I have a GU petrol 4.5 L Patrol. It weighs 3.8 t fully loaded with loaded, water, fuel, supplies, spares & passengers - a beast!
I have been considering how to lift the performance and /or improve the economy. I have reasonable records of fuel economy in a range of conditions.
I have investigated Unichip, which appear to be the only engine management system available, and consulted the Patrol on-line
forum - very little experiences/feedback/opinions are found.
So I went to the S.A. Unichip distributor, Morpowa, at Modbury.
On the dyno the standard power was 73 Kw at the rear wheels, with faultless air: fuel ratios. The boys suggested that in these circumstances an ECU style chip would not be expected to improve matters much if at all, and that a decent tune may be worthwhile.
For $ 198 they gave me another 10 Kw of power by advancing the timing 7 degrees. There are some other side issues such as pinging when such an adjustment is made, so after some testing, it was backed off to 6 degrees advance. The air: fuel ratios improved very marginally at that new setting.
Their other advice was to do with fuel. They recommended using 98 octane (I have only ever used 91 octane - regular unleaded). For an extra 10 cents a litre, or $ 19.00 per fill, this may be a much cheaper alternative to $ 1,600 plus for a Unichip. I do approx 20,000 km per annum in this vehicle, so this would cost $ 400 per annum. They suggest improved power and economy benefits. Early indications support this - the throttle is not open as far to drive at the same level.
When travelling in remote areas (half my driving done there, the other half getting there & back on the black top)) and 98 or 95 octane is not available, they have suggested adding an octane booster. The label on these octane boosters claims an increase of 6 or 7 octane levels, and a bottle to do a complete fill costs $ 11 - not so very different to filling up at the bowser with 98 octane. They have also suggested that if I wish to remain using 91 octane, but reckon on needing a bit more grunt - for example a heavy 4 x 4 session in deep sand - that I use some octane booster.
As it is almost impossible to replicate driving conditions, or to have a control in any comparisons of fuel economy and power, I am aware that any comparisons are going to be relatively subjective.
So as I have a 6,000 km trip on bitumen, station tracks and cross country coming up - in the Red Centre - I will be keen to observe the results of the tuning and different fuel supply.
Cheers for now.