I've done some streamlining to the truck lately... smaller mirrors, got rid of the roof rack, messed around with some EFI tuning and getting really good MPG. Top speed of 55 and driving like granny last week I got over 30mpg highway, and last night I got 25 driving at 70 going down the highway. Is this something that is fairly typical with the right tuning and driving on an LB7?

That's really impressive!

I have mine tuned with a MPG tune and if im going 55 i get around 26-28MPG on flat roads, and i have 285 tires on.
I also have 4" exhaust and no cat. and the EGR is turned off.

I've got 315's for tires, 4" exhaust, no cat, and no EGR, and a K&N filter. At 55mph I'm turning about 1400 rpm if even that.

you reading off the dic. EFI can really help with mpg's , but changing fuel tables messes up the dic. Now one thing I have not tried yet and thats running stock fueling and increasing the timing some. That may result in more mpg's Best I have ever done was 23highway at 55-60

I have found the DIC MPG close but not accurate. I get about 22-23 mpg at 70 mph.

I just got a ECM rework :)& I will let you know how that works out. I also have changed to Killerbees air box :):)& will be getting a 4" exhaust this week or next. I hand calculate all the time & I go 420 miles on a tank & put in 20.1 gals. I always drive at 2000 RPM = 67 MPH. Will update next week. Howard

I'm hand calculating. Fill to the cap and then drive, after my trip I fill it back to the cap and calculate off the trip distance from my GPS since the speedo is off anyway. Can't really see how it could be off doing it this way. Same gas station, same pump every time I test. I'm running EFI using a 130hp or so tune with a little extra timing to get this mileage as well.... yes, I know high hp is bad for the tranny, but only if you put your foot to the floor. :)

Well its time to update as promised. As mentioned before, I have Killer bee's air box installed,Had him redo my ECM for gas mileage & have now finished off with installing a 4" cat-back exhaust system with a 5" tip.
Before I did this, I could get a best of 20 MPG on the hwy & 16-18 with mixed driving. Driving from AZ -left Monday at noon & arriving in TX today, here are the facts & figures. Can only hand calculate! No DIC. When I fill up. I always top off the tank.

#1. This is the 1st time that I have NEVER went out of overdrive,PERIOD.
#2. Before, I would go to 2,000 RPM = 67 mph & set the cruise control.
#3. With the new equipment installed, I do the same thing =READS 70 MPH!
#4. As mentioned, 20 was top MPG. My range was as low as 18.3 when I left on the trip. Mixed drivng. Now the test begins. FYI, very little traffic on the road.


#5. (iST) TANK = 228.7 miles divided by 10.003 gals. That comes to 22.87 MPG.
(2nd.) Tank = 350 miles divided by 15 gals. That comes to = 23.3 MPG.
Since I was on I-10 & knew I would be on it for quite a while with no traffic to speak on, I kicked it up to 78 MPH. Speed limit was 80. Just to see if there was a +/- difference in mileage.
(3RD) tANK = 300 Miles divided by 12.504 gals. That comes to 24MPG!! I really don't care to drive that fast, so we are back to 2,000 RPM & C/C.

VERY HAPPY & CAN'T BELIVE the difference this change has made in the way the truck is running. No changes in any gauges, Trans or Temp.
There is NO PROBLEM entering expressway whatsoever!!

THANKS AGAIN, MICHAEL!! Howard

haha i got 13.4mpg driving roughly 450km round trip going into the city to retest for my pipe. Predator set on 65, driving about 110ish. Big head wind.