None of the following propositions are guaranteed to work. If you want a guarantee, contact JE Engineering ...and pay their prices!
They exits in various displacements and feeding methods, all interchangeable with a little bit of creative effort. Standard is 3.5 and 3.9. Other factory installed ones are 4.0, 4.2 and 4.6. The engine's roots are in the 215 cid Buick engines that GM abondoned in 1963. In 1965 Rover found that it was exactly the engine they could use in their car line and bought the tooling.
Compression ratios are 8.13:1 on early versions and 9.35:1 on later ones. Higher compression ratios are available as 10.5:1 but you loose the possibility to run on bad fuel.
Intake systems range from carburated to multi-point fuel injections. You can switch to fuel injection if you can find a complete system but make sure the computer (ECU) is still ok. Most systems are sold for this reason. Computers CAN be repaired ...sometimes. You will not get too much power improvement but running at low and high rpm's is much better and fuel consumption goes down about 10-15%. Trade-off is that you will have a more complicated system with parts you can't fix in the field. The ECU can be reprogrammed using another chip. With an adjustable fuel pressure regulator (from RPI, UK) you will get much better acceleration.
An interesting variant is the Vitesse engine. It has a tad over 200 horses although on the paper they seem at too high rpm's. In real world it's very driveable.
If swapping any Rover V8 be very careful that the engine you want to put in is really in good shape as they are prone to internal wear if not well maintained. Oh yes, they can run forever even if worn down but it makes no sense to put in a mill that only gives 80% of it's power.
Generally I'd say it doesn't make too much sense to swap for example an 4.2 in place of an 3.9 unless your engine is tired and you get a terrible good deal. On newer engines make sure you get ALL the electronic sensors and wiring, including oxygen sensors and the in-tank pump
The best tip I can give is to read the book "The Rover V8 Engine" and get advice from a reputable source as RPI or JE.
|The 4.6 as in the latest Range Rovers is a nice engine with high output but it relies on lots of electronics. Fine for a road going car but not for your usual mud-plugging and road-running 4x4. Oh, sure, it has several limp-home modes but I see no sense in running 80% of the time in this mode as contacts corode and sensors decay.|
Modifying your engine is easy. The biggest change in any engine is the camshaft as it regulates the intake and output of your motor. The factory cams are on the very tame side as they are suitable for many applications, from towing to high speeds. You can put an 3.9 EFI cam into your 3.5 without getting bad values in any department. Or you can go to an aftermarket cam, eg from Crane. Don't go too far if you want to keep everyday driveability. But any cammaker will help you on this.
If you change your cam, you MUST also change lifters. You SHOULD also change timing gear and chain which is only just suitable from the start. You also have the option of changing to a complete gear setup.
Other performance parts are also available as valve springs, roller rockers etc but are of little interest if you don't want to squeeze every bit out of the engine.
Early V8's had a point-distributor system, quite ordinary and easy to fix. Later LUCAS systems were electronic and adequate. Hot setups are available from Jacobs (USA). An point-type waterproof system was used in military applications and can be had as an aftermarket kit. But it's expensive and hard to find. Expect to pay about 10x the standard price for a spark plug.
Oiling is marginal so it pays to use high quality oil filters. Cheap filters can flow up to .5 bar less. If you have low oil pressure over all rpm's it's likely your main crank and cam bearings are worn. Higher rated pumps are available as aftermarket items.
RPI, and numerous others
200 and 300 TDi
Power upgrades for the Diesels are more limited than for the V8's. Both engines have similar power and torque readings, the 200 being a little noisier but also a bit lower in consumption. Power upgrades concentrate rather on intake than on the exhaust side.
The engines are intercooled, which means the air is cooled after having been compressed in the turbocharger. Cooler air means more oxigen and so more available power- it's as simple as that. The factory air cooler is only very small, taking about 1/3th of the available space. The other 2/3ths are shared between the radiator and oil cooler. Aftermarket intercoolers typically stretch over the full wide of the radiator in front of this so lowering the intake air temperature remendously- from about 85°C to 35°C. Adding to this an adjustment of the fuel pump needed to get the correct mix and a very slight rise of turbo pressure you get around 140 horses and torque figures similar or above the 3.9 EFI's. All this for 60% of the fuel consumed.
Only an adjustment of the fuel pump will give you an considerable power increase in an otherwise stock engine. It's an easy thing to do- if you know what you're doing. If you don't I will not tell you as you will certainly ruin your engine. Drawback of this is an increase in black smoke. Appproximative you will get 10 more horses.
More exotic modifications are watercooled turbochargers, a different camshaft etc. But leave this for specialists like WBH (Warwick-Banks-Handling) or similar. The 140 horses mentioned above are all you will need and engine life seems not to be affected.
Air Intake, V8 and diesel
You can buy K&N air filters for carburated or EFI versions as well as the diesels. Beware however if you mount an external air intake (snorkel). You MUST use an air filter, the intake prefilter systems fitted on some is only this- a prefilter. Those systems are great as they give you cleaner and cooler air to start with- so rising power and filter life. But power goes down with the lenght of intake path as resistance to air flow increases.
Make absolutely sure your snorkel is mounted professionally. A common error is ignoring the (almost invisible) gap between outside flange and the inside air box. This is more dangerous as no snorkel at all. Trust me. Alos some companies, like Mantec, offer extension kits to rise your axle and gearbox breathers to the same height.
Snorkels are made by:
MANTEC, Safari (Australia), Southdown (UK, well known), W&H Wheelcarriers (mild steel and stainless) and others.
The factory exhaust system is... well, simple. No specials, no refinement. But quite cheap to replace (well, most of it). If you want to be quite for many years get an stainless steel system. They aren't much more expensive than mild steel and last way longer. An power increase is noticeable on V8 systems, diesels show much less. This is due to the turbochargers being the most restrictive parts.