Standing on huge 20 inch alloy rims with low profile tyres and adorned with ‘Gale Force’ livery, the Twisted Performance Defender makes its presence felt even when standing still. Men who should have grown out of it were asking if they could take a look and the Yorkshire holiday traffic slowed to peer at it whenever it was parked by the side of the road.
There is more to the truck than the wheels and livery, as under the bonnet is a modified version of the newly installed 2.4-litre 4 cylinder Ford based engine.
By all accounts, tuning this new engine has been difficult. Bolt on additions have played their part, but the secret of making one of these go better lies in what has been done to the engine management system.

Modern fuel injected engines use three-dimensional mapping; that is, the amount of fuel allowed into the engine is varied according to differing engine revolutions, load and throttle position. If you look at a fuel map laid out on a computer screen, it looks much like a mountain range with peaks in the high load and high rev areas, and lowland areas where the revs and load are less.
If you break into the mapping you can increase the fuelling in critical load and rev areas and increase the amount of power available. You can also screw things up big time. The more modern the engine, the more advanced the management system is and the easier it is to get it very, very wrong. This is why it has taken months for the tuning companies like Twisted Performance to debut their tuning packages.
It’s not all about changing the fuelling parameters; to take advantage of a re-map some physical tuning has to be done. It’s no use pouring more fuel into an engine if the engine won’t burn it, as that would just result in a dirty exhaust and high fuel consumption. The only way that you can get an engine to burn more fuel properly is to give that extra diesel more air and thus oxygen to mix with it.
As a cylinder can only accommodate a certain amount of air when working at atmospheric pressure, you have to find some way of artificially increasing the amount of oxygen that finds its way in.
This can be done either by piling more air in using increased pressure (turbocharging or supercharging) or by making the air that is going in contain the maximum amount of oxygen possible.

The first option is already being exploited to almost its fullest extent as Land Rover engines are turbocharged and, although the boost can be (and is) increased slightly, there is only so far you can go before unreliability creeps in. Twisted Performance therefore looked at other areas to help things along.
A free-flowing air filter allows the turbo to gulp its fill and the burnt gasses passage to atmosphere is eased with an exhaust system that is as unrestrictive as possible.
This all helps, but the gains are limited. There still has to be more oxygen available to get the big power boost that comes from more fuel.

stuff it in
Luckily for the engine tuning fraternity, the laws of physics allow a ‘more oxygen in the same volume’ option.
All that needs to be done, is to cool the air being supplied by the turbocharger. As the incoming charge is cooled it becomes denser, and dense air contains more oxygen, hence we can inject more fuel and get more power.

In the same way as a big, efficient radiator is used to cool an engine, it can be done to the incoming air. The Twisted Performance vehicle does just this. Being fitted with a more-efficient-than-standard intercooler, which cools the air to below the temperature at which it enters the engine as standard, it allows additional fuel to be added for extra grunt.
Grunt describes the additional power from the TP modifications perfectly; if you put the Landy on a rolling road and measured the extra horsepower you wouldn’t find a huge difference. However if you measure where the horsepower now comes in the rev range and then translated it into a torque figure, you would be stunned at the gains that have been made.
Torque is a measurement of power factored against revs; the lower down the rev range that power is produced, the higher the torque.
The difference is in the order of 100Nm (in old fashioned imperial that’s around 75ft/lbs).

muscle car
On the road this difference in torque translated into being able to drive the Defender quite differently from the standard offering. Whereas sixth gear on the factory Defender is really only for motorways, the modified Defender can be hooked into top at any speed over 50mph and muscled through twists and turns without recourse to the ‘box – unless you are forced by other traffic to drop your speed or a big hill gets in the way.
There is also no doubt that the larger diameter wheels and low profile tyres improve the handling of the new Defender, making it more positive on the road and removing the squirrelling that the OE rubber seemed to cause.

If I have any criticism of the modified machine it is that the extra torque and power tends to amplify a couple of existing problems with the Defender. When you lift off the throttle, the motor tends to keep pulling for a fraction and when putting your foot down again there is some throttle lag. This is mostly down to the Variable Vane Turbo and many drivers won’t find it a problem, as they tend to adapt their driving styles very quickly to account for it. I probably didn’t use it for long enough to adapt, but still enjoyed the modified Defender immensely