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| Cooling Water System |
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Radiator
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| Stage 01 Modifying Radiator | |
| I changed the radiator from a divided 2 pass to a 1 pass. | |
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By that I mean, in the divided 2 pass, the left hand engine water (1/2 water flow) outlet goes into the top left hand side of the radiator, then passes through the top 1/3 of the radiator to the right hand side, where it mixes with the return water from the right hand side 1/2 water flow) of the engine, then this combined total water flows back in the bottom 2/3rds, to leave at the bottom of the left hand end. removed the baffles segmenting the radiator, plugged the left hand side return, put another return connection on the right hand side, and piped the return from the left hand side to the right hand side of the radiator, where both returns now mix and flow from right to left thru the radiator. |
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Improved efficiency - you bet. |
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Ambient temp Engine revs Cooling Fans Electric Water Pump Left Hand Bank Right Hand Bank |
: 35 Deg C : 2,200 RPM : Both off : Ticking over at 3.4 Volts : 92 Deg C : 90 Deg C |
Stage 02 Aluminium Radiator
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For both my XJ6 and my XJS I use a Commodore VT VX V8 Gen3 Alloy Radiator (available on eBay $180) which fits in place of the existing copper radiator, but is thinner, lighter and much more efficient (handles the 450HP of my XJS). Being thinner than the original copper radiator at around 40mm thick, it allows more room to the front of the engine for easier access. |
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Cooling Fans
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The modern trend in the automotive industry is to use high capacity electric fans, replacing the belt driven fans thus reducing weight for the crankshaft to spin. Air flow for belt fans are directly proportional to engine rpm, at idle slowest, at speed on highway highest. Electric fans, once turned on, are running at maximum capacity, even though the vehicle may be stationery. The electric fans run only when necessary, so there are fuel savings too. |
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The twin fan/shroud assembly fitted to the Falcon ‘AU’ onwards models, are close enough to the radiator size of XJ / XJS to fit (available on eBay for $165). The original outer mounting lugs (for the Falcon) are cut off. A small right angle bracket can be made and bolted onto the top of the shroud, bolting to the panel across the top of the radiator. |
The original outer mounting lugs (for the Falcon) are cut off. Two small right angle brackets can be made and bolted onto the top of the shroud at each side, bolting to the panel across the top of the radiator. |
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A bracket can be made and bolted to the bottom radiator cross panel, don’t bolt to the fan shroud, leave a ½” gap put in a tight fitting rubber packing piece. This way, if you need to remove the fans at any stage, you only need to undo the top bracket bolts, remove the panel across the top of the radiator, and lift out the whole fan assembly. |
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The V12 engine has a history of damaging the key-way at the front of the crankshafts, as well as destroying the harmonic balancer. Any driven weight saving here should be an advantage. Also with the V12, it is relatively easy to mount the alternator where the air pump is situated, reducing the belts on the V12 from 4 to 2! |
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Electrical connections for each fan are separated in a 4
spade socket so that individual switching for each fan can be done. (eg
one fan can be switched on with the air-con compressor). |
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The A/C compressor has a feed through a refrigerant pressure switch to one fan relay to bring it on when the A/C is operating and reaches optimum condensing pressure, reducing running of fan at highway cruising. |
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Electric Water Pumps
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| Stage 01 - Single Electric Water Pump |
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I removed the thermostats, crossover pipe and complete belt driven water pump assembly. Made up a flat aluminium plate with hose connection to go in place of normal mechanical pump.
Within the block, removed impeller guide vanes to give less restricted flow to each side of the block. |
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Installed an EWP120 Davies Craig Electric Water Pump in a standard off the shelf right angle hose from radiator outlet to pump inlet, where the original expansion tank was located, and another standard off the shelf hose from the pump outlet to the engine inlet connection. |
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In place of the crossover pipe connection, I tapped a 1/2" BSP thread, inserted an aluminium thermo well pocket that I machined up, and inserted into the thermo well the sensors for the electric water pump. |
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The electric water pump has an electronic controller that senses the water temperature and varies the speed of the pump accordingly for water flow requirements. The temperature is set to start the pump circulating when the engine commences to warm up, achieving increased flow as the engine comes up to normal operating temperature.
