instrument cluster fuel density". I'm pretty sure it's there so you can tweak and fine tune the DIC reading. I haven't messed with it at all, though.
But yeah, scaling a tune screws with a bunch of stuff. That's something I'm glad I don't have to deal with on my '13 build. It's hard limits are high enough for anything I'm going to throw at it.
07-14-2014, 11:23 PM
#23
Burning Brakes
Mine did change as well to lower, can't expect it to stay the same after adding that. As long as you maintain the SC from kicking in, basically low RPM shifting to stop it from engaging, you may see close to normal MPG but what's the fun in that.
Highway cruising speed 80MPH or below, I still average about 26~28.
Highway cruising speed 80MPH or below, I still average about 26~28.