GXP fuel mileage ??
My little instant economy thing said above 35 on the highway when i was crusing at about 70mph. I think that isnt very unrealistic. Either way say i was above 30mpg. Thats still twice what i am at now.
And GM does a lot of things that dont make sense. They did go under after all. I have 2 different dyno charts showing the difference between shell and sonoco. With the shell, you gets spikes throughout the entire power band. I made a post about this a few months back.
And GM does a lot of things that dont make sense. They did go under after all. I have 2 different dyno charts showing the difference between shell and sonoco. With the shell, you gets spikes throughout the entire power band. I made a post about this a few months back.
TECH Regular
Joined: Nov 2009
Posts: 446
Likes: 0
From: Farmington Hills, MI
When I swapped manifolds my average mileage went down to 18s until Jesse and I tuned the MAF, now my average is around 22 again (I reset the DIC after every major change, and I do.a lot of highway driving). I'd bet good money you'll get better mileage after the tune. If you do a lot of highway driving, DOD helps a lot though (at least for the way I drive).
Once the ecm learns to the low octane spark tables, you shouldn't get too much knock anymore. But you will lose some power.
Just because it seemed random, what did GM do that doesn't make sense that applies here?
Once the ecm learns to the low octane spark tables, you shouldn't get too much knock anymore. But you will lose some power.
Just because it seemed random, what did GM do that doesn't make sense that applies here?
Staging Lane
Joined: Dec 2009
Posts: 97
Likes: 0
From: NorWes'
My little instant economy thing said above 35 on the highway when i was crusing at about 70mph. I think that isnt very unrealistic. Either way say i was above 30mpg. Thats still twice what i am at now.
And GM does a lot of things that dont make sense. They did go under after all. I have 2 different dyno charts showing the difference between shell and sonoco. With the shell, you gets spikes throughout the entire power band. I made a post about this a few months back.
And GM does a lot of things that dont make sense. They did go under after all. I have 2 different dyno charts showing the difference between shell and sonoco. With the shell, you gets spikes throughout the entire power band. I made a post about this a few months back.
In fact, it tends to show better figures around 80 than it does playing the good-MPG-game.
A former Impala got its best mileage at 80-90 MPH. Maybe it was just the east Tennessee air, but it consistently ran about 33 MPG. BTW, east Tennessee is like driving in Texas, if you're going 80 you're slightly behind traffic flow.
Link to dyno would be appreciated.
I like my car too, and I like FWD. To each his own.
Anyone who thinks 87 octane is "okay" in an LS4 hasn't hooked a scan gauge up to their car while driving. When my car was stock, I would see up to about 4-5 degrees of knock retard while running 91 octane. As a test, I once ran 87 through it, and was seeing 10-12 degrees of KR on moderate hills or with moderate acceleration. Now that I'm tuned, I never see ANY KR with 91, but I won't ever experiment with 87 again, either.
The point is, when you're seeing KR, the motor has detonation, and that's bad for head gaskets and piston rings (over the long term) and also causes carbon build up in the chambers, which in turn, makes it easier for the car to have problems with detonation.
The point is, when you're seeing KR, the motor has detonation, and that's bad for head gaskets and piston rings (over the long term) and also causes carbon build up in the chambers, which in turn, makes it easier for the car to have problems with detonation.
