Mechanical and Electrical Upgrades


IntroductionRange Rover in Extended Profile
Air Conditioning Upgrade
Air Intake Filter & Box Upgrade for More Horsepower (P38)
Air Intake Upgrade for LPG Range Rovers (P38)
Air Supply for Tire Inflation (tapping into EAS)
ARB Air compressor for tire inflation
Air Suspension:

          Arnott Generation III Air Spring Upgrade: firm highway/soft off-road & more travel
        Converting to Coils
        Cross-Linking the Air Suspension for Off Road Ride & Traction
        Extended Profile Selector (P38)        
        Emergency Manual Operation/ECU Bypass       
        Lifting the Air Suspension
        Lifting EAS Using Recalibration

        Replacing with Coil Springs?? (Classic, P38)
        Replumbing the Air Lines for Manual Operation
        Shock Replacement with Bilsteins (P38)
        Shock Replacement with Adjustable Konis (P38)
        Sway Bar Disconnects
        Tapping into the Air Supply for Tire Inflation etc
        Tapping into Air Supply (Hardy Neale's Approach)
Alternator: Conversion to Delco Generic models
Alternator: Conversion to Bosch Generic models
Ash Tray (rear) Upgrade to Wood Veneer (P38)
Audio & Entertainment System Upgrades
Battery Back-up (Dual) Installation (Classic, P38, Mk III)

Battery Upgrade to Optima Red Top (P38)
Backup Light Upgrade (Classic)
Body Side Trim Molding Upgrade (Classic)
Body Side Molding Upgrades to Chrome 2001-2 Spec
Body Side Vents (Power Vents) from RR Sport Added to P38
Body Moldings (Mk III)
Cargo Net Installation (P38)
"Chipping" the engine (All)
Coil Spring Conversions (Classsic, P38)
Coil Spring Upgrade (Classic)

Compressed Air Supply Installation (All EAS Models)
Cubby Box Lid Upgrade to Leather Trim (P38)
Customizing Range Rovers (P38, Mk III)
Diesel and LPG Conversions

Dog Guard Installation or Removal (All)
EFI Upgrades (Classic and P38)
Electrical Connection Improvements
Electrical Wiring Through the Firewall (P38)
Engine Swaps/Upgrades using Rover V8s (Classic, P38)

Engine Power Boost (Classic, P38)
Engine Power Boost (P38, Mk III/4.4)
Engine Upgrades, other (Mk III RR)
Engine Swaps using GM & Ford Engines (All)
Engine Swap (Diesel) (Classic)
Entertainment System Upgrades
Exhaust Upgrades (Classic, P38)

Exhaust Upgrade (RR III) for ground clearance & power output
Exterior Customization (P38, Mk III 4.4)
Fuel Filler Lid Switch Fix/Upgrade (P38)
Front Diff Problem Permanent Cure using Custom Driveshaft (RR III)
Gearing Changes (Classic, P38)

Grille Upgrades
Handbrake Handle Upgrade (P38)
Headlight Conversion P38 to 4.4
Headlight Wiper Upgrade (P38)
Ignition Upgrade to MSD Ignition (Classic)
Interior Customization (P38, Mk III 4.4)
iPod Interfaces for Range Rover Stereos
Lighting Upgrades

Loadspace Anchor Points and Tiedowns (P38)
Loadspace 12 and 110 V Power Outlet Install
MSD Ignition Installation (Classic)
Navigation System Upgrades (RR III/L322/4.4)
Parking Brake Handle Upgrade
Power Outlets (12V and 110V) Installation in Loadspace
Power Upgrades (SVC) (P38, Mk III 4.4)
Power Upgrades (Overfinch)
Power Upgrade from Improved Intake Air Flow
Power Upgrade from Rechipping
Power Vents from RR Sport Added to P38/P38
Radiator Grille Upgrades (P38)
Seat Belt Buzzer, Silencing (P38)

Shocks (P38)
Snorkel Installation (P38)

Steering Stabilizer Upgrade (P38)
Stereo -- iPod Interface
Suspension/Handling Upgrades (P38, Mk III 4.4)
Supercharging
Sway Bar Disconnects (Classsic, P38)
Third Row Seat (Mk III)
Trailer Wiring
Wheel Arch Trimming for Bigger Tires
Wiring: Running Cables through the Firewall (P38)
Wood Veneer Ash Tray (P38)
More Information

