The V8 Owners Forum -

Hello all! New member to the forum, but I have had my Westfield now for 15 years since I built it, but have always had similar problems with cooling.

My Westfield SEight has always suffered from not so much overheating, but running at high temperatures; roughly 98-100 degrees. By running a second radiator from the back of the Offenhauser manifold and back through the return to the pump I have managed to stabilise the temperature at low revs and in standing traffic and avoid overheating. As the diagram below shows, I am using the 5 core aluminium radiator supplied by Westfield. The secondary radiator has been bypassed at the moment to try and eliminate it as a problem. Both radiators have fans; the main radiator is operated on a thermostat (with override switch) and the secondary radiator is on a manual switch only. Has anyone got any ideas of pointers regarding the plumbing of the system to help reduce the temperatures down to the recommended/usual levels?

The engine is a 3.5 Rover V8 compression raised to 9.75:1, with a fast road cam, polished ports and valve springs to suit. The carburettor is a 4 barrel Edelbrock 500cfm through an Offenhauser 360 dual-plane manifold.



Any help greatly appreciated!!

Hello Westy, I dont think your answer lies in changing any of the plumbing although, it does seem that the cooling function is slightly too weak, as witnessed by the effect of adding the second radiator.

You have not mentioned whether the main radiator fan is trying to push air through the fins or drag it through.

Pushing air through, results in a lot of deflection and unproductive turbulance.

Dragging it through mean the airflow is much smoother with no deflected or wasted fan effort.

You also mention a 5 core radiator. Thats a lot of cores for the air to pass through, and they all have to be effectively capable of transferring their heat to the passing air.

Just possibly, the heat transfer of the last 1 or 2 cores is limited by the amount of heat already absorbed by the moving air, so the cooling process efficiency is impaired. So, more air flow may be called for - see later.

Your system design appears to be capable of maintaining a reasonably stable temperature when running at or around the 100 deg C mark and because you are simply running too hot as opposed to suffering surges of overheating then I suggest two discrete actions, designed to improve the extraction of heat from the radiator fins and/or to do it sooner.

1 Change the main fan/radiator thermostat switch to a lower temperature unit.

AND

2 Increase the air flow over the radiator fins by one of the following methods
. a) increase fan diameter
. b) increase the number of fan blades
. c) increase the pitch of the fan blades
. d) increase the fan speed

That way the "fan cooling" part of the heat transfer process - as opposed to the "ram air" part - starts a little earlier in the temperature rise cycle and with the fan running sooner your temperature may not be going to get so high.

And of course, the increased air flow speaks for itself.

It's debateable, but you might also get some mileage out of fitting a lower temperature thermostat.

Essentially the thermostat primarily determines the point at which the cooling process actually commences, but because it starts a little sooner, it may also have the effect of limiting the maximum temperature achieved. But like I said, its debateable.

There is also another another factor to consider. The type of fan control being employed. Think about it this way?

On the original Rover V8 system the main cooling fan was a viscous unit with its temperature sensing element immediately behind the centre of the radiator, so as to minimise the delay between the sensing of the critical temperature to engage the fan and the virtually instant cooling effect of the engaged viscous.

It was also a very subtle system that had a variable effect on the viscous fan speed. A true negative feedback system with little or no thermal delay between the radiator and the sensing element of the viscous unit.

Depending upon the location of your electric fans thermostat switch, I suspect that it is simply an on/off switch with no subtle temperature control and is at the mercy of the hysteresis loop involved.

Thus the position of your fan thermostat switch may need to be optimised or experimented with, to ensure there is the minimum of thermal delay between the heating effect and the urgent need of cooling.

You may be interested to read some stuff about the original RV8 cooling system as it applies to the SD1 Efi system,not necessarily a solution to your problem but never-the-less will add food for further thought.

http://www.vintagemodelairplane.com/pag ... ing01.html

Whichever god you pray to, good luck!

I'd question if the 2nd "loop" is moving too much water and thus it is "missing the Radiator" - I remember reading that MGB's had this broblem and in the summer (when the interior heater was in the off position) there was no cooling problem but in the winter when the heat was wanted in the cabin the engines overheated.

It turned out that the open flow through the heater matrix reduced the flow through the radiator enough for the engine to overheat.

Long story but easy to try to fix. On the narrow pipeheading to the rad - clamp the rubber hose with some mole grips - restricting the flow to a trickle.

Start it up and see if it helps.

Also what size is your radiator core - yes 5 cores thich but perhaps not enough cross section area. - though I doubt that if Westie sell them for the Seight

What is the fan size? and if possible did you get a CFM rating on it?

