hey thanks man, ill check that out!

 

So we're almost in the same boat then, intersted to hear what people think about this one

 

Like riding a 10 speed bike, shift to a higher gear (taller tires), it becomes harder to pedal. The XJ is NOT a torque monster, it has to work harder to turn taller tires (as with most vehicles).......mpg and performance suffer. But hey, they look cool and go over big rocks better.

 

when youve got the right gear set for your tires (in which you pretty good off with 3.55 if you have an auto with o/d go for 4.10) but by having the correct gears in will make ur xj as efficient as it can get with larger tires

 

Maybe a Noob question, but what is this?

 

It's a vacuum gauge.......it tells u when your right foot is at the correct position for best mpg. Like I said, u keep the needle at 15 or higher, u'll see better mpg.

 

Let me know when you do. Ill order one too, maybe make the trip down to Olympia

 

Drive like you have an egg under your right foot. Big tires and a big foot kills MPG. Keep it under 70 on the interstate. My 99 stock gets around 20 on the highway. My wifes new Liberty gets about 23 on the interstate. We have had Grand Cherokee 4.0, Commander V8, Liberty 3.6 and of course my Cherokee and all of them got 19 - 23 MPG on the Highway.

 

Does anybody think cutting 2 holes in the hood and putting on vent covers to get more air flow through the engine compartment. In turn it will help keep the engine cooler and in turn get better milage?

 

I am interested in updating exaust but that kink in the head pipe after the manifold flange seems like a killer to flow. So I question the benefits of catbacks or changing manifold.

 

If you want AWESOME mpg savings on a Jeep XJ, the only suggestion I can give is to do this mod.

http://www.driveev.com/jeepev/home.php

Jeep XJ's are fat ladies, and where they lack in Obama's and Gore's philosophy of saving the planet, they make up in their ability to get ANYONE or ANYTHING out of a sticky situation.

I cant wait for the day to come where I'm drivin down the road in my XJ and I see Al Gore stuck in some mud with his smart car asking for help.

 

Don't know that an XJ is a fat lady........at +/-2900 lbs they're one of the lightest SUVs on the road, about 350 lbs lighter than a 'vette. Just think, a measly 300HP 4.8L EFI LS1 and your talking muscle car power-to-weight ratio and close to 30 mpg and way more fun to drive than an electric golf cart. LOL

 

This I can agree with. Personally, I don't think the gas mileage increase you get by swapping out for a new cat back, new header, and new intake will ever be recovered in fuel savings. You're talking hundreds of dollars here. Let's say the whole job cost $500. You would have to spend almost $3500 on gas to break even if you got 15% fuel mileage increase. And that is a big, big IF. Probably more like 8% is realistic...which means you'd have to spend $7,000 on gas to break even.

And is you are NORMAL...you will use the added horsepower to enjoy the car more, not save money.

He's right. If you want to save money, buy a vacuum gauge. If you want to have fun, buy some cool parts.

I don't have a vacuum gauge. I gave it to Obama. He's using it to see how bad he sucks.

 

by putting on a complete exhaust system with headers you will free up a good bit of h/p and everyone knows more h/p =better gas mileage

 

do the manual to electic fan swap. i noticed most increase from it. its cost me about $60.

think about it, manual fan is 6.5 lbs spinning all the time. electric only spins when it needs to. when it is spinning there is a greater load on the alt which negates the effect of not having it spinning at all times but still makes a big difference and keeps the jeep cooler.

i also installed bigger alt at same time