Engine Cooling

I have been thinking about additional cooling for quite some time.

Its not really a problem for my truck but for older vehicles or even ones frequently off road or in hot climates, is it wise to fix an auxiliary fan or even a intercooler?


Intercooler: I'm thinking that driving at very low speed in lo ratio for hours on end @ 2000+ rpm will soon heat up the motor. What if the engine in question is a non intercooled model like many earlier Japanese 4x4's? My understanding is that a intercooler not only allows more denser air in to the engine but also lowers the air temp from the turbo. So regardless of any small or large power & torque gains if your motor does not have one would it be better to get one installed to help maintain lower running temps?

Fans: Is it a good idea to install a second electric fan, like the Kenlow fans? Or even remove your factory fitted fan from the engine and replace that with a switch operated electric one? - Possible improving in small amounts of power and fuel economy, with the ability to turn the fan off and not douse the engine in water during a water crossing?

Driving along sand and dunes with your overland vehicle kitted out and loaded up, the engine cooling could be pushed to the max. Ive not done alot of sand driving, but loaded up it felt like towing a trailer with the brakes locked on. And I can imagine that covering possibly 100's of miles like this at varying speeds and rpm the motor will be running hot.

So is additional fans or even the installation of a intercooler something that should be done or well avoided as another potential thing to go wrong and break down?


Jas

Jas.

A note...It's low RANGE please. Low ratio is the main gearbox. The lowest ratio being the 1:1 top gear....Never mind. Land Rover don't know the difference and neither do most motoring writers.

High ratio = Low gearing. Low ratio = High gearing.

My Defender only has a Kenlowe fitted. I've not had any problems at 45Deg C plus while driving the sand and gravel roads in Namibia. I would think the GVW of my Defender in those places would be arround 3,500kg. The fan on mine is controlled by a thermostatic switch, with an override switch.
I have a very accurate full face water temperature gauge with an adjustable warning light setting. Set I think at 96Deg C

One of the best things you can do, if possible is more water above the engine.

As you are travelling very slowly. No air is pushed throuigh the intercooler except that pulled by the fan.
Personally I would like to be able to fit a fixed fan for those conditions.

I've driven in South of Spain/Morocco/Algeria/Niger/Mali/Mauritania/Senegal in a standard Range Rover (cooling system-wise) and Malaysia/Thailand in a standard Land Rover Series and Defender, and never had a problem with overheating ... and that is everything from desert rallying to plodding though dense vegitation in the jungle. Surely the same should go for modern Jap vehicles?

As you say maybe it's a problem for older Series Land Rovers, but for modern vehicles (Range Rover 1970 onwards) it shouldn't be an issue ... should it?

No additional cooling will be required as the cooling systems are "Non-Proportional" cooling systems, so what are these.

There are two types of cooling systems, proportional and non-proportional systems.

Proportional cooling systems work on the ram air principle, basically this means the cooling air is proportional to the vehicles speed as the engine runs at consistent speeds in relation to the airflow, as an example a road car travelling at 70 MPH has air passing through the radiator at 70MPH with the vehicle in top gear with an engine speed of 2500 RPM.
This is consistent as the vehicle speed, engine speed, and gears are all proportional, the vehicle may travel at 70 MPH in fourth, fifth, or sixth gear, but in real world driving it would only do this in sixth gear for sustained periods, any other time may only be for short bursts such as accelerating for maximum speeds in each gear, but it is only short bursts.

Non-Proportional is the exact opposite, true 4X4 vehicles with low range may use the same power and engine speeds, but using lower gears (low range) and heavier engine loads, but will be travelling at much lower speeds, so they do not receive the same ram air effect, or airflow as they are travelling much slower. This means their airflow is not proportional to the engines and vehicles road speed.

To compensate for this, and the fact that 4X4's may run at high engine revs to power accessories such as hydraulic power take offs, hydraulic winches, or any other accessory; the designers compensate by improving the cooling systems capacity to compensate for such eventualities.
Other factors also come into play, an average road vehicle will only get normal debris such as road dirt, flies and insects, and leaves in the radiator, 4X4's on the other hand will often get covered in mud and this will impede airflow through the radiator, again this is compensated for by an improved cooling system.

On a road car the only time the system will be tested is during a high speed run such as travelling down a motorway at the national speed limit, then having to suddenly stop for an accident, the same heat is there but the airflow suddenly stops, then we have a condition called heat soak. Heat soak is when heat is there, but the cooling air stops flowing suddenly, and the normal ram air effect cannot cool the engine, to compensate for this the manufacturers fit an electric fan, this suddenly cuts in and the engines temperature rises slightly for a few minutes as the fan dissipates the heat from the radiator. This is caused by the loss of cooling air, and the slowing down of the water pump speed as the engine is now idling so the coolant circulation is also slower, this means the fan has to work hard to cool the engine, and the slower coolant speed means it takes longer for the cooled coolant to get back to the engine block to cool the engine. This is why the temperature rises slightly for a few minutes until the now fan cooled coolant is circulated back to the engine and cools it.

While your logic has some merit, it is flawed, the cooling system is designed to cope with all these conditions, and has a large degree of overcapacity to cope with maximum vehicle loads, towing the maximum weight, and in all the worlds temperatures. How often do you fully load your vehicle, tow 2800KG, and all across the Sahara Desert? not often. But your cooling system is designed to cope with such conditions, and all while covered in mud; the only thing you need to do is keep the cooling system maintained and run the correct anti-freeze mixture which is not difficult.