                                                                          (Photo: Manual Selection of Extended Profile)
Introduction

The pages on Common Range Rover Problems and Fixes, Range Rover P38 Problems and Fixes and Range Rover Mk III Common Problems and Fixes cover "how-tos" on many of the things that frequently go wrong. The Maintenance Operations pages cover routine maintenance tasks, and the pages on Repair Operation Details  cover certain repair operations in more detail with tips to supplement the shop manual. This "Upgrades" section of the site is intended to cover mechanical and electrical upgrades for your Range Rover, not to be found in any official manual.

 

Air Conditioning Upgrade to CFC-Free Refrigerant

Conversion of Range Rover Classic air conditioning systems to the new CFC-free refrigerants (R134a) is not too difficult, and does not appear to result in noticeable loss of cooling performance. Larry Michelon has contributed details of this procedure on our A/C Upgrade page at this link.

James Howard has also done this operation on his 89 RR; he has some info on the conversion on his site at this link.

 

Air Suspension: Extended Profile Selector (P38)

The air suspension's Extended Profile mode, which raises the vehicle another 1.2 inches above High Profile, cannot be selected under driver control; it can only be selected automatically by the suspension ECU when it senses the vehicle is grounded. It can also be selected by the dealer's "Testbook" to make working under the vehicle more convenient. To overcome my frustration about this, I devised a way of raising the suspension to any desired extent manually at the flick of a switch.

Full details of this modification appear on the Extended Profile Selector page.

For more information on Range Rover suspensions, see Suspension Details and Modifications.

Air Suspension: Emergency Manual Operation/Bypassing the ECU (Classic, P38)

Many owners are afraid of the consequences of getting an EAS error when out in the boonies, resulting in a rough ride home on the bump stops. If this happens it is theoretically possible to bypass the EAS controls and control the inflation of the air springs manually. One company, Motorcars Ltd even makes an Air Valve Conversion Kit designed to restore your air springs to a comfortable ride height if your EAS develops a problem. Their kit fits both Classic and P38 Range Rovers with air suspension. As long as the air springs and air lines are in good condition, the kit allows you to bypass the Electronic Air Suspension ECU, air compressor and valve block should any of them fail. You can air up the conversion kit with a convenient source of compressed air or portable electric air pump. More recently, a lower cost kit has become available from Justin Tiemeyer; see the Manual Air Recovery System page.

Another approach is being tried by Bill O'Brien, who has modified his Classic LWB air system to allow airing up each corner of the vehicle manually when the computer goes into a "code" status with flashing lights at the upper and lower buttons. He is planning to put together a kit with air valves and tees that work with the 6mm line, along with complete instructions on how and where to cut lines and unplug temporarily the computer. His system brings a Schrader air valve to each wheel and all you need to adjust ride height is a tape measure. He estimates the cost at $100 with all necessary parts and instructions.

For more details on these and other approaches, see the main Air Suspension Information page and the special page on manual operation of the air suspension.

Air Suspension: Lifting

Many assume the air suspension cannot be lifted in the conventional sense. It can, and details appear on our "Lifting the Air Suspension" page.

Alternative methods of getting more lift include the manual Extended Profile Selector described above, and simple recalibration of the default suspension settings as described below to give more lift off road.

Air Suspension: Recalibrating for More Lift
(For complete information see the Air Suspension Recalibration Page)

Another method of getting more lift out of air suspension models is purely electronic -- you can change the default height settings in the air suspension's ECU using the TestBook or the aftermarket equivalents now available at much lower cost. Hardy Neale reports that some time ago he read with great interest your articles on extended profile selection & re-calibrating the height settings. He initially hat the height settings on his '99 4.0 EAS re-set by Rick's 4WD as follows:

Freeway - default
Standard - 15mm higher (room for Cooper ST 255/70 x 16 tyres)
High - 30mm higher, the full whack - emulates emergency extended setting.
Extended - default

The procedure did not even involve setting blocks under axles etc -- Hardy's mechanic simply plugged his computer (Autologic, not LR TestBook) in and increased existing settings by above values in 5 minutes with the car parked in the driveway. "Each airbag has a specified setting for the different heights; I just asked Rick to increase the existing values by 15 and 25 mm." He reports having no troubles since -- and this method does bypass the problem with the EAS bypass circuit I developed in that you cannot accidentally go higher than the standard "Extended" mode and run the risk of popping the bags. Hardy reports his friends are rather impressed with his extra lift selectable at the press of a button -- his "high" mode is over 2.5 inches above the default "standard" setting.

