Mitsubishi Colt Rodeo / Pioneer 2.8 TDi
Performance Tuning | More Power | Turbo Diesel Specialists

Steve's Auto Clinic has breathed its magic on a Mitsubishi Colt Rodeo / Pioneer 2.8 turbodiesel -- not to increase performance dramatically, but to make the vehicle more drivable and frugal. We put it to the test.

Diesel has come a long way in the last couple of years, not only in terms of the fuel used, but also in terms of engine technology. But like anything mass-produced, there's always room for improvement, and the Colt Rodeo / Pioneer 2,8 turbodiesel engine is a case in point. In standard form it is considered one of the best performers of its genre, and on paper it outguns the Isuzu KB and the Toyota Hilux, thanks in no small measure to the fitment of an intercooler, which cools the intake charge before it enters the engine. Experts will tell you that for every four degrees that the intake charge temperature is reduced, you'll see about one per cent more power, so it's surprising that air to air intercoolers aren't more common as standard fitment, especially on the highveld. Even an intercooled turbodiesel can be improved on, but as with any conversion, reliability can suffer if a holistic approach isn't taken.

Steve's Auto Clinic (SAC) believes it can guarantee the motorist a trouble-free tuning option.The key to unleashing power from the Colt 2,8 engine lies in the cylinder head, and SAC's research showed that airflow was being restricted on the inlet side, necessitating some changes to the shape of the inlet ports.With airflow improved, the camshaft was then re-profiled, a little extra lift and more duration on the inlet valves allowing the engine to breathe at its optimum. Though noise levels appear to be unchanged, the exhaust has also been revised with a low-pressure free-flow system used in place of the standard one. Finally, the injector pump settings are optimised because the air/fuel ratio supplied to a diesel engine is critical for its power, fuel consumption, and emissions.

The dynamometer report supplied by SAC makes interesting reading, with kW at the wheels moving from 68,7 kW to 85,7 -- an improvement of almost 25%. The peak moves up to 4 200 r/min from the 4 000 r/min at which Mitsubishi's data says a factory-spec vehicle reaches peak power.Torque reaches its maximum at 2 500 r/min -- as before -- but the total value goes up by 17,8 %, giving the SAC Pioneer the juiciest mid-range you'll find without consulting a steam locomotive buyer's guide.

It's the single most impressive aspect of the vehicle, and overtaking is an absolute cinch as a result.So where does the holistic bit come in, you might ask.Well, despite the extra power and torque (which by improving combustion efficiency contributes to a claimed reduction in fuel consumption of around 21%), the test vehicle was also fitted with a locally developed and manufactured exhaust gas temperature (EGT) gauge. This is fitted unobtrusively above the steering column where the small liquid crystal display can be read with relative ease. The temperature of exhaust gases close to the cylinder head is a critical factor for the long-term health of a turbodiesel engine, and under high loads the spent gases can reach a scorching 900 degrees Celsius.

In its standard form, that's exactly the kind of temperature that Steve Fischer says he saw when he drove this vehicle -- his personal transport -- at full load. However, with the reworked head, camshaft and exhaust, the EGTs never went beyond 720 degrees, even when we drove flat out for a sustained period or accelerated hard through the gears. Clearly, the exhaust gas temperature gauge has enabled SAC to develop the Pioneer to a level where outlet temperatures are well under control even in extreme driving conditions.

So while it would seem superfluous to fit one to a similarly modified Colt, SAC sees a market for other turbodiesels, especially standard vehicles that are used for towing, where the exhaust gas temperature could rapidly reach danger point without the driver being aware of it. While one hard run won't cause a failure, it is repeated visits to the danger zone that eventually result in a breakdown. The EGT gauge can warn the driver visually and then audibly when the threshold is being approached, and the instrument is also capable of monitoring turbo boost, and fuel efficiency.  The exhaust gas temperature (EGT) gauge is located on the steering column and warns the driver visually and then audibly when the threshold is being approached. The instrument is also capable of monitoring turbo boost, and fuel efficiency. SAC charges R2 650, fitted, in a process that takes less than an hour.

In both the suburban and open road environment, the modified Pioneer feels totally satisfying. The powerband is wide enough not to irritate the driver in stop-start traffic, while the speed at which the motor gets up onto the torque plateau, and the relatively gradual drop at the other end of the rev range, contribute to its easy-going nature.The Pioneer as a package remains an appealing one if you want a fairly affordable 4x2 double cab. (While the model has been dropped, its successor currently sells for R230,000). The dynamics of the firmly sprung chassis are keener than most, with steering response, in particular, giving it an agile feel. And with the standard diff lock, the same ride height and purposeful countenance of a Rodeo 4x4, it's already got the show to match the go provided by the conversion.

SAC is confident that, apart from adding thrust and reducing fuel consumption, the R7 995 conversion will prolong engine life.