As for fitting an intercooler, Hmmm; why? all this does is cool the air going into the engine making it more dense, this allows more fuel to be injected, and give more power, in return this additional power produces more heat which may raise the engines heat output above the designed cooling systems heat dissipation levels, and lead to overheating anyway. Particularly when travelling in low range with a heavily laden vehicle.
Electric fans are not a good idea on any true 4X4 as they are weak, they hate water, mud, and anything on their blades as water will damage the motor, and any mud on the fan will overload the motor and burn it out, or seriously reduce its life, and the reason many true 4X4's have viscous couplings on cooling fans, or direct engine driven fans. Viscous couplings are sealed oil driven fans which alter the quantity of driving oil in relation to heat, much like an automatic transmission, they are sealed, and both these and direct driven fans have the power of the engine to drive them, so no shortage of power, and no weak electric motors to burn out at the most inoppertune time when they are most needed.

Manufacturers of true 4X4's also take other steps, if the vehicle is an automatic it will have a transmission fluid cooler, this is standard on most auto vehicles, but on a 4X4 it has a much greater cooling capacity to cope with the lack of airflow, mud and debris, and higher torque loadings which all add up to more heat.
Oil coolers are now almost universally fitted to true 4X4's, again these work in conjunction with the water cooling by cooling the engine oil and reducing the strain on the cooling system.

Bet you're glad you asked now.

Two things -
firstly, I've spent quite a bit of time in deserts and with a standard 4x4, unless there are known issues, there is little need to add extra cooling. They cope well enough. If you are travelling at the hottest pat of the day at the hottest time of the year - you're doing something wrong anyway.
Secondly, in reality very little time in comparison is spent in low range unless you are traversing a dune field.

Still glad I asked, picked up a few things already.

Assassin wrote:

Bet you're glad you asked now.

As i knew it was you asking i could put an in depth reply, and i knew you would understand it and absorb it to learn a little more.

Thats why i like this forum.

I'm sure other users also find your input beneficial as well.

Thanks Assassin

Quote :

If you are travelling at the hottest pat of the day at the hottest time of the year - you're doing something wrong anyway.

I guess that I am doing something wrong then

The main problem I have in the Series is that the temp inside is a lot hotter than the temp outside - normally about 10-15c - (so when it 45c, the cab is a bit warm!) but worst than that - everything metal is the cab is boiling to the point it will burn you! My solution is to fit rubber mats on the floor so I dont burn my feet at least!

Onlymark:

Your synopsis is incorrect as many vehicles often spend more time working in low range for the majority of their lives, and ultimately it comes down to the working conditions of a vehicle, during my time in the mining industry all our LR and Fourtrak's would remain in low box most of the time.

It would be fair to say it depends on the vehicles and individual working conditions.

Just fitted a pair of Kenlowe fans to my Range Rover 'ambulance-soon-to-be-camper', they work a treat.

Although mine came with the vehicle, Kenlowe fans can be picked up at 4x4 autojumbles for pennies. When you add a new electric thermal control from Kenlowe themselves (all in with VAT and carriage - £31.30) it's a simple, cheap way of solving most overheating problems. Set on halfway twixt hot and cold, should I be towing or driving in a hot region, it has plenty of leeway to increase the cooling if required.

As I always say when it comes to such matters ... K.I.S.S!!!

Try an aluminum radiator.

What are the benefits of an aluminium one over a factory radiator?

TJ

Please Google "brass vs aluminum radiators" for a comprehensive answer.

Many different opinions by many people but they all seem to say Aluminium is better.
Mainly Lighter and Quote "According to Liquidcooledairpower.com, the thermal efficiency of aluminum radiators is approximately 60 percent above that of copper or brass radiators"

Read more: Aluminum Radiator Vs. Brass | eHow.com http://www.ehow.com/facts_7556066_aluminum-radiator-vs-brass.html#ixzz1ZKj0epjl

TJ

Yes, and stronger as well.

This is actually a myth as aluminium radiators are not better at heat dissipation then an ordinary copper radiator, its all down to the design of the individual radiator, its thermal transfer rate, and cross sectional area.

Aftermarket aluminium radiators are not necessarily stronger either, those using the correct grades of aluminium are, those numerous cheaper items are made from inferior materials which are prone to cracking at the edges of the welds.

Aftermarket radiators are generally better designed as original components are built to a minimum quality, but ultimately down to a price so the manufacturers make more profit, and they wear out so they sell and fit you another.

Actually, Assassin is correct. Brass is a better dissipator of heat than aluminium, but a well designed and constructed aftermarket aluminium radiator is better than a brass OEM unit, and design and construction wise, you can do more with aluminium than brass or copper. Virtually all modern race cars use aluminium radiators for various reasons, one of which is superior cooling combined with strength and light weight.

I can tell you from experience and empirical tests that a good aluminium radiator is better than an OEM unit. All my Samurais have aluminium radiators which replaced stock OEM units and dropped the temp. by 5-6 centigrade using the stock fans and shrouds. Further improvement could have been obtained by fiddling with various fan options. But even running the rigs through sand for hours on end, I could not come close to overheating. We're talking here about ambient temperatures of 40 centigrade which gave me coolant temps. of 85 centigrade. Under most conditions (36 or less centigrade) the thermostats don't even open.

Thanks, guys.