All fuel injected engines use knock sensors.
They will adjust the engine timing as much as needed to prevent spark knock so as to preserve the engine no matter the performance or MPG loss.
Even though you cannot hear spark knock does not mean that it is not happening.

 

TDI... I remember my mother having a Volvo 850 TDI in Europe... LOVED IT! And yes, if they would be easier to find, that would have been something to consider! So, would anybody recommend not doing such a thing with a 4.6L? Also, I heard that with the TDI you can wade through deeper waters, is that true? Would a snorkel do anything for non-diesel discos aside from getting cleaner air from high up?

BTW, I drove from LA to Denver for New Year's and last weekend we drove out to Phoenix. Long distances that really allowed me to check on the MPG. Doing about 75-80 most of the time, I got around 15 MPG on premium. That includes going through the Rockies though... I bet that when going 70-75 you could easily get 16MPG..., that is just so hard...

 

Sorry Spike, heavy spark knock can be heard and felt by any driver. Light spark knock can also be heard by a technician or an engine expert. So, if you cannot hear it, it is not there.

To test this statement, hook up your OBD II diagnostics tester (I use a Vetronix / Bosch Mastertech) and drive any vehicle that is exhibiting occasional spark knock.

In the data list, you will see that the ECU will retard your timing advance when you hear heavy spark knock, it will not retard under light occassional spark knock.

I am reading the Fuel sections in my owners manuals for the 2000 SD (page 89) and the 2004 SE7 (page 115).

2000 SD(Page 115): "Premium unleaded (90 - 92) should be used whenever possible. However lower octane fuels can be used but performance and economy may be reduced." NOTE:" Occasional, light, engine knock experienced ONLY for short periods while accelerating or climbing hills is acceptable."

When Land Rover talks about lower octane fuels, they are thinking about cut gasoline mixed with kerosene or diesel that you get in easten or central africa or central asia.

The Land Rover brand was not designed to compete with a mercury sable wagon on our speed limited highways. Land Rovers were designed to drive around the world under any condition, handling any type of fuel. It is why they use a low compression pushrod V8.

So as I stated previously, the 2004 SE7 will go on a premium diet and I will report my MPG in 5 K Miles.

The 2000 SD, I am sure that it will go another 80 K miles the way it has done on 87 octane and it will still run as good as new. The reason: I maintain it religiously...

 

I live in Oklahoma and the best gas I can find is 91 octane...

Does anyone know of a good resource online to find a gas station with 92 or 93 octane??

 

Check this out: http://www.oklahomacitygasprices.com/index.aspx?fuel=C

Typically, BP & Texaco carry the higher octane premium. I have to use that in the M5 to generate the 400 HP at 7000 RPM and keep the pistons in the cylinders at 11 to 1 compression.

 

The reason TDIs can wade through such deep water is that they don't have any ECUs. A snorkel does help a gas Disco (or any truck for that matter) but if you plan on going through water REALLY deep you should really look into water proofing anything electronic that's under the hood, and you also need to extend the breather tubes up to the top of the snorkel. I'll be doing all of this to my truck hopefully before summer

 

You make a great point. I know people on job assignment in eastern Africa that operate the Disco (V8 gas and 5 speed manual) right next to the Nissan Patrol and the Toyota landcruiser.

The D1 does great and it is the top choice for long distance travel, much more comfortable with better suspension articulation.

For gas, it is first come first serve with 5 gallon jerry cans or improvised hand pumps from larger tanks.

So, you did the right thing buying and owning a Disco.

 

Anybody have any suggestions on how to waterproof the under hood electronics? Specifically the ECU.