Thread: 3.9 performance

These numbers may help as guide for a 3.9 original around 200K in good nick ie a quick and dirty check as follows....

....Uses less 3/4 litre oil per 5K and rocker gear a tan colour (if so timing/valve gear should be OK), compression even and close to 155 lb (if not more lb courtesy of some carbon), fuel pump/injectors/sensors all OK, throttle/upper engine clean and plugs indicate AFR/timing OK. I would be dissapointed if that package is not producing 70 KW (power) / 3000 N (tractive effort @ say 50 - 80 klm/hr in 2nd gear WOT) at the wheels.

1. Simply increasing initial advance as Mike suggests should produce a free 5%+ or say 5KW.

2. With a standard 14CUX fuel map a remapped distributer should generate another 5%+ more power and torque in the right place. Say 80 KW max. You can do this using a Jaycar/Silicon Chip Electronic conversion or respring your existing distributer (inc dyno time) or buy one already done like a Scorcher....say around $600.

3. Remapped fuel map (that changes injector duty cycle) add another 5%+ or say 85 KW total and which timing can be customised to. That will cost around $700.00

Alternatively do timing and fuel together (1, 2 & 3) with piggyback such as Haltech or Unichip (albeit piggyback not ideal for fuel as it won't change duty cycle) for say no more than $1500 inc dyno time.

After that your probably only fiddling at the edges with a 3.9 in good nick and upping capacity is the only cure.

Landrover Melbourne have some 4.6 short motors still in stock, I got quoted 3200 + gst. Use your existing heads and get them recond to suit, a cheaper option perhaps.