The electric fans cycle on/off on their independent two step thermostat (Tridon TFS 208) set to normal operating temperature, giving an extremely efficient and energy saving system. |
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Installed A VDO 230.054 temp switch (On 100 Off 95) in the rear right hand water rail, whereby after engine shut down, one electric fan and the electric water pump run to maintain water circulation until the engine water temperature has reduced to 950C, when they then shut off. This prevents heat soak into the heads - a phenomenon we are all very aware of with our Jaguars. |
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Stage 02 - Twin Electric Water Pumps
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Removed the single electric water pump connection plate, and made up a new plate with two connections, one into the left side and one into the right side of the engine, supplying cooling water directly into the opening of the block. |
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Installed the LH EWP80 in the LH front mudguard, and the RH EWP80 in the RH front mudguard. The pumps are controlled together by their electronic controllers, working in parallel, to maintain engine temperature, without the need for any thermostats restricting the cooling system. |
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Cooling Water Header & Expansion Tank
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With the removal of the mechanical water pump, expansion tank and overflow tank from the inner guard, I had fabricated a new stainless steel header tank and aluminium expansion catch tank, and installed them at the rear of the engine bay next to the washer bottle. This tank has the single radiator cap for filling the system and pressure relief, with excess water piped to the catch tank located beside the header tank, eliminating the rust creating tank in the inner guard. |
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Swirl Pots & Inline Filters - Stage 01
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| To completely eliminate air from the engine and eliminate hot air pockets, have fitted an inline swirl pot to each engine cooling water outlet, with a 3mm hose from the top of each pot, piping back to the header tank, so any air will be taken out of circulation straight back to the header tank . Inline filters have also been fitted to each cooling water outlet pipe to remove any particles from system. |
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Swirl Pots & Inline Filters - Stage 02 - Engine Rear Water Outlets
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| To overcome the problem of water temperature difference from the front of the engine to the back of the engine (normal running can be up to 15 DegC and on the track was getting up to 25 DegC difference) I removed the front water outlet headers and replaced with rear ones modified to eliminate the thermostats and have the front engine water flow to the rear outlet headers. An 1 1/4" outlet was welded to each rear water outlet header, and all return water taken from the rear of the engine back to the radiator. I then tapped the outlet of each water outlet header 3/4"BSP, screwed in a 5/8" tail, and fitted 1/2" hose from front water header to rear water header. This imposes a restriction on the water flow, reducing the amount of water from the front water header outlet, forcing more water to the rear of the engine, reducing rear engine temperature so the temperature difference between the front of engine and rear is now between 5 - 70C. |
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 Rear RH water header |
 Front RH water header |
 Front RH water return |
 Front LH water return |
 Front LH water header |
 Rear LH water header |
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The EWP control sensors are located in each front water outlet header. The Wolf engine management computer sensor is located in the front LH header, together with the VDO shutdown temperature sensor. In each rear water outlet header is a water temperature gauge sensor to give temp readout of each outlet at dash mounted gauges. The heater water supply is taken from the rear LH water outlet |
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Glycol and its alternatives
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All vehicle manufacturers advocate the use of glycol antifreeze solutions in their cars They do this as a blanket statement to cover every eventuality for the broad range of conditions that vehicles are expected to operate under, from the Sahara Desert to the snows of Scandinavia.
Much has been made by promoters of safe non toxic personal care toiletries and cosmetics of the potential dangers of known "safe toxic" chemicals such as Propylene Glycol and Ethylene Glycol, a related chemical. Although exposure to high levels of Propylene Glycol is known to cause serious and potentially irreversible health conditions, the chemical industry tell us that "small" quantities or low level exposure of Propylene Glycol is "safe" to use on the skin and in food.
According to the safety data sheets of industrial chemical manufacturers, chemicals such as Ethylene Glycol and Propylene Glycol will cause serious health conditions, including liver and heart damage and damage to the central nervous system if sufficient is absorbed by the body.
Ethylene glycol and propylene glycol are clear liquids used in antifreeze and de-icing solutions. Exposure to excess amounts of ethylene glycol can damage the kidneys, heart, and nervous system. Eating or drinking very large amounts of ethylene glycol can result in death, while large amounts can result in nausea, convulsions, slurred speech, disorientation, and heart and kidney problems.
Antifreeze over time becomes acidic, causing corrosion to metal parts of the cooling system, and in fact can turn the whole system into a battery whose anodes (typically the aluminium parts) are consumed. This is why antifreeze solutions in your engine must be flushed regularly and replaced, usually every 2 years. |
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| Luckily here in Lake Macquarie, Australia we live in an area where the ambient temperature doesn’t fall low enough to warrant an antifreeze solution, so there is no need to add glycol to our cooling water systems in our cars, and we don’t need to drink it to protect ourselves. | |||||
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Running plain water is not a solution;
our engines require an anticorrosive agent to stop corrosion and
electrolysis, while the water pump and seals require lubrication to
prevent cavitation, for efficiency and prolonged operating life. On the TWR race cars they ran braided hose from the back of the heads through a bleed valve back into the cooling system. |
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As noted above, on my V12, I have modified the return water relocating the water outlet from the front of the engine to the rear, to increase the volume of water to the rear of the block and heads, to help overcome this problem. |
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In place of antifreeze, for 10 years I used Tannin tablets that provided the corrosion inhibiting required, and for the last 3 years I have used Millers Rad Hib Extracool, a water wetter additive.
Water wetter is one of few things that does actually help - the science behind it is quite sound. It won't necessarily reduce the temperature readings, but it will improve the engine's ability to survive running on the edge of overheating. It does this by preventing hot-spots.
What happens is that in every engine, due to the nature of the coolant passages, hot-spots develop. If the coolant in those places starts to boil, the problem gets exponentially bigger because steam is a good insulator, which makes the hot-spots get even hotter. Water wetter breaks down the surface tension of the coolant, which makes the boiling bubbles much smaller, thus reducing the insulation effect of boiling over, and thus improving the engine's chances of surviving overheating.
Technical Details
WaterWetter® is a unique wetting agent for cooling systems which reduces coolant temperatures by as much as 15ºC. This liquid product can be used to provide rust and corrosion protection in plain water for racing engines, which provides much better heat transfer properties than glycol-based antifreeze. Or it can be added to new or used antifreeze to improve the heat transfer of ethylene and propylene glycol systems. Designed for modern aluminium, cast iron, copper, brass and bronze systems.
· · Doubles the wetting ability of water · · Improves heat transfer · · Reduces cylinder head temperatures · · May allow more spark advance for increased torque · · Reduces rust, corrosion and electrolysis of all metals · · Provides long term corrosion protection · · Cleans and lubricates water pump seals · · Prevents foaming · · Reduces cavitation corrosion · · Complexes with hard water to reduce scale |
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| Products Available | |||||
 Millers Rad Hib Extracool |
 Redline Water Wetter |
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