Back to the Defender 90 Section

1997 NAS Defender 90 Soft Top
4.6 Pursuit V8 Upgrade

This 1997 NAS Defender 90 Soft Top has come to us from New Jersey for a new round of upgrades. We did some work on this 90 some time ago (go here for that work) and now it is back for a stronger power plant to cure the sluggishness of the stock 4.0 engine set up. On the dyno the 90 pulls about 132 HP and an average 171 foot pounds of torque. So if you ever wondered why it felt like your foot was always in the throttle of your '97 D90 all the time, now you know why... because you are only putting 132HP to the pavement. The automatic gearbox robs a ton of power from the motor. Its time for something much better to make this D90 with the automatic work more correctly. So the first step in upgrading this 90 is to go over it and get with the customer to see what they do and do not want done, then get to work getting that 4.0 lump out of the 90.

So out comes the stock 4.0 and the parts we need from it are stripped down, cleaned up and made ready for the new 4.6. Above you can see the old 4.0 long block out and stripped down.

To replace the old engine we will be installing this new Pursuit 4.6. Its a complete, new, modified assembly so there are no worries about the customers old cylinder heads or other worn/ about to snap and damage the new parts.

The Pursuit 4.6 differs due to the increased air flow that it has. The intake and the heads are fully ported for better air in and out. As you know the more air you can move the more power you can create. The image above shows the larger exhaust outlets in the Pursuit heads.

The intake is also matched to the heads. The air intakes are shorter and of larger diameter to allow for more air flow. The entire intake has larger runners and everything is gasket matched for maximum air flow.

Here you can see the stock 4.0 intake (right) in direct comparison to the Pursuit 4.6 (left). Its a world of difference and one you can feel when driving the 90 by not having to put your foot to the floor or into overdrive all the time. In our opinion all NAS 1997 D90s should have come from the factory with the stock 4.6 at least. You'll also notice above that we have installed some upgraded injectors and we will raise the fuel pressure so that they will atomize correctly in the Rover V8s EFI system.

Another trick on this Rover to increase air flow is the addition of Jet-Hot coated exhaust manifolds, see above. Short of doing custom headers this set up is a great way to gain some performance, reduce the under hood temps and accelerate the exhaust gases (all items that an NAS D90 really needs).

To cap off the air in/ air out theme we have finished up the exhaust with a ROX 304 stainless steel performance exhaust system with Random Technology cats. This will give the most performance possible and keep everything above board with the EPA as well. The 304 stainless system also won't rust out so it will last season after season on this Defender.

A little more work and the new Pursuit 4.6 will be ready to be installed into the D90 and then hooked up to all the systems. Once the motor is installed we will replace both ECU chips with upgraded units from Tornado Systems and then get ready to fire up the new engine.

Here you can see the new Pursuit 4.6 installed into the 90s engine bay. The fit and finish is correct because this is based on a Rover engine, and everything can be serviced by your local dealer if need be. Unlike other types of engine installs the installation of a Pursuit 4.6 actually increases the value of your Defender and keeps everything easy to service and repair if things pop up down the road.

Along with the engine upgrade the customer wanted a few other small things done. Items like... wing top guards...

Sill and rear quarter guards...

and a rear step plate. We also removed some surface rust from the rear cross-member and epoxy primed and painted it for a much fresher look to the rear of the Defender.

Here you can see the completed project ready to head back to NJ. Its now a much better running and driving Defender and with a lot more torque, and basically no MPG decrease thanks to the new Pursuit 4.6 and upgraded EFI system. Now the customer will have a lot more fun while behind the wheel of this 1997 NAS Defender 90.

If you have needs for your Defender, from routine service to wild modifications, contact ECR. We'll be happy to help make your Defender everything you want it to be.

Contact info