At these extreme height settings, ride quality and articulation do deteriorate noticeably, so the particular tradeoff you use is up to you. As always, use at your own risk!! 
 

Backup Light Upgrade (Classic)

The Classic Range Rover, like most vehicles of its era, has backup lights that are mainly decorative -- it is often necessary to keep the brakes on to illuminate what is behind you. Jim Lupinetti discovered that Susquehanna Motor Sports of Stewartstown, PA has a Hella Backup Light Halogenization Kit, Hella P/N 81140. It includes 2 each Hella P/N 78165 bulbs, 12V 20W Halogen, which plug into a BA9s base, and two adapters to convert standard BA15s base to BA9s base.  The kit price is about $25. Installation is as easy as replacing a bulb, and gives about twice the stock illumination with no change in power rating.

 

Coil Spring Upgrade

The shop manual gives the part numbers and specs of the springs used on the Range Rover. To correct the usual lean to the right suffered by most pre-sway bar Range Rovers in the US, you can replace the rear springs with two left hand units (the left spring is slightly longer than the right).

For those wanting to experiment with various different springs on their Range Rovers, it is good to know that all Land Rover coil springs are interchangeable in terms of fit. There is a listing of Land Rover springs, part numbers, spring rates and lengths on the Four Wheeler web site. However it does not state which springs are constant rate and which are variable rate -- only a single rate is given for each. I wanted to try the NRC4304 on the rear but sold my Classic before I had a chance.

In terms of aftermarket springs, unfortunately nearly all combine increased height with increased stiffness. An exception is a special set of springs available from SafariGard. Another set from DAP gives about an inch of lift with minimal stiffness increase.

For more information on suspension upgrades, see the Suspension Details and Mods page.

 

Diesel and LPG Conversions

In many countries diesel fuel is much less expensive than gasoline (petrol), and diesel conversions may pay for themselves. Gavin Reynolds details his procedure for putting an Isuzu diesel into his NAS (Canadian) 1991 Range Rover Classic on the Classic Diesel Conversion page. For another diesel engine swap, see Matthew Reeve's example. In the US, there is little differential in fuel costs and installing a diesel would almost certainly not pay for itself in fuel savings.

In the UK and Australia where petrol/gasoline is very expensive, LPG conversions are also fairly popular -- for more information see the LPG conversion page on the RPI Engineering site. Also see the P38 Airbox Upgrade page to make your air intake more robust to avoid having it destroyed by the occasional backfire.
 

EFI Upgrades / Rechipping (Classic and P38)

It is possible to "re-chip" Rover V8 engines to produce about 10-15% more power. Most factory settings for fuel delivery and ignition timing etc are conservative, and reflect similar programming skill to the EAS ECU that is notorious for its stupidity. Aftermarket ECU makers take advantage of this by replacing the factory settings with more intelligent ones. 

 

P38 Options
The most popular and proven option for the P38 is the Tornado Systems chipset. This is a two-chip ECU set to upgrade the GEMS software on the 4.0 and 4.6 Rover V8s. When used on a 4.0 engine, it is said to raise performance to match a 4.6 without any other mods. It is also intended for use when upgrading a 4.0 to a 4.6  V8. It has long been the cornerstone of Range Rover engine upgrades by RPI Engineering (whose US agents are East Coast Rover). 
Ian Dugdale reports his very positive experience with RPI's Tornado chip installation: "There is a design flaw in the engine mapping for the GEMS 4.0 and 4.6 units, where the engine runs lean at low revs (done by LR to improve fuel economy). In the 4.0 it's not such a problem because the lesser power of these units means that hey are more frequently kicked down into a richer area of the mapping, but the 4.6 will suffer more because it tends to run more in the low rev range, resulting in excessive heat buildup, and on to cracking of the block. This can be diagnosed by unexplainable usage of water, and as it progresses, a puff of smoke when starting in the mornings. The Tornado chip, apart from adding more power, remaps to avoid this lean running". The Tornado chip used to be available only through RPI, but recently Tornado Systems has been setting up a worldwide direct distribution system. For more information please see the  Tornado Power Chips and EFI Upgrades page.

