Guys, I live in a country with no emissions regulation. How much is the impact of removing the catalytic converters in my Discovery in terms of gas mileage? Would it also help to change the exhaust system and put bigger tubes? Any idea?

I was getting very low gas mileage until I replaced the distributor cap. Now, It is better but still need to improve.

 

Yes it will help, how much? I dont know, but it will help.
A tune up will help too, that means new spark plugs and spark plug wires.

 

Cables, spark plugs and coil are new too...

 

Your oxygen sensors have alot to do with your fuel economy.
You have 2, if you remove your cats they will have no effect on the oxygen sensors.
So you can do both, replace your oxygen sensors and remove your cats.
Also installing a hi-flow style muffler will help.

 

Lots of people will say no way you cant..but im getting 17mpg calculated

 

Putting new O2's will give you the best result (unless you have a plugged cat). If you put exhaust that has a higher flow, you will need to match the intake and swap out the cam for more lift. The cheapest and easiest thing to do is to cut off your rear resonator and turn the pipe down. I would also pull the silencer trumpet from the airbox. It will be a little louder, but it will improve flow.

I would not suggest pulling cats. If you feel like there is too much restriction, put some high flow Magnaflow cats (or similar) on. You will not see much improvement unless you spend a lot of money on airflow..

 

Depends on how Rover set your emission system up, do you have 02 sensors, if so 2 or 4?
If you don't have any, you might pick up 1/2 or a little more MPG, can't say it is worth it though.
What octane gas are you running? Keep you air pressure up to around 40 PSI and you may pick up a little mileage.

 

I have 4 sensors and am using regular gas. I think it is 85 octanes (regular, not supreme).

The back resonator has already gone.

 

you may want to start by running proper fuel in that, they require premium, not regular, and 85 is way low for regular. as far as running more efficient without cats, i've got no cats on my mustang and i dont notice much a difference. run the right fuel and you'll get better millage.

 

First off, What year is it and do you know which market it was originally shipped to and sold in? That can make a difference as to what you can reasonably do with GEMS. I'll be crazy and assume it is North American Spec or Rest Of World since you are in Central America...

Second, definitely use a higher Octane gas... you will notice a difference in power and mpg.