Thread: 4.0 - 4.6 Engine Upgrade

Hi Glenn,


I upgraded my 99 Auto Disco to a 4.6. In my case, I had two slipped liners, so rebuilding the old one probably wasn't an option. I purchased a brand new RR HSE 4.6, with a 12 month warranty, which turned out to be fortuitous. After a few kms with the new engine, I started getting a rattle which none of us could place. Sounded like a cross between very loose tappets and piston slap, and only happened during acceleration or decelleration. Quiet and smooth as silk at cruise. Anyway it got worse slowly and the supplier pulled the engine and found the crankshaft was moving axially. I didn't measure the movement but it seemed to be more than a couple of milimetres. The bearing shells showed a very strange set of stepped wear patterns. The supplier provided another brand new engine at no cost: even supplied a loaner car while the Disco was off the road. The new one is fabulous. The old one was disintegrating after 12,000 km.

Not sure whether the moral of the story is don't buy new in case you get a dud as I did, or do buy new and get the warranty.

As regards the rest of the vehicle, I have not done anything to the drive train, and I pull a caravan which is a bit over 2.5 tonne. I expect that the wear rate in the transmission will increase, and when it needs a rebuild, I will look at what can be done to upgrade the clutches etc, but there doesn't seem to be any reason to do so yet.

Whatever way you choose to do it, it is a very good upgrade. The extra torque from the longer stroke really transforms the car especially on hills.

Terry

Hi Glen,

I have now got the 4.6 upgrade in as well. To be honest I do not have anything to compare to as I bought the car with the motor stuffed, and replacing it was going to be the same price as either, rebuilding the existing one, or getting the 4.6, so the later was the obvious choice.

Nearly 10,000 k in so far so good. From a fuel consumption perspective I am not too sure what to expect, however I can get a variance of up to 100k dependent on the type of driving I am doing, eg HWY/City. Best so far is 475 Km out of a tank which was a mix of both so I am hoping the engine is starting to loosen up. the avg is around the 425km mark.

No changes made to anything else on the car, aside from a full service, fluid changes all round etc, and flush the radiator. I was told by Range Rov who did the conversion that no upgrades were required, as I assumed that maybe a bigger radiator was on the cards.

So far done a bit a 4WDing one day in mid 30's with aircon on, and no problem, car has been great (touch wood). I actually have had some of my best fuel economy on 4wding trips, even though the car has spent alot of time in low range, work that out........

I do think I have intermittent pinging when under load, eg going up a hill at a slow speed, but will bring that up at the next service.

The only other thing was I have been told to run it on premium unleaded only, so at an avg of 15cents more per litre you will need to factor that in.

The only downside is that you have a new engine running through old components, so there is driveline backlash there, and I am sure at some point the auto made need seeing to however I am hoping that is some time off, as said, car is running great.

The other benefit is technically you have a hand built motor not factory.

Cheers
JB

Trying not to be tooooo nosey and tell me to F@#* off if it's too personal, but what sort of dollars am I looking at for a new or rebuilt 4.6? I could comfortably install it myself and have access to a friends mechanics workshop whenever needed.

P.S. - I have a 2008 22foot RIB (Rigid Inflatable Boat) with 200HP and constantly am being asked whenever it's out of the shed "What did that cost ya" and it S$%t's me no end to the point that I now just walk away whenever asked.