Fuel Mileage
TECH Resident
Joined: Feb 2014
Posts: 954
Likes: 9
From: Encinitas CA
I've only got 1250 miles on mine since the swap. Hoping for improvement here.
I'd be shocked to see more than 24 on the freeway, though. I guess we shall see. Shocked to hear of some getting high twenties, though that is great.
Doug
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
1985 el camino Lq4 6.0l 4l60e 3.73 gear with 26 inch tires. I get 15 to 16 city and 17 to 20 on the highway running 2000 to 3000 rpm. I spin 2000 at 55 and 2500 at 70. My driving style probably has something to do with it. I know someone who had a 78 buick Electra 5.3l th400 27 inch tires with a 3.08 gear and was getting 26 on the highway. Far tires and a 4l80e brought it down to 20mpg
1989 S10 Blazer, roughly 3100 lbs, 2005 LQ4, LS1 intake, Comp Cams XFI RPM cam 224,228 duratrion @ .050 with .534, .537 lift, shift point set at 6300 rpm, 2004 4L80 with stock converter (1800 lock), 4:10 gears and 25" tall tires. Average 15-19 mpg city and highway (I have a heavy foot), spins around 2500 at 60 mph and 3200 at 80 mph
1989 Trans am GTA 6.0/4l60e. small comp cam(530 lift), 3600 yank stall, 3.73 and 245-55-16 that has not been dyno tuned. I average 20 mpgs driving two lanes to work, 24mpgs on the interstate. it doesn't matter if I run 65 or 80 on the interstate, at 80 mph my cars is running 2800 rpm. These engines like to breathe.
Ah well - I'm a lot more interested in GPM (grins per mile)
than MPGs anyway... 
TECH Resident
Joined: Oct 2004
Posts: 800
Likes: 1
From: Simi VAlley,CA
I averaged 26 mpg on my Route 66 tour a couple years ago but I took the 3.70 gears out for that trip and installed 3.25 gears. The interesting thing is that after putting the 3.70 gears back in the car only lost maybe 1 mpg. The car is just "happy" with the 3.70 gears. I will see how my Victor Jr upgrade effects economy as soon as I complete it.
bone stock gen 3 5.3/4l60e in a '66 c10 with a 3"/4" drop and 3.73 gears on 255/60 17's
gets about 14 in town and 21 on the freeway at 60mph turning ~1700rpm. That's if I'm chill on the loud pedal.
I played a bunch with the dfco to get those numbers. These trucks are just not very aero at all. I might mess around with OLSD next long trip I take and see if I can lean it out.
gets about 14 in town and 21 on the freeway at 60mph turning ~1700rpm. That's if I'm chill on the loud pedal.
I played a bunch with the dfco to get those numbers. These trucks are just not very aero at all. I might mess around with OLSD next long trip I take and see if I can lean it out.
