Why Performance Diesel Intercoolers?

The PDI kits were developed to optimise the front mount installations and get the best components for the best flow.

A key aspect is that these are designed for off-road vehicles for those who want to take their 4WD into some of the harshest locations possible while providing trouble free performance.

We use the largest cores for the location and typically use bar and plate design as they are regarded as being of more durable construction and typically are able to handle the higher pressures.  We are investigating the use of tube and fin designs as an option.

The pipework is 304 stainless steel and mandrel bent where possible.  The ends of the pipes are prepared with a higher than normal flare to prevent the silicon hoses slipping off when the system is hot and your boost has hit 35-40psi.

Our silicon hoses are custom designed (where required) and constructed from 5 fibre layers within a total of 6mm thick material for maximum resistance and longevity.

Breeze Aero hose clamps are standard with our kits since we have found them to be the most reliable. T-bar clamps look impressive and do work, but the most reliable we have found is the conventional screw type Breeze clamps.  They can take a surprising amount of torque and I have only damaged one from over torqueing it.

Brackets are made from mild steel for fatigue resistance and the use of a support bracket for the bonnet latch instead of asking the aluminium intercooler to do the work.  If you hit some of the tracks in Australia, you will find we have the worst corrugations in the world and it is amazing what they break off and shake loose. The brackets are zinc plated and painted for protection.


What’s the impact of a FMIC on EGT and engine coolant temperatures?

Exhaust Gas Temperature (EGT) is measured in either the exhaust manifold or exhaust pipe. It is an indication of cylinder combustion temperature and will never be as high as actual combustion temperatures due to dissipation of heat into the cylinder head and pistons. 

On diesels, a fuel rich burn will result in higher combustion temperatures. This is the opposite to petrol engines, where excess fuel is added under load and rather than being burnt, it evaporates and causes cooling, thus protecting the pistons and valves.

Back to diesels, cooling the compressed air charge, through intercooling, will result in a leaner (cooler) mixture can being achieved. From a performance perspective it means that the system can be pushed harder with more fuel being used to burn the extra oxygen.

An effective intercooler will reduce exhaust gas temperatures by over 100degC and get within a few degrees of the ambient temperature.  This means that critical engine components can operate at a safer condition while still under heavy load.

This reduction in combustion temperatures is extra heat that does not need to be removed through the radiator. As long as your cooling system is functioning correctly there should be no change through the fitment of a FMIC.


1HZ overheating?........again.

The 1HZ has a great reputation for a solid worker.  It also has a history of cracked heads and pistons with the early turbo systems with plenty of experiences of overheating.  

The 1HZ is Toyotas indirect injection 4.2L, as opposed to the 1HD series that are all direct injection. Toyotas casting is very consistent but in the case of the 1HZ there is very little water jacket around the exhaust port, which means that when fuelling is increased (for more power) without sufficient air,  the combustion temperatures rapidly rise and subsequent EGT becomes excessive. The steel around the exhaust port gets hot and expands, without the water presence and flow to equalise the temperatures in the steel around - this uneven rapid heating places the steel under stress and may result in a crack.

For demonstration a 1HZ cylinder head was cut through the exhaust port.  During the cutting the internal stress resulting the in cut area opening up before the cut was complete. An inspection of cross-section shows the small water gallery around the port.  Looking inside the water gallery a layer of rust and scale can be seen, which acts to reduce the gallery size and insulates the coolant from the steel.  The scale is very hard and can only be lifted with a chemical treatment.

To have a successful experience with a turbo 1HZ:

  • Use a turbocharger that boosts early and is on boost under normal driving rpm.
  • Tune the system to have a lean burn when loaded up.  
  • An efficient intercooler to get maximum cooling and lower EGT.
  • Run 15-18psi as this works well with the fuel capabilities of the std 10mm pump.
  • Don't let the engine lug in the lower rpm with rich mixtures.
  • Run Toyota Red Long Life Coolant (thats not the Extra Long life coolant).  Don't mix coolants and flush if you have.
  • Clean the cooling system with a quality engine flush to remove rust and scale (R20 is a great corrosion dissolver and can be left in the engine for a week or more).
  • Run a genuine thermostat.
  • Consider adding extra fluid to the viscous coupling to make it pull more air.

Difference between Air-to-Air and Air-to-Water Intercoolers.

Air to water intercoolers were an ideal choice where packaging was limited and were found in a Subaru WRX and the Toyota GT4 amongst other models.  The Ford F250 Lightning also had an air water intercooler as it allowed it to sit under the superchanger in the middle of the V8. The water in the system increases the thermal capacity of the system so for short duration load situations they can transfer the heat out of the air into the water which is also cooled by the movement of air when not under load and when pumped through the heat exchanger.  

