LUVTruck.com

Hello!

This board has been a wonderful source of knowledge and help for me. I am grateful and happy to be a member here!

I have some questions regarding fuel mileage.

I am very anal about getting every last little inch out of a gallon of gas-and when I found out this truck is easily capable of 30 MPG (As a 4x4-amazing!) I wanted to work even harder to get more per gallon.

So, what upgrades and options increase mileage? I am not so worried about performance-the engine is a mild, slow unit that is dead reliable.

The Weber carburetor everyone talks about: I have heard mileage goes down with it. Is this true?

How about the Offenheiser [sic] intake? Does mileage go up or down on a stock LUV?

Exhaust hearders: More gas flow means more fuel flow-however you have to give the motor less gas to stay going, so does it balance out? int he end, does the truck get better MPG when you drive it normally? (not like a racecar, and not like Grandma)

Of course the 5 speed conversion, that really should bump my mileage up, as the engine seems to be screaming to keep up at 55 MPH sometimes. What sort of MPG upgrade on level road @55 would I expect with that .2 gear ratio difference?


I thank everyone for their wisdom and answers.

The 5spd would be the single best mileage upgrade. I'm not sure what to expect exactly, but i'd guess in the range of 2-4MPG, on the higher end of that or more for all freeway driving. The weber, header and other performance upgrades can improve mileage but you have to alter your driving habits to get the benefits. If you drive with your foot on the floor all the time, the perf. upgrades just suck down more gas but get you there faster, balancing out to about the same. I got a solid 1-2MPG better out of my weber, but only when I drove the whole tank concentrating on keeping my foot out of it.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Well , not exactly an upgrade but at work we have a nitrogen tire inflator. The nitrogen keeps pressure longer.

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1980 Chevy LUV

What about a high flow catalytic converter?

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

I'd say free flowing exhaust, free flowing intake filter, advance timing to just before pinking, keep tires at max inflation, no dragging calipers or shoes, adjust carb for 'Lean Best' fuel balance, use a good thermostat to maintain engine temperature. I threw a switch in the circuit for my heat/ventilation so I could shut fan off completely instead of it running all the time, slightly less parasytic load on alternator.

Headers never penalize gas mileage because of the LUV cam profile. There's a little valve overlap but that just aids in drawing in fresh mixture and doesn't decrease mileage. My Weber in 2 different setups cost me just a little mileage but I agree it's worth it for a bit more power. I doubt a Weber alone would ever increase MPG, but as mentioned maybe it would with other upgrades.

The single best gas mileage improvement on any of our rigs is a vacuum gauge. That is a constant reminder of how hard your foot is on the pedal and you can precisely control mileage and power. Usually pretty cheap, easy to install and pays for itself in no time

Wheredo you install the vaccum guage? There are a lot of hoses to choose from.
If you or anyone else has a picture please post one. Thanks!

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

Yeah, i am interested in the vacuum gauge.

More vacuum means more foot in the pedal?

I also have a super high voltage Mallory ingition coil that lets me use the truck like a tractor with lots of lwo end torque. I would think that would help mileage...

Yes, the wider the throttle blades are open the more vacuum is registered on gauge. It's pretty amazing to watch, 'cause it often doesn't seem like you're pushing that hard. One of the best parts is you can gradually let up until vacuum number drops and drops and then when vehicle actually slows just add a wee bit more, at best throttle position for what you're doing. Almost anybody's mileage will improve by knowing what's really going on!

I've had vacuum gauges on every motorhome I've had, it makes a huge difference in mileage for that type of rig. They pay for themselves in short order when you're able to 'tune your foot'...

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

I'm sorry, I somehow missed the 'How' questions!

It's dumb simple, just tee into any manifold vacuum line and run a line to back of vacuum gauge. The vacuum gauge does not consume or change vacuum in any way, just measures relative vacuum in engine. There's also some lines that go to charcoal cannister, fuel return etc. so be sure you're using a vacuum line, attached to intake manifold.

Any auto parts store should have a tee fitting.

On my '75 there's a great big fitting for EGR just below carb on side of intake manifold toward driver fender. 3 or 4 vacuum lines are connected there. Tee in and add one more and you've got it. There's also a vacuum line on my firewall that's connected to intake. Best not to tap into the single vacuum line that provides distributor vacuum advance. Shouldn't hurt but possibly readings would fluctuate at lower rpm's.

Headers cost money, so do carbs, so do 5 speeds, so do most things.
Ive found, leaving earlier and driving slower are by far the best ways to save fuel. Best thing is its free.


I just poke along most of the time. No need to be in a hurry.


My old truck is pretty economical. The fuel pump has packed it in, it will keep up with about 1/4 throttle, its economical but its as frustrating as hell. It coughs and farts and i just have to keep lifting my foot.



Bob.

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Current project, 1979 KB Isuzu Ute.

Daily driver, '86 Rodeo Spacecab.
Chasing parts for Isuzu Impulse.

Free is nice. However the next best thing is cheap. Being in the right place, at the right time, I've gottend some pretty cheap parts.

So with the Vacuum guage, do they come in with different size fitting for the hoses?
How about different brands?

JC Whitney has these...$30 and shipping, and you'd get that back in a couple of tanks...

http://www.jcwhitney.com/autoparts/Prod ... llon+gauge

Here's some ricer stuff that might work too...
http://www.glowshiftdirect.com/vacuum-g ... agodRjbSiQ

Most boost gauges measure both PSI and Hg in. for vacuum/pressure. You might even be able to pick up a used one on Craiglist. You'd only use 1/2 the gauge, but I doubt you'd need anything that read above 30...

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

All usually come with necessary fittings to fit standard 1/8" vacuum line whether rubber line or copper. You may need to pick up a tee to cut into an existing vacuum line, best to NOT use the distributor vacuum advance hose as vacuum source.