2 core versus 3 core radiators

[Alitis007]

A couple of urban myths I can see here, firstly running too cold mainly effects petrol motors coz the NOT (normal operating temp) is set to help atomise the fuel so the motor runs at its optimum unlike a diesel. The other is the tubes of a quality 2 core and 3 core sould be the same diameter meaning a 3 core is thicker than a 2 core radiator. The theory I have been told by a manufacturer is its is easier and faster to cool a small quantity or water rather than a large mainly coz of the core thickness which affects airflow thru the heat sink of the core. As a recommendation a 3 core radiator would be better suited for heavy towing on the freeway coz the the travel speed will aid in cooling the core.

This is what I was told and from my experience made sense to me with my experience but doesn't make it gospel either, your driving conditions will dictate which size core suits your application as I told you the other day Jonathan

[Alitis007]

Oh and the thermostat constantly opens and shuts untill the water/coolant on either side of it equalise and it stays open to allow the water to flow freely. This also should be chosen for you application, usually the temp range of it should be roughly 10* lower then where you want it so the standard 82*c will give you a not of 90*c which is fine for the areas we drive

[Bloodyaussie]

The thermostat won't stay closed. The thermostat will open when the stationary water in the engine reaches a certain temperature, allowing water to circulate through the system. When the engine temperature normalises, the thermostat may close a little or a lot to maintain a regulated temp. This is how it normally works. If the cooling is too efficient, that is the radiator is getting rid of ALL the heat, the maximum working temperature or the engine will be that of the radiator water. In other words the thermostat can only regulate what it has. If for some reason the water is too hot or too cold the thermostat can only regulate within that range.
IMHO the OME design of radiator, thermostat and system is probably best for the vehicle unless you are running in extremes such as cold climate all the time or very hot climate all the time. Increasing the number of cores may result in better cooling of the water but will also decrease the ID of the galleries in the radiator. OK if you always use good coolant in your radiator. Unfortunately, we tend to take our vehicles out and fill the radiator externals with leaves and mud and wonder why they don't perform as well as they did. There is always the possibility that an emergency in the bush may cause you to have to top up or even fill with not so pure water instead of coolant. In this situation it may be best to have as large an ID in the galleries as possible.

This was my understanding and in the past have had a problem with a Kawasaki Gpz900r that are well known for overheating so I had a late model sports bike radiator modified to fit but found it worked too well and had a canvas cover made to put on during the colder months... in summer it was perfect and I no longer had over heating issues but winter saw it struggle to get to operating temps.

So a good heavy duty 2 core should be fine then????

[nissannewby]

So a good heavy duty 2 core should be fine then????

Yes!

Diesels still need to maintain an optimum running temp as well. This is not an "urban myth".

[Alitis007]

Yes!

Diesels still need to maintain an optimum running temp as well. This is not an "urban myth".

So how does water temp affect performance? ? I know diesel is used to cool the injectors and injector pump thats why coolers are fitted to the return lines of the late model diesels and naturally diesels run cooler than petrols yeah!?

[nissannewby]

So how does water temp affect performance? ? I know diesel is used to cool the injectors and injector pump thats why coolers are fitted to the return lines of the late model diesels and naturally diesels run cooler than petrols yeah!?

Due to a diesels nature (compression ignition) if the engine is not at the right temp the combustion is harder to achieve and you can end up with something called diesel knock.

Have you never heard a diesel start when it's dead cold?

[Bloodyaussie]

Due to a diesels nature (compression ignition) if the engine is not at the right temp the combustion is harder to achieve and you can end up with something called diesel knock.

Have you never heard a diesel start when it's dead cold?

They sound awesome...... bit like me when I wake nowadays!!!

[the evil twin]

Oh and the thermostat constantly opens and shuts untill the water/coolant on either side of it equalise and it stays open to allow the water to flow freely. This also should be chosen for you application, usually the temp range of it should be roughly 10* lower then where you want it so the standard 82*c will give you a not of 90*c which is fine for the areas we drive

Uuummmm... yes and no.
I agree with the delta T across the thermo but not how it works

Thermo's aren't an open and shut device, they are dynamic.
That means they will begin to open at 'x' temp and be fully open at 'y' temp.
Traditional engine thermos are wax pellet versus spring but bi-metallic is slowly becoming in vogue

Using hypothetical numbers and ignoring bypass circuits for ease of explanation.
At 85 degress my hypothetical thermo begins to open and pass coolant with a much lower temp from the Radiator to flow thru the engine
The thermo will settle at a percentage open, lets say 10%, where the coolant takes on heat energy from the engine and circulates thru the Radiator and has a temp of say 90 degrees.

Once the engine load starts to get significantly higher the coolant exiting the engine rises to, say, 95 degrees the thermo will open a tad more.
Lets say it now finds equilibrium at 50% open and 95 degrees.
The thermo cannot start to close as the heat is holding it open against it's mechanical pressure trying to move it closed.

The only thing that will move the thermo either further open is a further increase in engine load and thus coolant temp or towards close is a drop in engine load and the thermo mechanical pressure overcomes the expansion and begins to close.

If the thermo gets fully open, lets say 105, there can be no increase in coolant flow and any more load will cause the engine to overheat.

It is precisely for the above reasons that virtually all vehicle manufacturers use non linear temp gauges without a numbered scale.
This is actually quite a good idea because the temp of coolant exiting a vehicle engine is never constant but if it is within the 'normal' range then who really cares.

As an example my CRD dash temp had no discernible movement from it's "happy spot" just under 1/2 of scale if the engine sensor was between 80 ish degrees and 100 degrees.
From 100 to 106 it would move towards the upper limit mark.

[Hodge]

As an example my CRD dash temp had no discernible movement from it's "happy spot" just under 1/2 of scale if the engine sensor was between 80 ish degrees and 100 degrees.
From 100 to 106 it would move towards the upper limit mark.

Mine is identical. Once it hits half way it does not move no matter what. Although once warm, I have NEVER seen my coolant temps go out of 86-91 range. I am reading that from my scangauge. How accurate would that be Evil??? I have really pushed the car a few times and highest ive ever seen was 91C.

Edit: BA probably hates me for hijacking the thread again :P

[the evil twin]

Mine is identical. Once it hits half way it does not move no matter what. Although once warm, I have NEVER seen my coolant temps go out of 86-91 range. I am reading that from my scangauge. How accurate would that be Evil??? I have really pushed the car a few times and highest ive ever seen was 91C.

Edit: BA probably hates me for hijacking the thread again :P

Haters just gotta hate

Mine used to wander between 88 and 94 just swanning around the place.
Usually sat on 88-90 or 90 - 94 with A/C on and a hot day

Beach work (very soft going here in SW of WA) or towing in 40 to 45 degree heat it would wander between low 90's to low 100's.

Your scangauge is showing the temp reported to the ECU from the engine coolant temp sensor.
It will be equally as accurate as any aftermarket gauge and better than some.
I confirmed mine as being close enough using a laser gun.