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a way to boost gas milage for older XJ's

T

ThE HiV

NAXJA Forum User
Location
VT
Hey. I have been thinking now that gas is over 4 dollars a gallon I need to try to make the XJ a little more efficient. I have a 93, which originally came with air conditioning. well it hasnt worked for a while, and i have no plans to get it working anytime soon. Im thinking that If I take out the AC compressor and buy a new belt to fit...that possibly i should get higher MPG's. Its one less thing the motor has to turn.

So my question is, has anyone done this, and if so, how much of a difference do you notice.
 
sounds like a good idea. might even increase HP too.

you could also delete the clutch fan and go to an electric fan. would be 2 less pulleys. let us know how it turns out.
 
ChrisRFewell said:
run your AC into your intake...more power and kinda like force induction, as well as better mpg maybe?
Click to expand...

have you actually done this. if so, i need pics.

i dont think the AC could put out enough PSI to make a difference. if it did it would be because of the cooler air. more like an intercooler than a turbo or supercharger.
that said i think you'd still see more benefit from removing that AC pulley from the equation.
 
I would think that if the A/C isn't running, then it is only as much drag as an idler pulley. HP gain shouldn't even be noticeable.
 
IGOCOMMANDO said:
I would think that if the A/C isn't running, then it is only as much drag as an idler pulley. HP gain shouldn't even be noticeable.
Click to expand...
that thought had crossed my mind but im sure theres some resistance especially as the unit gets older and worn out. over time it would gain more and more resistance.
 
ChrisRFewell said:
run your AC into your intake...more power and kinda like force induction, as well as better mpg maybe?
Click to expand...
HAha. seriously? do you know the CFM output of your AC fan vs the needed CFM for the intake? :wierd:

removing the AC compressor
converting from mechanical to electrical cooling fan
getting daily driving street tires vs mudders.
remove the roof rack if any
get a tune-up
better flowing air filter and exhaust
new o2 sensors
new cat (if the existing one is really really old)
 
Last edited:
Check out how you would need to run the new belt. I think other mods may be needed to make it work.
(IMO) If it helps at all the new belt will never pay for itself.
 
badron said:
Check out how you would need to run the new belt. I think other mods may be needed to make it work.
(IMO) If it helps at all the new belt will never pay for itself.
Click to expand...

people delete the a/c and mount the alt in its place so i know theres a belt that would fit.
 
Also, if you're just deleting the aircon, there's a factory pully (check the salvage yards...) that replaces the aircon pullly, so you don't need a different belt, and you don't have to figure out how to reroute it.

Removing the clutch fan has some merit - but you have to find a fairly hefty E-fan to replace it, because the 4.0L likes a lot of airflow over the radiator. It's doable, it's just not quite as simple as it looks at first.

Once you've removed the clutch fan, you can then remove the studs holding the pully and clutch on and replace them with capscrews (1/4"-20 by short, I believe,) and that will also gain you some clearance for the back of the fan.
 
ThE HiV said:
Hey. I have been thinking now that gas is over 4 dollars a gallon I need to try to make the XJ a little more efficient. I have a 93, which originally came with air conditioning. well it hasnt worked for a while, and i have no plans to get it working anytime soon. Im thinking that If I take out the AC compressor and buy a new belt to fit...that possibly i should get higher MPG's. Its one less thing the motor has to turn.

So my question is, has anyone done this, and if so, how much of a difference do you notice.
Click to expand...


By far and away, it has been shown that if you want to increase you mileage, the single largest factor is your driving habits; acceleration, overall speed, smoothness, etc.

Everything else, like what djblade311 listed will help, but the biggest factor is you. Just checking your tire pressure would probably have a greater impact than removing your A/C pulley.




.
 
I didn't get a good before and after result with my mech fan delete cause I went with the dual electrics upon stroker install. I feel that any way you can make the belt shorter and drive less things will lessen the load on the engine. I removed the mech fan pulley, did a lil grinding on the alt bracket and whatever the pointer thingy is by the 0* mark and used a smaller 2045mm belt. If I lived above NY or a place that didn't get above 90* then I wouldn't hesitate to remove the A/C, relocate the alternator and use an even smaller belt.
 
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