Lastly is there enough areas behind the rad for the hot air to exit or is it causing too much resistance the the air flow?

Sorry a few more questions

Ian

Also following on from Ian's reply, is all the air being forced through the radiator? is it spilling over the side of the rad and effectivley missing it?

It's also worth checking the seal and relief valve on the pressure cap - if the system is running at too low a pressure it will run hotter than it should

Agree with above and just recently there have been postings about cooling so worth a read.

A couple of points: is there really enough air getting out as mentioned above, inlet ducting will play its part, and minor point is fan switch should be on exit from rad so it knows when water is not being cooled enough (as opposed to engine just being too hot).

Otter switches will switch on at one temp and keep going until the lower setting is reached. My V8 one is Rover Part: PRC 3541 rated 96/91 degrees C - about £18.

Does it also run at 98-100degs when cruising on the motorway? or does the temp come down?

Is there anything to restrict the bypas when the thermostat opens? If not then you wont be getting full flow through the rad.

Also has the timing been setup correctly? Too retarded can cause overheating, also fuel ratio? too lean also could cause more heat.

The small bleed tube needs to run uphill all the way to the header tank. The header tank needs to be the highest point in the cooling system.

Tom.

hello,

I too i've had my V8 westfield for nearly 14 years now, and have only ever suffered over heating once.

my old 3.5 engine, ran all day at about 82-88degc, and no more than 90degc in traffic on the hotest of days.

My new 4.6 lump....the most its got up to so far was 104degc on a hot day and a long run with a 10mins on idle, but runs more like 88degc+

I've run the same cooling system/layout on both engines.

I too have the alloy V8 radiator, and this should be adequate for your needs.

I would make sure the fan comes on at a reasonable temperature, mines the standard ford switch at 82degc, with a standard SD1 thermostat also 82degc.

If you have no air locks, then as been said already timing & fuelling can add to engine temps.

scott

You should not have the connection from the back of the offy to the header tank - this is a positive pressure - the header tank should only have a connection to the pump suction and be under a negative pressure - this ensures that air and fluid is drown down the small bore pipe from the top of the rad - auto bleeding the system.

You have a full 1/2" bypass of all cooling the way it is shown.

If the outlet from the front of the offy also goes full bore to the pump return you have 2 off by passes around the rad !!

1. Remove the connection from the back of the manifold and blank it.
2. Ensure that the connection to the header is only to the inlet of the pump

The bypass from the off to the pump has a restriction in it but if the above does not solve the issues look at drilling a 4mm hole in the top of the stat and putting a restriction in the pipe between manifold and pump.


Andrew

Hi
One question that is bothering me. . how have you measured the temperature? are you gong off the gauge off the dash, or a seperate calibrated measuring device?
I think you may have an issue of far too many cores in the radiator, especially if it is not contained entirly in a duct. I suspect also that the hole at the front of the radiator at the opening of any ducting will be far to big for that many cores. If you are going to continue using that rad then restrict the size of the opening of the ducting at the front to about 50% of that of the rad area and have it open out gradually to the rad area, you will definatly have to sort out the exit ducting properly as any air that makes it through the core will be pretty much stagnent and tending to stall any further flow, you will probably need to run fans continously to clear any bach flow through the rad.
Best regards
Mike

I'll be running mine pretty much as Darkspeed/Andrew suggested. Bypass thermostat into the bottom hose just before pump where the header tank joins in and no extra connection from the manifold. I've just not decided whether to join the bypass to the header hose then use one connection in the bottom hose or have each connect to the bottom hose directly. I'm guessing the bypass should have the 'easiest' route.

FWIW I've seen some discussion on the Westfield V8 email list about using thinner radiators. I know Graham who has a 5+ltr V8 Developments engine (330+bhp) used to run the huuuuge radiator from John Eales/Docking but has swapped to a more upright thinner radiator and has no problems. He's using the standard nosecone with (as far as I know) no ducting.

Mike

Thanks chaps the comments and ideas, sorry for the late reply! I'll have a look at the car and chase a few things up and will post back here with the results.

As for some of the questions...

Ian, the fan is a Pacet and was the largest diameter and CFM rating for the space available, so should be more than up to the job. This fan is behind the radiator and is pulling the air through.

Behind the radiator is the ducting in the nose cone, so most of the hot air runs up and over the bonnet. The radiator itself is as big as will fit in the nosecone, and there is little to no room for air to simply flow around the radiator rather than through it - so that shouldn't be a problem either.

