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Gas Mileage Thread

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Wrench:
I have been getting around 12-13 on the highway, but I think that is due to a worn-out carb that doesnt atomize the fuel well.

'84 Cherokee 2.5, carbureted, AX5, 33" tires, 4.88 gears.

Jeffy:
So after after doing a 400 mile road trip, I've got some new numbers.  With a headwind and driving 70-75 mph, I get around 15 mpg.  If there is no headwind and I drive 60-65 mph I can get about 19-20 mpg.  No A/C this time.  Seeing the numbers I don't think A/C makes that much of a difference.  The real killer is the wind resistance.

 At 70-75 the Jeep gets a little sketchy in that you can feel the wind tossing the Jeep around.  Though it settles as you slow to below 70 mph.  My only real complaint is that my gas gauge doesn't always work so I'm using the trip meter to gauge how much as I have.  Problem is I usually have 4-6 gallons left in the tank when I'd rather have it closer to 2-3, about what's left when the gauge is on E.

There were two places where there were steep hills steep enough to have big rigs crawling at 40 mph, where I had to downshift into 3rd and rev it up (4K RPM) to hold 60 mph for several miles.

jfrabat:

--- Quote from: Jeffy on February 20, 2014, 12:58:58 PM ---I'd rather have it closer to 2-3, about what's left when the gauge is on E.

--- End quote ---

Maybe in YOUR rig...   :wall:

motorhedfred:
There's been some talk about hydrogen as a suppliment to gasoline on this thread and I'd like to add my 2. Most units are homemade as the commercial ones look the same as what you could put together from the isles og the Home Depot with a label on it. There's not much research data availible to the general public so we'll just consider this a fun experiment that might save you at the pump (or not).

One of the reasons people don't see the gains they were hoping for on fuel injected vehicles is they're not isolating the oxygen from the hydrogen. If you vent the oxygen to the atmosphere, the O2 sensors don't pick it up and therefore the ECM doesn't compensate with more fuel. Burning the hydrogen only richens the mixture as far as the O2 sensor is concerned which causes the ECM to pull fuel OUT to compensate.

While an HHO generator that can isolate the oxygen and vent it isn't as efficient because you need more space between the negative and positive sides, the difference in fuel economy should be substantial. One downside is, the hydrogen gas does displace some of the incoming atmosphere, but most onboard on demand type systems don't produce enough volume of gas to worry about that factor.....especially if you're not piping the oxygen into the intake. Water IS 1 part oxygen to 2 parts hydrogen after all !

MHF

sharpxmen:
you're right with the gains
but... theoretically, there's nothing wrong with pumping oxygen, you just press the gas pedal less (less need for oxygen from air) - remember that your fuel flow is related to the demand of power at a specific load, if you make power with something else then less need for gasoline+air (same thing with hybrids, the electric motor provides additional power so less need for fuel at times, or if you with going downhill - you can sustain the same speed with less gas pedal), but besides that you're right - all the on board H generators are not feasible, you replace the gasoline with some other fuel and it's not free regardless, plus it is probably negligible as far as quantity produced like you said.

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