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.
1997 5.7 only 9 mpg
- Thread starter travis mattson
- Start date
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L31MaxExpress
I'm Awesome
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.
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.
Getting "good" fuel economy is easy...
...if you don't have to meet emissions requirements.
Even if it was possible to get those numbers, there is " no one size fits all". Different States. Different trucks. Different driving styles. Different geography. Different wear and or age. Different additional equiptment stuff ie weight on onboard.
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.
The downside is that running lean make oxides of nitrogen, which cause acid rain. If you have enough engines in a region running lean, your clothes start disintegrating when it rains. Paint gets eaten. Ground water gets polluted. Asthma and other breathing problems increase.
I do believe that a lean cruise is a good thing. The overall amount of pollution drops more than the NOx increases, you use less gas, and you save money.
thegawd
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my k1500 Burb with 3.9% larger than oem tires, 373 gears, and over half a million kms gets above 17 MPG all the time. with that size of a tire and the 373 gearing my truck is in the fuel economy half side of the gearing charts. of course those charts only assume a 1:1 ratio and these trucks have overdrive. I never even clued into that overdrive ratio until someone pointed that out on here. I no longer post those gearing/tire size charts because of that. but tire size and gearing has a lot to do with fuel economy.
L31MaxExpress
I'm Awesome
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.
It was a 305 powered Tahoe netting 20+. Tahoe has less frontal area and is lighter. Also the 305 takes a little less power to run itself cruising down the road, especially loafing along at 1,700 rpm. Similar to how the multiple displacement engines work, the 305 was cruising with minimal engine vacuum. From memory it only pulled 6-8 in/hg on level road.
I don't care what mileage I get as long as I get where I'm going in less than 14-1/2 seconds
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