Re: Any 25 MPG ?

Posted by D13 on December 29, 2005 at 07:18:14 from (216.234.120.23):

In Reply to: Any 25 MPG ? posted by David Bruski on December 28, 2005 at 01:24:19:

1990 Chevy 1/2 ton regular cab 4.3 auto cab high smooth topper. 23MPG at 68 mph highway. Often towed 7000# with little problem. 25 was achievable with some sacrifice:
Drive smooth. Fast starts away from stop is the worst gas mileage killer, followed by accelerating at road speeds. People that run 75mph on the highway, on and off the gas, kill me when they complain about gas mileage.
Drive 68mph, air resistance at 70mph is significantly higher (goes up roughly as the square of speed). I found that 58 instead of 65 on my back road commute gave 2mpg and added 5 minutes to my 50 minute drive. Plus, I don't get tickets.
Cruise is OK without a load or hills.
Keep the AC and defroster on AC equipped cars off. The AC runs in Defrost to dry the air.
Electrical acessories take energy ie HP. No radio/DVD/ extra lights.

Some other tips:
Tallest tires that work. NOT the biggest, tall and skinny will lower your 3.08 gears to 3.00 ratio.
Installing a cab high topper picked up 1 1/2 mpg. Avoid the ones that stick up in the back. No topper, remove the tailgate (good for 1/2 mpg. I've had no first hand experience with tonneau covers but heard 1mpg improvement is not uncommon.
Never tow in OD, accept that 15-17mpg is good with the trailer. Most OD trans' bult before 1998 or so will not take the laod in 4th, will rip up the bearings. Think I'm nuts? I went 196,000 miles before the LOW planetary carrier bearings started to whine in my trans. I think I hurt them towing 10,000# (grossly overloaded the trailer and had to keep in in 1st way more than I like. 3rd is the towing gear, less rotating parts). Never had any other trans issues and just did fluid/filter every 50,000.
If you have to stop, let off the gas or drop the cruise way before the stop. My objective is to let off the gas such that I have to touch the brake the first time when the vehicle is doing 30mph. This took me from 23 to 27mph on my minivan. yes it's a little annoying to be rumbling down an off ramp at 45mph but if you are in a hurry gas mileage isn't you priority is it?
Buy the optimal vehicle for the job. The newer vehicles weigh more for safety concerns and ar continually detuned for emission performance. There are two big breaks, fuel injection and overdrive trans. But my two vans, 98 and 04, have the "same" drive train including final drive ratios, and the new one has less power and poorer fuel economy. Simple is the key.
I once made an 82 3/4 ton get 17mpg when my Dad had never gotton over 13. 45mph max, shift as soon as possible. And that was 3.42 and no OD trans.

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• Re: Re: Any 25 MPG ? db 18:30:01 12/29/05 (0)

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