You can also get a chip set from Superchips UK. They are a general purpose rechipping company who cover most brands of vehicle, so are not specialized in Land Rover eccentricities, but they do make one for Range Rovers which is claimed to boost output by a claimed 19 bhp and 30 ft-lb of torque (figures for the 4.0SE).
 

Classic Options
East Coast Rover offers a plug-in upgraded ECU chip by Tornado Systems for the 14CUX EFI ECU family for $475. They also offer, for $675, a 14CUX chip for people who replace their 3.9 block with a 4.2 or 4.6.

For those willing to experiment with chips that are not specialized for Rover V8s, there are also other more generic options. When Dave Brown  was upgrading his Classic engine from 3.5 to 4.6 liters, he found  several brands of aftermarket engine management computers, including Haltech, Motec, Electromotive, Fel-ro, Accel, and SDS, ranging from $1000 to over $5000 US. They vary from fuel management only to complete engine management with control of ignition timing, spark duration, etc. Dave chose the Haltech F9a, a fuel-only system including an O2 sensor control ($1200 US complete with sensors, ECU, and wiring harness). The Haltech software is DOS based, and an RS232 cable simply plugs into your PC, allowing you to monitor and change the engine settings (base idle speed, fuel injector settings, cold idle temperature and RPM, O2 sensor control, etc). The other end of the cable is a standard RJ phone plug. Dave installed the Haltech system himself (see details and photos in the Haltech F9a Installation Page), but had a dyno-tune shop with Haltech experience set up the fuel maps. "This is what REALLY brought the beast to life! Well worth the $370".  Ron Beckett also installed a Haltech ECU, putting his on the kick panel between the door and the remote bonnet release handle on his 86 RR. He has some pictures of his installation on the web. As an aside, Dave reports that the documentation for his F9a unit says that you can use it with a supercharger, if you add a 2 or 3 bar MAP sensor to cope with the higher manifold pressure.

 

Haltech F9a Installation Details (Classic)
Dave Brown was kind enough to supply details and photos, available here, of his Haltech F9a engine computer installation so others can benefit from his experience.

Richard Kersey replaced his engine management ECU with a Wolf 3D (current model now 4D he thinks). This installation does away with the air flow meter (a scourge according to Richard) and the engine can be tuned from inside the cab! Richard has had it for 4 years or so and since fitting it has been the most reliable ever. The web page for wolf is www.wolfems.com.au

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Engine Swaps/Upgrades using Rover V8 Engines

Many Rover owners might yearn for enough power to avoid being blown into the weeds by Honda Civics. The most direct solution is to swap in a bigger engine. Swapping in a larger capacity Rover V8 engine is by far the easiest approach, avoiding all the hassles of fitting an engine of another brand, such as a weight increase and the need for adapters and cutting holes to fit things. Most of the ancillary wiring, sensors, plumbing etc can be left as is. Rover V8s are now available in capacities up to 5.2 liters -- enough power for most purposes. RPI Engineering now advertises a 5.2 liter Rover V8 swap for the P38, with a 0-60 time under 7.5 seconds and a top speed of 140 mph. In the USA, the RPI engine range from 3.9 to 5.2 liters can be  supplied and installed by East Coast Rover of Warren, Maine, (207)594-8086, and the British Car Company of Corte Madera, California, (415)927-2995. Rovers North offers a 4.5 liter "Dakar" Rover V8 engine from JE Engineering in the UK. I recently (April 04) found a new source for Rover V8 upgrades -- Lund Engines. This is a UK firm that will build anything from stock to a full race version of your engine.

3.5/3.9 to P38 Engine Upgrades
The P38 engine design has a large number of detail improvements over the 3.5/3.9 version, including a bigger and better oil pump and larger oil passage ways for better oil flow, many local improvements (including stiffening) in the casting design, cross bolted main bearings, and reduced tendency to blow head gaskets. It also addresses the tendency for valve lifter sticking, excessive timing chain wear, and premature distributor drive/oil pump drive shafts and gear wear on the older engines. Nearly all the larger (4.9 and 5.2 liter etc) engines produced by the above aftermarket suppliers include all these improvements.