Diesels engines are great for constant load so very quickly the thermal capacity of the water is exhausted and the water must be cooled via an electric water pump through a heat exchanger located outside the engine bay, normally in front of the radiator. Where the heat exchangers are smaller than the front mount intercoolers they cannot be expected have the same cooling capacity.

The air water systems can be made to be very effective and where space is an issue they can be best and only choice. Often getting a functional system is harder than it might seem.

The “trouble” with air-to-water intercoolers.

1.     In diesel engines the compression ratio is very high (17-22:1) with limited space above the piston when is it fully up.  Water is not compressible and when injested it normally results in bend conrods and an engine rebuild.  All it takes is a hairline crack from a manufacturing fault or fatigue after a trip down a rough road. After parking the vehicle for a few hours or days the water can fill the turbo or manifold and on the next startup the engine damage is done resulting in a complete engine rebuild.

2.     You have an extra cooling and electrical (water pump) system to maintain.  If the water level drops you can have component failure and if the system is not functioning consistently the tune applied can end up running rich.

A number of our customers are sick of the water level dropping and the difficulty of having to bleed air out of the system.  The upgrade to one of our front mount kits has been without a loss in performance and becomes a completely maintenance free system without the worry of killing the engine from water ingestion.


Top Mounted Intercoolers

The installation of a top mounted intercooler has a certain cool factor in that you get a tough looking bulge in the bonnet.  From a heat exchange perspective, it is not all that cool. From a safety perspective, since the bonnet is part of the impact zone and passenger protection the introduction of a hole, cutting through bracing is not that cool either.

The top mounted intercooler system is affectionately known as an "inter heater" since it is placed on top of a hot engine with the extra heat from the exhaust manifold, turbo and exhaust system.  Heat is radiated from the engine and as heat rises it is also affected by convection.  Both of these affects can be reduced (and overcome) with a scoop and thermofans providing the air flow over the core is sufficient.

We have yet to see a top mounted intercooler feel cold on the cold side of a running engine, even if it has only been driven mildly.  It is always too hot to touch.  

A common misnomer is that front mount intercoolers only work well once moving and that a top mount is good for slow speed.  In a stationary situation on a dyno, (without a cooling fan in front of the vehicle) our front mounts prove to be more consistent in repeated high load runs.  Shortly after the run, with the engine still running, the huge amount of air that is pulled through by the engines main fan cools down the intercooler outlet, pipework and even starts to chill the intake manifold.

Another assumption is that the bonnet scoop will actually scoop the air that you can feel against your hand or face when stuck out the window. The shape of the car will produce high and low pressure zones and also areas where there is not much air movement at all.  The installation of a bullbar with the top bar (and / or a light bar) in front of the scoop will affect the air flow across the top of your bonnet.  A HZJ or HDJ 70 series has such an issue and as water sitting on the polished bonnet will show - it is not until you get to around 90kph that the water will start to move towards the windscreen. Its little wonder that those who measure the outlet temperatures of their top mount intercoolers are not impressed.


Front Mounted Intercoolers - The Evolution of the Species.

Nowadays all modern diesels vehicles are sold with turbochargers. This is not because it is cheaper to produce, but because the market and emissions requirements dictate that it must be so.

Similarly it is with intercoolers, where initially turbo diesels were not intercooled from the factory.  Due to the obvious benefits of intercooling, the first models had top mounted intercoolers as that was the easiest to install on the production line where the intercooler is part of the engine package that was bolted into the chassis with the rest of the drivetrain and then the body was installed.

As is the case with performance street cars, the intercooler was moved to the front for optimum benefits.  This can be seen in the 3L D4D powered Prado where the 150 series (front mounted intercooler) has better onroad power and torque over the previous 120 series with its top mounted intercooler.

Adding a top mount intercooler or increasing the size of your top mount intercooler will make a noticeable improvement.

Changing to a front mount installation is the next logical step.  In the same conditions the inlet air temp can be expected to be 20-150deg cooler with a top mounted intercooler, which equates to more than 20-40% more air and therefore power potential.


Do you expect more lag from a Front Mount Intercooler?

The theory here is that the increased intake volume will increase the time it takes to fill the pipe at the higher pressure. The larger the pipework the greater the volume.  Initial testing showed that the 2.5" pipework was ideal for the air required to meet the fuel delivery capabilities for the engines covered. 2" pipes are easier to route in tight engine bays, but will choke the potential.

On a Landcruiser 1HDFTE with around 160rwkw, a check was done with no intercooler and then after the Performance Diesel Intercoolers Front mount kit was installed.  The results showed the boost built slightly quicker with no intercooler, but almost immediately the intercooled setup built torque faster and was much stronger throughout the rest of the power range. There was a 50rpm range where no intercooler was better.