Bryan, the cap seems fine to me, and it certainly isn't leaking or running at too low a pressure. When the engine is running, the cap can safely be removed (until it gets hot), but as soon as the engine is turned off, if the cap is not on there is an enormous back surge which apparently is quite normal? It does expell quite a lot of fluid though.

SuperV8, it runs at a steady temp on the motorway, which would usually suggest an airflow issue more than anything, but of course this is when the cooling is working at its best anyway, with a fast flow of cold air through it. The main problem with the hot running is not being able to lower the temperature. If the temperature rise is "caught" early enough, the temperature can be controlled. It does not lower the temperature - it simply stops the rise, which suggests a problem or an inadequacy in the cooling system. It has never actually suffered from "classic" overheating and an overflow; it is just this hot running which is a cause for concern.

The ignition timing is one thing I will look into, as it has not been checked for a while, and there is a bit of popping back through the exhausts as well.

Cheers

Westy wrote:it runs at a steady temp on the motorway, which would usually suggest an airflow issue more than anything, but of course this is when the cooling is working at its best anyway, with a fast flow of cold air through it.

The main problem with the hot running is not being able to lower the temperature. If the temperature rise is "caught" early enough, the temperature can be controlled. It does not lower the temperature - it simply stops the rise, which suggests a problem or an inadequacy in the cooling system.

I think you have pretty much answered your own question:

# As speed the airflow is good enough to provide a stable cooling effect but not quite enough it suggests that ways have to be found to extract more heat.

# thus to get that extra heat out of the engine is going to require an even higher rate of air flow and/or a higher rate of water flow.

Regarding both the above I have to take you back to my earlier observations and suggestion - viz:

Your system design appears to be capable of maintaining a reasonably stable temperature when running at or around the 100 deg C mark and because you are simply running too hot as opposed to suffering surges of overheating then I suggest two discrete actions, designed to improve the extraction of heat from the radiator fins and/or to do it sooner.

1 Change the main fan/radiator thermostat switch to a lower temperature unit.

AND

2 Increase the air flow over the radiator fins by one of the following methods
. a) increase fan diameter
. b) increase the number of fan blades
. c) increase the pitch of the fan blades
. d) increase the fan speed

That way the "fan cooling" part of the heat transfer process - as opposed to the "ram air" part - starts a little earlier in the temperature rise cycle and with the fan running sooner your temperature may not be going to get so high.

And of course, the increased air flow speaks for itself.

Changing the fan thermostat does seem an easy option to "catch things earlier" as you suggest is needed.

OK, as you point out, some of the above is not possible, but some of it is, and will require some modification, sure, but it seems to me that if you increase the rate of air flow you do at least have a chance of solving the problem.

Increasing water flow also seems a logical approach, if it can be done, with an auxiliary/custom water pump or similar.

That issue of water flow rate may also be reviewed and addressed by looking for current restrictions in the flow of water, either by:

# undersized pipes,
# constrictions of pipes/galleries
# crud that is needing to be flushed/back flushed away.

Also you need to review if you have too many radiator cores -
adding to the possibility of restricted Air flow.

You also mentioned that there is a diversion of airflow from inside to outside of the bonnet if I read this correctly:

Behind the radiator is the ducting in the nose cone, so most of the hot air runs up and over the bonnet.

That in itself also suggests that there could be a build up of hot air awaiting to escape through the ducting.

At slow speed, what is going to encourage that slow moving hot air to get a move on?

With my old engine I had a similar problem in that my fan would struggle to bring the temp down when driving slow/in traffic. I just put it down to needing a more powerfull/more expensive elec fan.

I origanally built it with the fan pushing through the rad. I few years ago i changed it to pull through the rad but only changed the direction of the motor, I didn't realise the blades were areofoil shapped, same as an aeroplane wing. I had the flat part of the blade (high pressure side) against the rad so although the fan was pulling air through the rad it wasn't being efficient.

Due to an engine swap I have yet to use the with the blade turned over, but hoping that was a factor in the fan struggling to bring the temp down when in traffic!

So check that with your fan pulling that the curved (low pressure) side of the blade is next to the rad.

Tom.

When the engine is running, the cap can safely be removed (until it gets hot), but as soon as the engine is turned off, if the cap is not on there is an enormous back surge which apparently is quite normal? It does expell quite a lot of fluid though.

This sounds fairly reasonable. I assume that there is some release of pressure if you remove the cap while the engine is running.

The back surge may be caused by an air lock in the system - I would usually expect some back surge, but would not expect large quantities of coolant to be expelled