Frequently Asked Questions

Through the action of compressing the air, a turbocharger increases the air temperature considerably. Exit temperatures of 80°C are common. Every engine performs better with cold air to the intake so it becomes more dense and there is more air available for each power stroke.

An intercooler, also known as an aftercooler, cools the air post turbo prior to the inlet manifold.

Our preferred intercooler is an air to air front mount of as large a size that can be fitted. Sometimes there are practical problems, such as not enough room, large spotlights or winches, that mean another option needs to be found.

In these cases, a top mount air to air or a water to air can be used.

If a top mount air to air is selected, it is important a flange is constructed to force the air from the bonnet scoop through the intercooler.

Intercooler kits are available from PDI Performance Diesel Intercoolers, HPD and Cross Country 4×4. Alternatively, components can be sourced from eBay and your own intercooler constructed.

We recommend at least 65mm tubing and up to 75mm as space permits.

You should not be too concerned with “lag” as the GTurbo spools up so fast that the volume of air inside the intercooler and piping is very quickly brought up to pressure.

All pipes and hoses in an intercooler system MUST have adequate lumps on their ends to ensure hoses to not blow off under the heat and pressure. At least 6 lumps of 2mm high must be welded in place close to the end. All clamps should be retightened after two weeks or 1000km of running.

If an intercooler hose blows off under pressure, typically in a full power situation, it will result in the turbocharger spinning up to a much higher speed than it was designed for and can lead to turbo failure.

We have many customers who want to add a GTurbo to their engine at the same time as rebuilding it. We know the factory head gasket is solid and reliable with the higher boost provided by the GTurbo. Due to the variability of aftermarket head gaskets, and the difficulty of obtaining factory replacement head gaskets, we recommend a MLS, multilayer steel gasket be fitted during the rebuild.   After the rebuild, we recommend the fuel pump is set as standard and no fuel adjustment be made for the run in period.

The short answer is no, with the proviso that the engine is in good condition prior to performance being increased. This means no unusual noises, smoke, hard starting or worn components.

Let’s explain.

A major performance related issue that affects diesel engines is too much heat. This is why a common gauge installed by 4WD enthusiasts is an EGT, or Exhaust Gas Temperature, gauge.

A simplistic explanation of too high EGT is that there is too much fuel being injected into the motor and not being completely consumed by the combustion process. This excess fuel creates high exhaust gas temperatures, which should be kept below 700°C with a probe pre turbo, or 550°C with a probe just post turbo.

The fuelling levels are not only controlled by the drivers right foot, but by the settings made in the injection pump during it’s setup and any subsequent tuning. Correct tuning does ensure that the EGT levels are maintained within a safe range. This is done by the use of an Air Fuel Ratio probe.

Some people are worried about boost pressures too. However in a performance tuning environment, boost is your friend. Boost pressure represents a mass of air that is being forced into the combustion chamber. The more air in the combustion chamber, the more fuel can be added to make more power. Diesel engines are extraordinary in this way.

The trick is to get the right air fuel ratio, and the engine remains happy. Given a GTurbo is engineered to provide a greater mass of air than the injection pump can provide, achieving correct air fuel ratios whilst increasing performance is relatively easy. Performance is achieved with no smoke, excellent AFR’s and safe EGT. We will have it no other way.  You are unlikely to find another product that can achieve all these levels and still provide the exceptional performance improvements our customers rave about.

Once your vehicle is correctly tuned with it’s GTurbo, in particular if you have fitted a quality well sized intercooler, you will find your engine oil stays cleaner because there is less residual soot in the combustion process. Fuel economy does not change dramatically, sometime it even improves, all due to the greater efficiency of the engine.

All these factors augur well for a long engine life.

Some people also are, rightfully, concerned about the affect of too high boost on their standard Toyota turbo. The waste-gated CT26 turbo on the 6 cyl engines DO eventually break at much above 14psi

However the GTurbo is totally reengineered and balanced to effectively and safely run the boost we specify for long long life.


We offer two main specifications of turbochargers the 4 and 6 cylinder engines.

The Grunter and the Bad Boy.

Technically there is a 9% difference in the specification of each.

What matters to you as the driver is how it drives. The Grunter spec is great for low down torque, for towing and pulling hard through heavy beach sand where you don’t want to have to use lots of revs before you get any power. You’re getting good boost at 1600rpm and maximum boost by 2000rpm.

