Turbo and Intercooler

New Turbo

March 2011

Installed upgraded CT26 turbo, bolt on, supplied by my mate Graeme from GTurbo fame. Spools up earlier and on a dyno it will pull 450nm at 1700rpm - 440nm @1600rpm and EGT's only around 600°C. Awesome really!!  It also puts out 67kw at the wheels at 1600rpm, when the standard setup puts out the same kw at 3500rpm. 

What this new turbo does, is boost up lower and provide far more air at all speeds. This makes the engine burn all the fuel available to it and there is NO smoke under power on a dyno run. 

It pulls much better than before, though I'm trying to keep revs below 2200rpm for efficiency reasons. 

When running on Veggie oil the EGT ran 50°C hotter and had a measured 10% less power than diesel. 

 GTurbo Facebook link

GTurbo Website


May 2011

This was a big project, made more complex by me replacing the fenders at the same time. They had been accident damaged and the repairs started rusting out. 


I swapped them for a pair of HJ60 round headlight fenders in good condition.


The intercooler was purchased online from Just Jap and is 600x300x76mm with 2.5" outlets.

Silicone Joiners and clamps were purchased from Pro Boost Racing via ebay.

2m of straight 304 Stainless Steel 2.5" tubing, 63mm, and 12 90° bends were purchased at close to cost price through a handy contact. 

A flange was laser cut from a sample gasket by Action Laser Cut

On test mounting, I knew this was going to be a tight fit.


Left side


Right side


Obvious problems on the front panel was the mountings for the headlights. This car is the four headlight model. And also the bottom tray underneath the radiator that holds the indicators was going to need to be trimmed. 

A hole was cut that missed the radiator mount on the engine bay side. I drilled a number of holes with a 5mm bit and then cleaned up the edges with a die grinder. 

The routing of the stainless was fiddly and difficult as a first time job. I tacked the pipes using my inverter welder at 50A and special stainless welding rods. A friend then used his TIG to finish them off very nicely. 

intercooler pipes

tig weld

The hot side of the piping leaves the turbo and goes into a U bend forwards to descend down at the back of the alternator. Then it goes forward with an S bend through the hold next to the radiator. It's fairly simple and straight forward. To improve on this routing, the compressor cover of the turbo would need to be spun around and pointed down instead of up. If this is possible, I don't know. I suspect the only problem is the mounting of the waste gate, so it may be feasible. 




On the cold side, I was faced with how to route the piping around my veggie valving and hoses, plus the power steering pump and hoses. The solution was to run the piping along the motor and turn it down in between the radiator hose and radiator cowling. From there it goes through a series of small radius bends to clear the battery tray, and the inner fender, and through the hole next to the radiator. 

Some of these pipes needed to be reworked once I reassembled all the gear as I misjudged where for example the battery tray was going to sit and the piping needed to be 'eased' using a cut and a silicon joiner to create the right flex.

All the piping had tags of weld on the ends to stop the silicone sliding off. The cold side is covered in insulated tubing to keep the cold in. Unfortunately this hides the nice shiny stainless tubing.  :-(

The end result.

After the first outing the hot side was too hot to touch and the cold side was little more than ambient temperature - about 20°C

After a long run up a hill, the hot side measured 66°C at the intake of the intercooler, and the outlet was 25°C. Given the shiny nature of the intercooler, measuring the temps with an infrared was difficult. I placed some black tape to get a better reading, but a data logger would give a better reading and show graph-able readings. 

Radiator coolant temperatures were not apparently affected by the IC across the front of it; the cool ambient temperature would have assisted this - it's winter at the moment. 

EGT are lower than without the intercooler, perhaps 75°C lower in normal running - now 280°C pre turbo.

Performance remains excellent, with plenty of torque to spare at freeway speeds. Under full load at 80kmh up a long hill, EGT rose to 400°C, which is some 200°C less than without the intercooler on the same hill. 

Boost pressure lines

One of the things to do when installing a GTurbo on a 12ht, along with an intercooler is to reconfigure the pressure lines that support the boost adjuster and the boost compensator. The Boost adjuster is the thing you've installed to control the waste gate actuation. The Boost Compensator is the thing at the back of the Injection pump underneath the inlet manifold, hanging off the back of the governor. Standard installation has a pressure line going from the turbo cross over pipe to the boost compensator. As boost pressure rises, the IP opens up more and provides more fuel. 

Now you have a super fast boost build up, you want the pump to respond just as quickly. You also have a turbo that can handle much more boost than is best for a 12h-t (around 19psi).  If you have installed an intercooler, you have a bunch of air space in between the turbo and the inlet valves that has to compress under boost - called lag. 

To compensate for this lag, and take advantage of your GTurbo, connect the pressure outlet at the turbo directly to the boost compensator. So when boost rises, the IP can respond instantly. And to manage the boost pressure, hook up your boost adjuster to an outlet right at the inlet manifold. This way the boost adjuster sees the 'real' pressure at the inlet valves at the same time the boost is there - thus compensating for any lag created by the intercooler. Click here for a PDF with a couple of diagrams to show what I am talking about. 

Dec 2023 update:

This description might be a bit easier to follow. 

First the theory behind changing these lines. Note the standard setup is quite possibly just fine!   The concept is that you want the injection pump to be providing extra fuel in response to rising boost as quickly as possible so there is less lag. 