All 3.5/3.9 engines are prone to blowing head gaskets due to a poor head bolt pattern that put too much pressure in some places and not enough in others. The fix was in only using 10 bolts per head, omitting 4 of them. (For those replacing the head gasket on a 3.5 or 3.9. Land Rover has new composite gaskets that come with a new set of bolts, and a different torque spec). The P38 head design addresses these problems permanently.

When upgrading a 3.5 or 3.9 to the newer 4.0 or 4.6, you have a choice of keeping the old 3.5/3.9 timing cover with its multiple belt setup using the original oil pump, or upgrading to the new timing cover using a single serpentine belt and the newer design high volume P38 oil pump, (internal/external gear pump rather than 2 meshing external gears).

4.0 to 4.6 Liter Upgrades
The main difference between the 4.0 and 4.6 engines is the longer stroke of the 4.6. This entails different crankshaft, pistons and connecting rods. RPI Engineering  are working on an upgrade kit that will work out cheaper than a new short block engine for those already owning 4.0's who wish to upgrade to a 4.6. The expected cost of the kit will be about £650.00, including crank, bearings, pistons, rings & con rods etc.

 

A 3.5 to 4.6 Liter Swap
Dave Brown kindly supplied details and photos of his upgrade to a 4.6 block on his 87 RR, which can be seen at this link. (The original engine lost coolant and severely overheated -- a non functioning temperature gauge sensor gave no warning).

 

A 3.9 to 4.2 Liter Swap
Michael Slade swapped in a 4.2 after his 3.9, with 188K miles on it, shattered the timing gear near Teslin, Yukon Territories (a $1,000 flatbed ride from home). He considered a GM engine but decided to stay with a Rover mill since the tranny had recently been replaced (with a unit out of a Discovery with 50K miles), and he did not want to swap that too.

Michael sourced a 4.2 long block (with heads but no ignition, timing cover, oil pan, etc) from East Coast Rover for $1200 -- a running 40K mile unit that they pulled out of a LWB to install a 4.6 "stage III" that they sell.  The engine arrived tied to a palette, uncovered and a bit dirty, having been exposed to the weather. The #6 piston had a bit of rust.  Another $300 got it delivered to Shipman's shop where he balanced and blueprinted it, ported the heads, etc for $1500. He also put in a new power steering box, new hoses, fixed the steering donut which was cracked, and upgraded the timing chain and gear to a much stronger non-Rover American unit (Edelbrock?). A Crane ignition system was added for a smoother, more consistent spark pattern (the scope confirmed this was true, showing a dramatic difference comparing a stock to a Crane ignition). the 3.9 ECU chip was retained.

At the same time, Michael replaced the entire exhaust with a Northwest Rover Performance Inc  (NRP) Exhaust System. He did find it a tad throaty and loud, and his wife did complain about it on a drive to Utah. He is considering a rear muffler to quiet it down a bit.  "It does sound really cool though the way it is now. Just a bit loud".

After the combined engine and exhaust swaps, Michael noticed his RR has "a lot more power". After 15,000 miles on the new engine, he reports being very satisfied with the smoothness and power increase over the original 3.9. The vehicle has bags of power even with its big tires (265/75R16).

 

4.2 to  4.6 upgrade
Ron Beckett offers the following observations on this swap: "It's not a problem. You'll need a camshaft from a 3.9 as the 4.6 camshaft doesn't have skew gears for the distributor oil pump drive. You'll need a spacer for the crankshaft nose as the nose is longer (the 4.6 has the oil pump in the timing case driven by the crankshaft). Get an old front pulley and cut the nose off it. Machine it to length (I can't remember the length but I have done it). Alternatively, buy the spacer from an after-market supplier. In Australia, Graeme Cooper has them fairly cheaply. You'll have to use the 3.9 timing case for the oil pump and distributor mounting. You won't need the outer row of head bolts. Only early 4.6 blocks had provision for them (e.g.,, mine in my P38A)

"Oh, I forgot to add that you may need to correctly shim the flex plate on the torque converter. You should really read about that in the LR workshop manual. It depends upon the engine number."

