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4WD Engine Conversions.

There is a whole industry, and hobby, in converting four-wheel drives - installing different engines and transmissions in particular. Modified suspension, bodywork and brakes are also installed, but more of that elsewhere.

[Chevy into MK Patrol, jpg, 11K]
A Chevy, with adaptor, about to be dropped
into a Nissan MK Patrol.

Manufacturers go to a great deal of trouble to find the best compromise in terms of performance, tractability and reliability for their vehicles. 4WD engines have to be flexible and capable of running at extreme angles. Car-type engines may be great on the highway but not so good off it. Still, 4x4 owners are inveterate tinkerers and always ready to try to do better than the manufacturer, but before taking your pride and joy to bits, remember that licensing authorities will require it to pass appropriate safety and pollution standards when you have put it back together; check first. Some insurance companies are also suspicious of anything non-standard.

When the vehicle has done 100,000+ miles and the engine is getting tired, it may be as cheap to install a non-original motor as to recondition the old one. The chance is often taken to install a more powerful motor that is locally available. That may require other components to be uprated and suddenly it is not so cheap any more, but it will put new zing into the old truck.

An engine adaptor kit will include either a new clutch bell-housing or an engine to bell-housing adaptor. Engine mounts will match the motor to the chassis. A longer motor may necessitate moving the radiator forwards which may also require surgery to the chassis or front bodywork. Car-type engines often have a rather low mounted water-pump and it may be necessary to change the fan shroud or to install an electric fan. 4WD radiators are usually heavy duty and may serve a larger engine, but a clean-out is a good idea. Inlet and outlet pipes might have to be moved to suit the new motor. The front diff' might strike the new sump unless the latter is modified. Baffles may be needed in the sump to maintain oil pickup at extreme angles. Prop-shaft lengths will change if the transfer-case is moved fore or aft. Gearbox linkages sometimes need modification. Uprated brakes and stronger transmission may be required if there is a large increase in power.

Australian Land-Rovers frequently have Holden (GM) 6-cyl motors installed. Ford V6 (2.8L or 3.0L) transplants are popular in Europe. I even recall seeing an ad' several years ago for a BMW conversion for a Land-Rover; at the time it seemed overly exotic but maybe the kit manufacturer was prescient (BMW bought Rover in 1994). 3.5L V8 Rover car and Range Rover engines, and 4.4L V8 Leyland P76 engines have also been fitted to series 1 to 3 Land-Rovers, but given that they have twice the power of a standard unit, a light right foot, or a stronger transmission, is advised, especially in a long wheel-base model. The original 2.25L 4-cyl engines of series 2 and 3 Land-Rovers are good sluggers but are not the greatest highway cruisers. However, there is not a lot of benefit from a big-engine transplant unless the overall gear-ratio is also raised. Fortunately there are several options: A Fairey (now Superwinch) overdrive can be fitted. Taller diff's can be fitted instead of the original 4.7:1, e.g. 4.1:1 from Rover cars or 3.54:1 from the Range Rover and later Land-Rovers. A 5-speed truck gearbox with overdrive can be fitted, such as the Nissan unit made popular by Mark's 4WD Adaptors. When it comes to stopping, short wheel-base brakes can be uprated to long wheel-base brakes and power-assistance added to the muscle-driven variety.

Chevy V8s and Holden V8s (4.2L or 5.0L) are the most popular transplants into Toyota Land-Cruisers and Nissan Patrols. The Chevy has a rear-mounted distributor and Mark's make an adaptor kit to move the engine 4 inches forwards to clear the firewall, while leaving the transmission in its original position. (Licensing authorities do not care for tampering with the firewall.) A short extension-shaft mates the Toyota gearbox to the Chev' clutch. It would be prudent to consider disc-brakes, at least for long wheel-base vehicles, to help with stopping. Incidentally, there is a question over the strength of the early 1970's Land-Cruiser transfer-case with the small intermediate shaft.

Other conversions include Chevy V6s and Holden 3.8L V6s going into Nissan Navaras and Pathfinders. The Holden V6 is a neat fit in a Toyota Hilux. Corolla engines are popular replacements in older Suzuki 4WDs. I am told that:

Swapping motors in Suzukis is not difficult as the gearbox and transfer-case are separate and connected by a short tail-shaft. To do a motor swap, you use the gearbox from your chosen motor and have a tail-shaft made to suit. The most difficult part, ie. matching motors, gearboxes and clutches, is avoided.

Those seeking better fuel economy and a safer, if smellier, fuel can install a diesel motor. An easy option is to use a diesel from the vehicle's own manufacturer. Alternatively, Iveco, Perkins and Isuzu diesels, often turbo-charged, are popular replacements in European Land-Rovers. The American connection offers Oldsmobile 5.7L V8 and Chevy 6.2L V8 naturally-aspirated diesels for larger 4WDs; they are surprisingly compact (if wide) and have lots of torque but you might want to raise the overall gearing.

The big diesels have even been squeezed into elderly Range Rovers, a vehicle where it is particularly easy to raise the hi-ratio gearing of the LT95 (4 speed) transmission by changing two cogs. Another option is to use the Isuzu 4BD1 3.9L 4-cyl diesel as factory-fitted to many Australian Land-Rovers of the 1980's. They say that it is a bit crude but goes forever.

Another adaptor is needed when it comes to linking a non-4WD gearbox to a 4WD transfer-case. The gearbox drive is carried into the transfer-case by an extension shaft. This is splined to the original output shaft at the front end and runs on the usual transfer-case bearing at the rear end. Nissan and Toyota light-truck gearboxes are popular as they are strong, compact and have an overdrive 5th speed (higher than 1:1). Being originally column-shift gearboxes, some early conversions had a reversed gate but recent conversions have the conventional shift pattern.

Automatic-transmission conversions are done in a similar way, although most vehicle manufacturers have now woken up and are offering their own automatic gearboxes in their 4x4s.

Finally, if you are buying a second-hand 4WD that has been converted, make sure that it is registered and approved in its current guise.
- 4wd.sofcom.com/4WD.html

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