Why the LS is a Major Improvement over a Top-Hat Rover V8
Updated: May 24, 2021
Once you drive an LS-powered Disco, you will find it hard to go back to a Disco with a Rover V8.
If you are looking at LS engine swaps for your Land Rover Discovery, then chances are you might be also looking at other Rover V8 options as well. In this article, I'll tell you why there is no point in sticking with the Rover V8.
I've sung my praises about how the Rover V8 was a great engine for its time, but it should have never been used as it was in the Discovery 2. As I laid out in another article, by the time the Discovery 2 was in production, the Rover V8 had a large assortment of different problems. While their are ways to fix some of these issues, improving a Rover 4.0/4.6 is sort of similar to putting lipstick on a pig. While it may cover up some of the bigger issues and improve the looks at a distance, underneath the Rover V8 is still a pig.
The block porosity problems and slipped liners of the late 4.6 engines can be fixed with "top-hat liners." This involves boring out the block to use liners that have a slight lip at the top. This lip allows the liner to seal against the head gasket so it cannot move, thus fixing the problem of the liners moving up and down with the pistons. This is a decent strategy – however, if the block is cracked and leaking coolant from behind the liner, changing to a top hat liner will not necessarily prevent the coolant from escaping into the combustion chamber or oil pan. Therefore, even with a top-hatted block, if you overheat after the liners are fitted and the block cracks, you can still end up with a unusable boat-anchor. Considering how much some charge for these top-hatted blocks, I find this to be troublesome.
To combat this problem, some manufacturers have fit top hat liners that are equipped with o-rings. These o-rings prevent coolant from entering places it shouldn't be even if the block cracks, essentially making the engine similar to a wet-sleeve configuration. This way if you have a bad overheat and the block does crack, your expensive top-hat block is not instantly worthless. However, such top-hat liners with o-rings are not a cheap solution and engines rebuilt with them are expensive. These top-hat engines alone can easily run more than the cost of our LS swap kit, all the necessary parts, and a low-mileage or refreshed LS engine.
Once your past the block porosity / liner issues, which have somewhat been addressed with the top-hat rebuilds, then there are the other issues with the Rover V8 that are often unaddressed. Let's start with head gaskets. Even with top-hat liners, the Rover V8 is still going to have a routine appetite for head gaskets. Some say that you can address these issues by using ARP bolts instead of the factory torque-to-yield bolts and that Cometic head gaskets can help reduce the need for gasket changes, but we've ultimately have found that really nothing can overcome the need to change the head gaskets. It's just the nature of the Rover V8 – an 80,000 to 100,000 mile maintenance routine.
Similarly the oil pumps and the cam bearings still have their issues. The old oil seal designs just don't work as good as newer designs. The Rover V8, no matter how nicely it is built, just cannot compete with the LS that is 40 years newer. Parts availability has also been a newfound issue for the Rover V8. We have been told from several sources that there are just simply no more decent "core" Rover V8 blocks, and that the current top-hat rebuilds from reputable manufacturers has significantly declined in recent months. Likewise, we've seen Rover V8 heads that have been resurfaced so many times by machine shops that they are completely unusable. Eventually, there will just be no more rebuildable Rover V8 parts. They will all be too far gone.
And for people contemplating used Rover V8s, the only question I have is – how much do you value your time? Sure, it might be cheaper – you might be able to get a used Discovery engine for a low cost – but when that engine develops some problem (which it will eventually in one way or another), your going to be back under the hood, fixing that old engine and putting good money after bad, while you could be off-roading or having other adventures in your Disco. Nothing's more expensive than a cheap Disco engine.
Probably my biggest gripe with rebuilding a Rover V8 is that once you get through all of those issues, you are left with the exact same engine as the Discovery had before. The 4.0 really lacks power with any sort of off-road equipment and the 4.6's power would be best described as barely adequate. While aftermarket cams can wake up the power a little bit, there is just no cheap and reliable way to get any more power out of the Rover V8. Enter the LS.
The LS gives the Discovery the power that it always should have had: passing – no longer need to wait for a 747 runway; highway on-ramp – smoothly accelerate with no kickdown needed; off-road – no constantly checking the temp gauge to verify you aren't overheating after clearing that last obstacle; driveway – clean. The best part of the LS is the piece of mind that you can push your Discovery without the fear of grenading the weakest part – the engine. I can't describe the feeling and confidence this gives the owner in the car.
We've heard too many stories about how the main owner of the Discovery wouldn't let their significant other drive the Disco alone; how they were afraid to go somewhere because something would happen and the engine would leave them stranded; or worse yet, the engine would overheat to molten levels, surely cracking the block. The LS takes that fear out of the equation.
Chances are if your looking at the conversion, you already know the merits of the LS engine: Wide availability, cheap parts, and stout construction just to name a few. The LS delivers smooth and comfortable power. Most people say that they can feel the extra power of the LS almost immediately after starting off in an LS Disco. Furthermore, the LS delivers better fuel economy, and we've actually seen up to 10-15% improvements on long trips, although that can depend on how your specific engine and Disco are setup. While the Rover V8 required premium fuel, most of the truck-derived LS engines are happy to use regular grade fuel, leading to further cost savings.
The Discovery has always been a vehicle with a lot of character. When people describe what their 'ultimate discovery' would look like, they mention a variety of upgrades, features, and personalization. Up to this point, many people just looked at the engine as a necessary evil. The engine always held the Discovery back. However, now, that doesn't have to be the case. The LS elevates the Discovery to a new level of 4wd, which puts it on the same playing field as some of the truly great adventure vehicles.