BMW 4.4 V8 Engine Upgrades (Mk III Range Rover)
For the Mk III Range Rover, Special Vehicle Concepts has produced a 340 HP version of the 4.4 V8, and can sell the power boost conversion separately or as part of one of their customization packages including upgraded drivetrain, suspension, brakes, interior and exterior trim. Overfinch conversions are also now available. They stick to the BMW 4.4 V8 used in the stock vehicle but bore and stroke it to achieve a 5.0 litre displacement. This version is sold as the "580S" and cuts the 0-60mph time from 9 to 7.1 seconds.

Engine Swaps using GM and Ford Engines

Ford 5.0 V8 Swap:
Dave Brown investigated using a Ford 5.0 HO engine from a '90 Mustang, with 220 hp and 300 ft lbs of torque (roughly matching the specs of a 1999 & up 4.6 engine). An adapter kit was available from Sierra Motorsports. Another choice was rebuilding his 3.5 with a Buick 300 crank, boring and stroking it to around 278 cubic inches, but Dave had reservations about the major machining and adding a 35+ year old crank to the motor. He eventually opted for a Rover V8 swap using a 4.6 block (see details here).

 

GM V6 Swap:
John Cassidy installed a 4.3 liter Chevy V6 Vortec engine in his 1987 Range Rover; this mill is more compact and, with some minor modifications, produces significantly more power and torque (211 hp @ 4500 rpm and 327 lb ft @ 2000 rpm) than the 3.5 it replaced. Whereas a small block V8 weighs about 200 lbs more than the Rover V8, the V6 is only about 100 lbs more. However a lot of work was involved, and at last report the bugs were still being worked out.

 

GM V8 Swaps:
These are the most common swaps into Range Rovers. Dave Brown offers the following thoughts to those considering a Chevy 350 (or any non-Rover engine). You will need an adapter to mate the engine and trans, or if you replace with a GM engine AND trans combo, then you'll need an adapter between the trans and x-case. (See the Marks 4WD Adaptors and Advance Adapters web pages for info). If you go to a different  trans, you will want to consider the trans gear ratios.  The GM TH400 is a strong unit, but may not have the proper ratios to move your Rover. (It also has no OD).  The GM 700R (?) trans is reputed to have heat problems (which no doubt can be corrected at some expense), but has OD.  Then there's the matter of an engine management system (EFI computer).  Aftermarket are available at semi-reasonable costs.  Or maybe you can use a GM unit.  If your state/country allows carburetors then you have that much less to worry about.

You will also have to contend with the water hose locations relative to the radiator and heater box, fan clutch and shroud spacing, exhaust, AC hoses, power steering pump/box hoses, oil and temp gauges, (just add aftermarket units!) motor mounts, oil pan configuration (clears front axle), oil filter location, starter motor/flywheel contact and mounting, additional weight of the iron block and heads engine, etc.

Best bet would be to source a complete motor (fan-to-flywheel, oil-pan-to-plenum) with all ancillaries.  GM sells a "crate motor" that is complete like this  (Go for the high performance one!!!).  You may need to use a Blazer/Tahoe oil pan to get front differential clearance.  (Wrecking yard.)  Caution, different oil pan may require a different oil pump pickup tube.

Another consideration is the extra 200 lbs weight of a cast iron V8 compared with the Rover aluminum engine; however this could be ameliorated by using a Corvette aluminum V8. Four Wheeler magazine ran an article on a Corvette-engined RR sometime around 1993.

Overfinch in the UK used to perform these Corvette conversions professionally and sell the resulting vehicles with other upgrades including suspension modifications as a package. During the production life of the P38 models, Overfinch also converted these with the same 5.7 litre Corvette engine, sold as the "570 HSE". 

One owner, John, feels the transmission problems inherent in these conversions should be emphasized. He had an Overfinch conversion of a classic with a 5.7 Corvette engine. "For the cost you would assume it had been done as well as possible and Overfinch had a lot of experience but by the time I sold the car at approx 65000 miles it had got through 6 transmissions!! When I looked through its early history it had originally had 700R box but after blowing 2 up in under 20k was fitted with beefed up stock ZF which it continued to chew up on a regular basis. Oddly the transfer case never gave any trouble. Although the car was very quick for a 4*4 the fact you couldn't rely on it to get you home made it a toy rather than a proper tool."

