What is the minimum Octane I should be putting in my 2001 Discovery?

Thanks

 

91-93 i belive, but if it is cold there and your not having pining you can run the 89 or so.

 

you should no lower than 91 octane 89 is ok but you won't get the mileage and perfomance with 93 plus it's make's the engine last longer.

 

premium or 93-91 octane 89 is ok but you will lose a little mileage and perfomance with 89 so stick with the premium it make the engine last you forever.

 

BS...I have found no difference in 89 or 92/93 octane regarding mileage, in two different D1 disco's. I run 89 now, with no issues. Premium is recommended because of the sticky valve issues found on the GEM's motors. But, regardless, sooner or later the heads will need to be rebuilt anyway, so the extra cash for high test is not worth it.

Lets say you fill up with 18 gallons; High-Test is $0.10 more per gallon verses Mid-Grade. So, that's $1.80 more per fill-up.

Having your heads rebuilt (if you do it yourself) will cost you under $500.00. ($100.00 for a valve job on both heads, plus new valve seals, gaskets, fluids, etc....)

$1.80 goes into $500.00, 277 times. So, that would mean you need to fill-up 277 MORE times for High-Test to save you any money. So, if you get 12MPG, Times, 18 Gallons of gas, you can go 216 miles. 216 miles per tank, Times, 277 fill-up is 59,832 miles.

So, is high-test going to make your truck last 60k more miles? Not likley......

Just my .02

 

I agree with hank, no milage gain from highter octane. If you get pinging with low octane then yes you will need to step up the points.

 

Yes, it is true that 92/93 octane was needed for sticky exhaust valves.
I will take everyone's word on the mileage.
But the octane requirement is not only for the heads, it is for a sleeved aluminum motor.
As long as the knock sensors are working, anyone can run any octane they want. (I would not)
You will only lose horsepower.
What happens just before the knock sensors kick in is you get that diesel rattle.
Sometimes you can hear it, most time you will not.
How much of this can a motor take before it drops a sleeve is something I'm not willing to find out.

If anyone wants good fuel economy why would anyone buy a LR, RR.

We all know why we bought them, and it was not for the fuel economy.

The only thing I want is a larger fuel tank, could I get a forty with that?[sm=icon_cheers.gif]

 

Due to headers, I do not run a knock sensor on one side. I have not noticed any problems other than running rich at start-up...

 

Your not gonna loose horsepower, the noise you call diesel rattle, is detonation. (pinging). Horsepower wise, you want to run the lowest octane you can get away with, thats whre the horsepower comes in to play.

 

Higher octane fuel is a slower burning. This allows a higher compression engine to advance timing without pre-detonation, thus allowing you to utilize higher HP output. Low octane fuels burn faster, hotter, and more efficiently. A higher compression engine backs off timing thus lowering potential HP, at the same time adding more fuel to compensate as said above, knocking/pinging/pre-detonation. Mind you, the addition of the extra fuel is very minimal. Our engines don't have that high compression, I don't know why people are so crazy about high octane, besides some of the benefits of the other solvents they put in to clean injectors and higher methanol quantities to prevent freezing.

Most people that actually see a positive performance difference using high octane have bad 02 sensors throwing the ECU in closed loop (default), high injector duty cycles. 02 sensors don't work properly after 30k-50k anyway. I don't think detonation could ever cause a sleeve drop as these are made with an interference fit (at .002-.003" over), the hotter they get, the stronger they hold. Blowing a hole in a piston, now that's where you can pont fingers at detonation.

High octane fuels are a waste of money in my opinion. I'd rather dump in half a gallon of methyl hydrate per fill up to do the same thing.

I love engines way to much! [sm=burnout.gif]