The test clearly showed that lag should not be something to be concerned about when considering a PDI front mount intercooler kit.


Is heat sink an issue?

Its more of an attribute than an issue. Until the intercooler and intake warms up, the result is a cooler air charge for combustion, which is good.  Once warmed up (after a loaded run) then it will make the air hotter than it would otherwise be, which is bad. When loading up with increased boost the post turbo temperature will rise almost instantly. For short duration bursts an increased heat sink will stop the outlet air temperature from rising quickly, but that heat still needs to be dissipated.

All intercoolers for road going vehicles use the air at ambient temperature as the heat exchange medium.

The more important attribute is to ensure the core design allows for maximum heat extraction.  This is done by optimising the size of the core and by ensuring the best flow of air over the core. With the intercooler placed between the grill and radiator, the exposure to the coolest air is maximised for both when moving and when stationary.  OEM viscous coupled fans speed up when the air temperature behind the radiator increases, which is why your air conditioner continues to work while stationary and your engine doesn't overheat.  A front mounted intercooler continued to take advantage of this.


What about the heat sink of end tanks?

If we consider the physical design of a bar and plate intercooler core.  Taking a sample which has 28 internal fins 7mm across the width of a 76mm core, which since both sides are exposed is around 40cm of aluminium the air must travel per internal core. For a core 550mm long and 300mm high that equates 3.5 square meters of metal that air is forced to travel very close to.

The internal cross sectional area of the inside of the end tank is far less (0.1 square meter) and most of the air is not forced to travel close to the end tanks either.  Any heat transfer back into the air flow is going to be minimal.  Whatever improvement for using a thinner material on the end tanks to reduce heat transfer can only be applied to the 0.1/3.4 = 3% so an optimistic 20% reduction in transfer capability by reducing mass of the end tanks may improve efficiency by 0.6%, thats if heat sink is indeed an issue.

Correctly designed cast tanks are going to flow better with smoother internal transitions and they are not going to split along a weld. 


Whats the story with the green 80 series in the photos?

I’ve got great memories of the awesome adventure I took in that car. It was an expedition to Magadan on the Road of Bones with our friends at 4x4 World Explorer and the photos are taken in Siberia.

For starters we picked up an 80 series locally with a petrol engine that ran well, but wasn’t suited to the vehicle’s upcoming life touring the world.

On a previous trip along the Canning Stock Route with Thomas and his friends at 4x4 World Explorer, I’d noticed (and discounted) a 105 vehicle with a wrecked body, but had za good chassis. After my return to Perth when I decided I needed one for a Lexus LX470 bodied, 1HD-FTE powered 105 I made contact with the owner. We found that the 1HZ motor seemed okay, but started and stopped with a problem that was likely related to the electronic controls on the injection pump.

With the body off, we cleaned up the red mud off the 1HZ, installed it into the 80 with a Grunter Extreme from GTurbo and a large bar and plate front mount intercooler and exported it to Kuala Lumpur for the start of it’s adventure. We kept the Eastern Goldfields 4WD Club number plates in recognition of it’s past touring the interior of WA. The very first owner turned out to be a mate around the corner who proposed to his wife with this vehicle!

So with plenty of adventures already under it’s belt, my friend and his son joined the convoy from 4x4 World Explorer and drove north from Kuala Lumpur, through Thailand, the mountains of Laos, and into China.  I joined them in northern China with my wife and father in law and we headed west into Mongolia, then north into Siberia where the real adventure began and the party thinned out.

Over the next month we made our way along the renowned Road of Bones to the farthest eastern part of Russia accessible by road, and then to Vladivostok. Plenty of mountainous scenery and dirt roads with a few falls of snow just so we knew it could get really cold there.

Performance of the package with the GTurbo and front mount intercooler was exceptional. Fuel economy was far superior to the non aspirated 1HZ in the convoy, as was performance. The ability of the vehicle to easily maintain speed up the long mountain passes in China quickly became legendary as the other 1HZ’s fell away at the high altitudes.

Not only did this vehicle live a full life in the rough goldfields of Western Australia, and drive to the most eastern point of the Asian landmass possible, it’s next trip took it back into China, Everest Base Camp, Moscow, the top end of Norway, down the coast and into London. So it’s been the furthest east, the furthest south, the furthest north and the furthest west of the huge landmass of Asia and Europe. It’s completed a 2 month trip into Africa and next year will be off to South America for another 2 month trip as the main support vehicle so its heavily loaded.

These trips alone give proof to the capacity of a well tuned 1HZ to handle a properly matched turbocharger and the power and efficiencies of a front mount intercooler.