Surprising increase in truck MPG

Do you really think this is a reliable way to establish mileage? Is this something new? Has this ever been proven? What would happen, say, if one would do this over ten tankfuls? Do you think this would give an accurate measurement over a long trip? Do you think anyone under 25 could do the math?

WHAT AN OUTSTANDING NOVEL IDEA!

Steve

It is a Silverado 2500HD pickup with a 5.9 liter engine, not sure about axle ratio.

In 1973, I owned a 1962 Ford Falcon car, six cylinder engine, manual shift transmission.I was driving in Kentucky one night and the engine suddenly stopped running.I checked under the hood, the air filter was so clogged it had stopped the air flow to the carburetor.I dont remember what sort of miles per gallon I was getting with that car before it stopped running, but it must have been considerbaly better after I removed the clogged air filter.Of course I bought a new air filter later on. cuhulin

I have receipts for gas somewhere, I can find them. The number of gallons added was more or less consistent every time.

i

I didn't say anything about reasonable - but now that you introduced the concept into the conversation - only a moron would call 10 mpg "perfectly reasonable".

The price of fuel is controlled by one thing - availability. The more fuel that is available the cheaper it is. The price goes up when there isn't enough oil on the market to meet demand. Buyers bid up the price until someone drops out of the bidding and then the price reaches an equilibrium with demand. Prices are headed up because there is no way today to increase oil production as fast as demand is increasing. The guy getting 10 mpg is going to probably start finally conserving when it gets to $10/gallon or is he so stupid he will still be driving this truck (and driving up the price of fuel) when gas costs $30/gallon?

If millions of idiots like you had not been wasting fuel over the last 60 years then that wasted fuel would still be in the ground If it was still in the ground it would be easily available and thus it would be cheap. Petroleum would still be only a few dollars/barrel if it was still as available as it was 50 years ago. And it would still be easily available if it hadn't been wasted. It's easy to see why someone 50 years ago would not be smart enough to understand that, but what excuse does someone looking back have?

-jim

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I find that hard to believe, but I suppose it might be possible with closed-loop engine controls, a high-compression engine, and a knock sensor/spark retard *if* you were previously running on low-octane Mexican fuel. Not all vehicles have closed loop, however (basically any engine without an oxygen sensor has no means of feedback mixture control) and I just don't see any mechanism by which a less energy dense could actually produce a lower BSFC at the same power output.

Higher octane doesn't mean squat unless you also mill the heads or otherwise increase the compression ratio.

I'm curious how you come to this conclusion...

nate

Easiest thing is to reset the trip odometer every time you fill up. Fuel consumption is miles driven since the last fillup divided by gallons added, modulo small differences in "fullness" (or liters divided by km driven if you want to do the metric reciprocal thing).

Best regards, Spehro Pefhany

Axle ratio should have been listed on the window sticker. It's also one of the codes on the glove box RPO sticker. Axle ratio can make a pretty large difference in performance and MPG. A vehicle hauling a lot of weight does better with a high ratio, while a low ratio is best for MPG, but hurts hauling performance.

As a comparison point, my K3500 DRW with 7.4 l engine and 4.56 axle ratio gets about 11 MPG moving it's 7,000# with or without the first few thousand pounds of cargo. Loaded with a 2,000# truck camper, 10,000# trailer and additional cargo to 20,000# gross, it gets about 9.5 MPG.

I don't have first hand experience with your model truck (I'm sure others here do), but I would expect it to get perhaps 16-18 MPG if it has the default low axle ratio. If it has a GVW under 10k it should have some EPA MPG estimate numbers (also on the window sticker) that should be reasonably close to what to expect.

I'd take a few weeks of filling the tank and logging the mileage to get an accurate MPG number and see where you really stand.

Wake up! What you came to know as "low-octane cheap mexican fuel" 40 years ago was better fuel than what most cars in America have in their tanks today. And yes that poor grade of fuel does have a lot to do with why ethanol improves mileage - that is correct.

The cars tested were modern fleet cars. Double blind studies so that they weren't influenced by driver's prejudices.

Or unless the fuel is really low octane without it. Most gasohol is only

87 octane. the fuel would be like 84 octane without it.

Because studies have shown that adding 10% ethanol does improve gas mileage in most modern vehicles - therefor for any one particular vehicle it is more likely it will increase mileage than decrease it. However, it is unlikely you will be able to find any reliable testing has been done on a fleet of 50 yr. old Studebakers.

-jim

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Global warming

Not a good idea, really. The in-tank electric fuel pumps that most manufacturers are using these days depend on a continuous flow of fuel to keep them cool. Repeatedly running the tank dry will dramatically shorten the life of the pump.

Almost 26%, actually. (25.6 to be precise)

Please note, however, that you're measuring miles per *tankful*. Not miles per

*gallon*. Has the amount of gas that you're pumping changed?

You *will* see better fuel mileage with synthetics, but not 26% better. Two to five percent, maybe, but not 26%.

a) Anything of that nature that was going to happen, already happened a year ago, and b) wouldn't make that much difference anyway.

You'd be the best judge of that. :-)

Additional explanations that you've overlooked:

4) Warmer weather. Yes, it *can* make that much difference. 5) Other maintenance done at the same time as the oil change, maybe something seemingly insignificant that you've forgotten about -- like making sure your tires are properly inflated. Yes, it *can* make that much difference. 6) If you always buy your gas at the same station, it's possible that they screwed up and put premium gas in the underground tank that's supposed to hold regular. If your fuel mileage suddenly drops back to its previous level, I'd be more inclined toward this explanation than any other. 7) *You've* been screwing up, and pumping premium instead of regular. OTOH, I'd think you'd have noticed this the first time, when you went to pay for it; seems unlikely you'd make that mistake three times in a row. 8) One really hot day, that raised the pressure inside the tank just enough to pop out a large dent. You're getting more miles per tankful because you're getting more *gallons* per tankful, but your miles per *gallon* hasn't changed.

snip---------

1. I think, based on a 93 suburban (e.g. same mfg) with the smaller engine that 16 mpg is optimistic - my suburban gets 16 on the freeway with people in it, traveling long distances but less in town.
2. thermostat makes a big difference - if the car doesn't come up to temp the computer keeps it running rich - (and it fails smog test) - you can see this in the exhaust gas analysis report - going from a 160 to a 180 deg thermostat made quite an improvement.

** Posted from **

And it only has a 22-gallon gas tank?????

I do not run out of fuel, I simply get to the point of fuel needle being at the bottom and low fuel warning.

It did not.

I agree.

I like the suggestion of a different blend of gas, personally. (change from winter to summer blend).

i

Yes. I would like to have a bigger tank.

Sadly, no.

I would love to see those studies. In all of the studies and tests I have seen adding alcohol decreases the mileage. Even the folks pushing ethanol admit to that.

A Suburban weighs more than a pickup.

Reprogramming the ECM so it goes closed loop with the 160 t-stat will also fix that problem, without running the engine too hot and cooking every wire and piece of plastic in the engine compartment.

Yea, 22 rather sucks. My 3500 has a 34 gal and it's not really adequate. I've been thinking about relocating the spare tire, installing a 30 gal Suburban tank there and replumbing to a dual tank setup. Still haven't got around to it though.