evilunclegrimace
Does not always play well with others
My '98 Suburban with 5.7, 4l60e and 3.73 gears gets 16.8 on the highway at 70 MPH. Around town I average around 12-13 MPG.
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My 99 Tahoe with a cammed 5.0L with headers, rolling on P305/50R20s and a 3.42 gear turned 1,700 rpm at 70 and would get 22 mpg on trips. 20 is not out of the ball park. My Express van got 18-19 over 5 tanks the last long road trip (2,200 miles, TX to Ohio and back) it was on and that was spinning ~2,400 rpm at 75 mph with the 3.73s and 4L85E. I ran 85-90 for a few hours in good weather across Tennessee as well with a similar average mpg that tank. Running ~3 hours above 80 mph knocked about 1/2 MPG off that tank.Uh.. What are using for reference data numbers? Are your tire diameter the same as OE the truck was built with? Gearing the same? 20 just seems a little unrealistic; at what highway speed, hills up and down?
Getting "good" fuel economy is easy...How are you getting these numbers? You have fuel flow transmitter, GPS for accurate speed and distance. A van, a rolling brick, pushing 2500 RPM moving 6000 lbs plus. Getting 20 to 20 plus mpg? Not really believeable. If you can do that good why isn't GM shouting it everywhere.
This. I had a co-worker who had a late '70s Dodge 3/4 ton truck with a 318. He leaned out the carburetor until it misfired and went back two jet sizes. It was a trick he'd learned from a Highway Patrol mechanic. He swore up and down it got 20 mpg and none of us would believe him. Then he sold the truck to another coworker who verified that, yes, it did get 20 mpg.Getting "good" fuel economy is easy...
...if you don't have to meet emissions requirements.
Van got 18-19 on that trip. 0411 in lean cruise made it possible. Gearing and the OD of the 4L60E when it was stock also made it get decent MPG on flat road 17-18 mpg with no head winds, although the overdrive was nearly pointless outside of that.How are you getting these numbers? You have fuel flow transmitter, GPS for accurate speed and distance. A van, a rolling brick, pushing 2500 RPM moving 6000 lbs plus. Getting 20 to 20 plus mpg? Not really believeable. If you can do that good why isn't GM shouting it everywhere.