We do not want to scare potential converters off -- it's an interesting project, but don't go into it lightly.  Look at the Advanced Adapters web page, and Marks Adaptors, and seek experience from the UK or Australia, or some place with a lot of Rovers and Chevys. (Overfinch, in the UK, does these conversions commercially).

 

Gearing Changes
Enthusiasts of tall tires may need to consider a gearing change in order to preserve reasonable acceleration. The tire size cutoff point where a change of pinion gears is indicated is generally agreed to be somewhere in the range of 5-10% over stock. British Pacific recommends a gearing change to 4.1:1 for those seeking better acceleration even with stock tires.

Various gear sets are available for Range Rover differentials, ranging from the stock 3.54 upwards. Bill Davis from Great Basin Rovers recommends 4.1 to 1 as the practical upper limit for a direct swap, beyond which the smaller pinion gear is seriously weaker than stock.  He feels that if you insist on really low gears in the 4.7:1 range, you should plan on installing them in a 4 pinion style diff carrier (such as the diffs used on Range Rover traction control axles, or an ARB or Detroit), because most ring and pinion gear failures are  caused by the stock 2 pinion carrier flexing or cracking and letting the contact point of the gears shift out toward the ends of the gear teeth. Another suggestion would be to use 4.75 gears which have a different tooth count (8X38 vs 10X47) and are stronger, but a 4 pinion carrier should still be used.

For those interested in "granny low" gearing for rock crawling, older Range Rovers (pre 89) with the LT320 transfer case can be converted to a 30% lower low range gearset available from Great Basin Rovers. The kit contains a new intermediate gear, low gear and intermediate shaft that is pre-shimmed so installation is said to be quick and easy, with no major modifications required. High/Low range gear selection (via dog clutch) remains original, and high range gearing is unaffected. Great Basin Rovers also has this gear ratio available for the P38 models. For granny low gearing, Ron Beckett suggests also having a look at http://www.4wdworld.com.au/products/maxidrive/.

Shocks (P38)
David Currie agrees with me that the shocks on the P38 models are too stiff, giving a harsh ride over small bumps. I have seen this criticism in magazine reviews also. The difference is especially noticeable after the "magic carpet" ride the Classic gave over rough terrain. In 1997 the shocks were revalved slightly softer, but this was not enough to make much of a difference off road.

Few if any shock manufacturers specify shocks for the P38, one exception being Bilstein. The usual Bilstein shocks are known for giving a "firmer" (i.e. harsher) ride than stock, but David found that they makes a "Comfort" shock and wonders if anyone has tried these.  Richard Young (August 2006) spoke with Bilstein’s off road division on the subject of these phantom “Comfort” shocks which nobody else has been able to track down. He found they do make a shock with that designation, however, they do not make it for the Range Rovers.  Shane, in Bilstein's off-road division, said the Bilsteins that they set up for the P38 are already pretty soft by their standards, but could certainly be valved softer if desired.  The cost per shock is $65.00 to custom valve. This certainly helps clarify the mystery shocks. Bilstein’s contact number is (858) 386-5900. See the Shock Replacement page for details of Bilstein shock installation on a P38.

Ian Dugdale reports that Koni red or Special shocks (road, not sport) are a good compromise for the P38/P38; he reports they are valved similarly to the Bilsteins but are valved for comfort while incorporating a strong rebound which reduces sway. Allan Hogan has upgraded to adjustable Konis on his 4.6 (February 2007); details of his installation appear on the Koni Adjustable Shock install page.

Steering Stabilizer Upgrade (P38)
Ian McKiernan reports on another tip that has been the most satisfying upgrade for him recently, after replacing the wheels on his 4.0 with RR Mk III wheels (an operation described on the Wheels and Tires Page). "The 19” RR MK III wheels and the 18” “Hurricanes” for that matter would really throw back a lot of steering jounce when traveling over irregular road surfaces so I looked into an aftermarket steering stabilizer for the P38 Rovers and found nothing until I called Rancho (part # RS5406) the bolt on took a simple 10 minutes (exc. for the fact that I am a perfectionist and painted the shock gloss black and put a grey shock boot on it rather than cheesy white/red boot Rancho colors)".

