Quote:
Originally Posted by slowmover
I think as you confine testing to a particular stretch of road, and that your notes include conditions present, that your test record over a years time will show an average that can be maintained without always running slowly.
So, to take your mind off aero for a moment:
Another suggestion is an airspeed indicator: Yes, it's nice to have a tailwind to get a one-tank (meaningless) high mpg. But it's the average that counts (and experience in operating under defined -- and differing -- conditions). If the average winds up being 14.75 mpg on an annual basis, then an airspeed indicator allows you (with Scangauge) to, say, speed up a little on the favorable portions of road, and then drop back on the return trip; the goal being to maintain the average rather than a one-tank record.
The airspeed indicator will tell you a great deal about winds on a two-laner with opposing traffic. Finding the correct travel speed is what I am trying to say is not always obvious. The old MOBIL ECONOMY RUN teams would haul ass under favorable conditions . . but it took plenty of work and understanding to know how & when!
Warmups can be minimized with block/pan heaters, etc. If the initial fill is 30+ miles down the road, and the next is prior to entering metro traffic (preferably more than 100 miles), I think you've "captured" the high mpg point.
As opposed to a car, handling a truck ideally means much longer distances for acceleration, braking, etc. And a huge emphasis on mirrors (which is why I'd never go down in size, but maybe in shape). Thus any untoward motions from pure lane-centered-ness carry a heavy penalty at the end of the run as all actions cannot be recalled (so to speak), unlike a car where the penalty is meaningless (almost).
The RV.net crowd probably has an opinion on which of these is best:
Safe T Plus
Steer Safe
The Kevin Rutherford/Bruce Mallinson Class 8 Glider Kit tractor has rack & pinion steering.
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So, slowmover, let me ask you some questions, and thanks for the input by the way. You’ve got time in the saddle with big diesels, mine is small by comparison but some things are similar. I like the idea of the airspeed indicator. I’m assuming what that would do would be something like this; if you’re driving 60 mph indicated on the speedo and the air speed indicator says 45, you’ve got a 15 mph tailwind, correct?
Assuming that to be right, at that point I would also assume that would indicate it’s time to take advantage of the reduced drag and speed up a little. That brings up a question. My 7.3L Ford turbo diesel supposedly gets its best fuel economy at 1800 rpms. On my rig with a 4.10 rear end and an E4OD trans, that equates to about 54 mph. Call me Sammy Hagar but I can’t drive 55 for long, I get too impatient, but that’s beside the point. The question is, how much do you speed up without having the increased rpm level cancel out your advantage of the tail wind, any idea?
What I really need is a GearVendor or other gear splitter on the back of the trans so I can bring the speed up to 60 or 65 and the rpms down a little, or a lot. I would replace the 4.10 with a 3.83 but I’m not sure how much that would effect my hill climbing.