They typically perform in the 18 – 26 psi range and really transform the driving experience. Driving a manual gearbox, you no longer need to worry about losing boost on gear changes – it’s just always there ready to keep pulling.

For engines with a higher performance capacity, such as the 1HDT, 1HDFT, the Grunter Extreme is available. A billet wheel upgrade is available that maintains the low boost, but due to its superior design, strength and manufacturing accuracy, will provide high boost right through the rev range to similar levels as the Bad Boy

The Bad Boy range is for drivers who are willing to compromise a little of the lower boost response in order to gain more power for high speed performance. In real driving this compromise is minimal as the boost comes on strong well before 2000 rpm and climbs to much higher levels than are available with the Grunter range – 26 to 35 psi – with the consequential increase in performance.


One upgrade for turbochargers is to install a larger compressor wheel, and lathe out the front cover to accommodate the larger size. Yes, this makes a performance difference.

To say the GTurbo is ‘high flowed’ is very simplistic and not a phrase we use.

All GTurbo’s are reengineered from the back to the front.

Correct sizing of the exhaust impellor or turbine affects turbo performance. A small turbine will be easy to spin at low engine speed, but will spin too fast as high speed. A larger wheel will not start to spin to an efficient speed until the engine speed it too high and the engine becomes a ‘horsepower hero’ with plenty of power at top speed, but nothing down low in the normal driving range.   The GTurbo’s are sized to match the performance characteristics of each engine.

The shaft is beefed up to handle the higher load, the internal bearings have been rebuilt for long life. The thrust bearing behind the front compressor wheel is a full 360°, as opposed to the 270° of standard turbochargers.

And finally the compressor wheel at the front, the component that pumps the air to the engine, has been completely reengineered to not only be very quiet, and strong, but to maintain a solid ‘grip’ on the air at high speed and maintain exceptional efficiency across the whole rev range. This ability to keep pumping and not cavitating and creating heat is a stand out difference for the GTurbo.

Not only are all components reengineered for maximum performance and efficiency, the final assembly balance that makes so much difference to the longevitiy and performance of the turbocharger is critical. Our standards are extremely high, and we are not satisfied until we can achieve figures measured in the thousandth of a gram, at least ten times better than commercial turbo charger manufacturers and factory units.   We use the best European turbocharger balancing equipment available and are very proud of our results.

In order to provide as much of a factory appearance for our customers vehicles, all our turbochargers are OEM replacement on the flanges that bolt onto the exhaust manifold and exhaust pipe.

Some vehicles inbuilt computer provides a readout of distance to empty and fuel consumption.

If you fit a chip or piggyback computer to a vehicle such as this, the readouts will be incorrect – no matter which module you install.

The reason is that the OEM computer calculates these figures from the injected volumes, not a fuel flow meter in the fuel pipe. Given the injected volumes are quite modified from standard with the addition of a chip, and this is done between the OEM computer and the engine control systems, the OEM computer has no idea of the real fuel use.

For the majority of installations a 3” exhaust pipe is very satisfactory. When ordering a turbo, request a ‘Turbo back” installation, not a ‘dump pipe back’ installation. The dump pipe is a short section of cast iron that joins the turbocharger to the exhaust pipe. There is nothing particularly wrong with the design of any of the Toyota dump pipes, but they do not match up well to a 3” exhaust pipe. We would recommend Manta Exhausts or Mercury Mufflers for this.

For extreme performance, in particular the 1VD-FTV V8, a 3.5” or 4” exhaust is beneficial. Limitations are generally related to fitting the larger sizes in around the bodywork and chassis. We would recommend Redback Exhausts for this.

We measure torque in Newton Metres – Nm and at the crank.

We measure power at the wheels in Kilowatts.

1 horsepower = 0.75 kilowatts

1 kilowatt = 1.34 horsepower

Other frequently used expressions are:

  • Holy moly
  • What tha
  • Geeeeezussss

And accompanied by wide grins, and youthful antics from gentlemen well past a certain age.

And their passengers:

They often don’t say much. Just lots of blinking of their eyes and muttering under their breath, before they ask for the GTurbo contact details.

If you like, you express it in kilowatts, newton metres or horsepower. At GTurbo, we thoroughly enjoy the new driving experience and seeing our customers smiles.


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