 

Supercharging

Another way to boost power is to supercharge the engine. The best known supercharging kit for the Rover V8 is from Rimmer Engineering, using an Eaton blower. A supercharger is more desirable for a 4x4 than the more common turbocharger in that it increases power throughout the rpm range (rather than just at high speed) and does not cause the traditional turbo "lag" or "surge". One source for Range Rover supercharging information is  http://www.charfire.com/ . I recently discovered that Special Vehicle Concepts offers supercharging kits for the P38 engine, which would also work on the 3.9 (Classic) but you should check with them for details. They can also do the whole job for you.

RPI Engineering warn against the supercharging approach, stating that it results in uneven distribution of air and fuel to the different cylinders if a supercharger of inadequate size is used. They once had a picture on their site showing the innards of a blown engine that was fed unevenly. Naturally, they recommend using one of their bored and/or stroked blocks instead if a power increase is desired. I do know that the supercharging approach was good enough for the official Range Rover SSE  model variant in 1997, a couple of hundred of which were produced, and sold through the official dealer network. These were produced by Special Vehicle Concepts (then Cameron Concepts). John Rogers bought what appeared to be one of these models used. He found the supercharger worked great. He initially experienced some pinging when it got hot outside (over 90 degrees) or on a grade (load) while towing. Going into boost in this condition, detonation started and power dropped off inversely proportional to the power setting (throttle). However all this turned out to be due to unrelated electrical problems; after changing his power cables (particularly the one from the alternator to the starter) everything worked perfectly, and there was no more pinging. The engine also threw the occasional Check Engine code, but cleaning the MAF sensor helped considerably. 

 

More Information

Our pages on
Common Range Rover Problems and Fixes (Classsic),
Chip Sets for Power and Economy Upgrades
Range Rover P38 Problems and Fixes and
Mk III Range Rover Common Problems and Fixes cover "how-tos" on many of the things that most often go wrong.
Repair Operation Details provides detailed "how to" on many repair operations.
Air Suspension Diagnosis and Repair covers the complete air suspension system.
RR Suspension Details and Mods and
Range Rover Tires cover upgrades to these items.
Customized and Upgraded Range Rovers from Special Vehicle Concepts
Maintenance Operation Details routine maintenance tasks.
Parts and Service Sources helps you find the parts you need.
Re-Chipping for better power and economy
Customizing Range Rovers (Overfinch and Special Vehicle Concepts) (power, interior & exterior upgrades)
Expedition Accessories,
Winch Mounts  and
Vehicle Recovery Equipment cover the addition of off-road equipment to your Range Rover.

Other sources of info:
Air Suspension Problems (Classic)
Advance Adapters
Atlantic British Coil spring conversion kits with electronic module to eliminate error messages
ATP Electronic Developments Ltd (Remanufactured EFI parts)
Chevy Vortec V6 Conversion for RR Classic by John Cassidy
East Coast Rover (Coil spring conversions, ECU upgrades, new & rebuilt engines)
GM Diesel V8 Conversion guide and information resource by Brian Cotton
Great Basin Rovers (Differential gearsets, granny low transfer case gears)
Marks 4WD Adaptors (Adaptors for GM V8 and Transmission swaps)
Motor Cars Ltd Black Dog Air Valve and Coil Spring Conversion Kits
Northwest Rover Performance Inc. (Exhaust Systems)
Overfinch Range Rovers with upgraded engine and performance packages
Performance Options for RR V8 Engines  (British Pacific Tech Tip)
Rear Axle Leaks (Rovers North Tech Tip)
Robison Service (Coil Spring Conversions)
Rovers North (4.5 Liter "Dakar" Rover V8 engines)
RPI Engineering (New and Rebuilt Rover V8 engines, 3.9 to 5.2 liters)
JE Engineering (Rover V8 performance upgrades, supercharged engines)
Shop Manuals available from www.books4cars.com
Special Vehicle Concepts Customization of Range Rovers incl power, interior & exterior upgrades
Spring Specs -- part nos & data for factory Land Rover springs (Four Wheeler web site).
Spring Specs -- More: from the Land Rover Club of Luxembourg
Spring Specs -- Old Man Emu from British Pacific Website
Superchips Inc. (Performance Upgrade Chips for 4.0SE)
Triumph Rover Spares (Engine Upgrades -- Australia)

 

 

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Page revised February 1, 2012