Please rest assured the GTurbo spools up pretty fast so you don't get much sense of lag once your revs are in a good range. However, especially if you have an intercooler, and why anyone would not want a good front mount is beyond me. PDI Intercoolers make a great kit for the HJ61. No one else bothers to support these old trucks. 

There are four components you need to identify. 

1. A pressure outlet at your engine intake manifold, or close to it. The standard cross over pipes have an outlet on the crossover between the turbo and the inlet manifold. The PDI kit has an outlet close the shut off butterfly. This will 'see' boost pressure at the manifold. 

2. The inlet for the boost compensator at the back of the governor at the back of the injection pump. There is a shaped plate with a rubber hose going to it now. There is a large adjustment nut and lock on this plate. Behind this plate is a rubber diaphragm. When air pressure is applied to the diaphragm via the rubber tube, it pushes a rod which activates more fuel from the injection pump. 

3. On the turbo snail or compressor housing, is an outlet for a rubber hose. This will provide the air pressure you need to activate the boost compensator.  

4. The waste gate actuator. There is a rubber hose attached to it by the good folk at GTurbo, and it goes to the outlet on the compressor housing. You need to remove this hose. The waste gate actuator responds to air pressure to move a rod that opens the waste gate. 

Is it getting clearer?  You have two sources of air pressure, #1 and #3.  You have two diaphragms actuated by air pressure. #2 and #4

A)  You need to run a rubber/silicone hose from #1 to #4

B)  You need to run a rubber/silicone hose from #3 to #2

The impact of step A is that the waste gate will only see boost at the engine intake, not another pressure that might or not be accurate given the reasonable volume of air between the turbo outlet, the intercooler and the piping. 

The impact of Step B is that the injection pump will deliver more fuel to compensate for the rising boost levels, as quickly as possible, without the impediment of the volume of air between the turbo outlet, the intercooler and the piping/ducting. 


The new fenders fitted came off a round headlight 60 series. All the research told me the fenders are the same. This is not quite true. The basic fender IS the same and was a direct fit. What was different, apart from the side turn indicators, was a mount for the  cover around the headlights. This was resolved with long screw to hold them in place. The side turn indicators were replaced with aftermarket LED lights that are very effective. In addition to the extra pair of turn indicators on the front winch tray, and polished up OEM lenses on the standard indicators, my intended direction change will be pretty obvious to anyone at the front or side!

Installation discussed on the IH8MUD forum and Perth 4x4.net forum. Click on links to go to discussion threads. 


April 2013.

The original GTurbo was whistling more than reasonable and Graeme had a new Grunter with my name on it, so I swapped them over. The sad state of the turbine wheel, and the whistle, was solely a result of me being slack and not ensuring air tight joins on the air intake. With the huge volume of air at high pressure on the outlet of the GTurbo, naturally the suction side is under as much pressure/suction. This is obvious in hindsight, but not something I considered enough in the first place.

Too many eager climbs of sand dunes had flooded fine sand into the engine bay resulted in sand being sucked into the intake, damaging the compressor wheel, covering the intercooler in sand and sadly, even a dusting in the inlet manifold….. eek. 

October 2016

Brian at Performance Diesel Intercoolers is developing a range of quality intercooler kits to suit several Landrcruisers. Check out what he has to offer.

IMG 0802

In addition to replacing the turbo with a new Grunter with Graeme's latest tweaks to give more power, boosting at lower revs and quietness, I cleaned out the intercooler of all the sand and oil that had misted in from the crankcase. I routed the crankcase vent into a catch can and then into the open air via the fender. Oil misting into the intercooler reduces it's efficiency, but does help in catching dust and sand - Of course, this should never happen in the first place!

I also installed a flex oil pressure line and rubber outlet to replace the steel lines that were hard to remove and refit. 

Soon after this installation, I went on a 2200km tour of the goldfields in a group of 7 other vehicles. The new turbo performed beautifully, giving me more power from lower revs. This surprised me, but not Graeme, who seems to be able to predict exactly what will happen for each installation. 

I thoroughly enjoyed passing 1Hz Landcruisers on hills, whilst towing my 1.5t trailer loaded with veggie oil and all the supplies for 6 days and 24 people. EGT remain completely under control and even pulling hard up a long hill, passing a long road train and accelerating to 130kmh, EGT only slowly climbed to 600°C - very satisfactory.  Soon the top of the hill arrives and I backed off to cruise at around 300°C at 100kmh towing the trailer. This reduces to about 260°C at 100kmh unloaded. 

This long run resulted in excellent fuel consumption and in fact better than with the old turbo. This was a surprise to me and I was able to get about 7.2km per litre. This was travelling at 80-90kmh on dirt often in 4WD, and 100kmh on the highway, and towing the trailer. The explanation for improved fuel economy is simply the extra air being blown by the turbo, improving efficiency. These results are on 100% WVO as fuel. Diesel, or biodiesel are likely to be better. 

The even better news was the lack of any noticeable change in oil consumption caused by the sand dusting. No extra blow by, no extra oil consumption, great power - great outcome. THANKS Graeme!!!  http://gturbo.com.au

Oh, one more thing. The waste gate fitted to the Grunter has a preset pressure of around 19psi, which is what I was needing. So I have removed the adjustable waste gate controller bleed valve.

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