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Then you need a fan controller - I have yet to find a satisfactory off the shelf item. I built my own variable speed and sequencer using an Arduino the goal being soft start and load based sequence and speed, I have bench tested and it works though I've not tested it in anger yet so I'm sure theres more to learn - I have a 15 and a 12. The fans are Comex which I'm sure will raise an eyebrow or two.
Hmmm. Maybe I should stick to a 16 and 11/12. Right now I want simple so lol...
If it is have I seen these fans run the answer is yes from stopped to full load using an automotive temperature sensor or two (working out how to sequence and measure flow temperature of both banks plus radiator return), I want to see the impact of the return on the flow temperatures with the goal being to take the thermostats out of the equation so they stay fully open once hot. Primary fan is the large one, small is the backup, I need to figure the %age needed for AC performance and how to measure - may need to forego this in favour of a keep it simple solution. So yeh I guess it is complex and a bit of an experiment - have I seen them work in the car - nope it has no engine right now.
If it is have I seen these fans run the answer is yes from stopped to full load using an automotive temperature sensor or two (working out how to sequence and measure flow temperature of both banks plus radiator return), I want to see the impact of the return on the flow temperatures with the goal being to take the thermostats out of the equation so they stay fully open once hot. Primary fan is the large one, small is the backup, I need to figure the %age needed for AC performance and how to measure - may need to forego this in favour of a keep it simple solution. So yeh I guess it is complex and a bit of an experiment - have I seen them work in the car - nope it has no engine right now.
Not seen yet - but I will be - not missed anything yet been watching some of the behind the scenes interviews. It is interesting to see how the actors morph into the fantasy - although I don't really see it as fantasy, there is a 'dark side' as there are parallels with politics and society as a whole, it is also a great place to escape to.
The biggest, baddest 16" fan Spal sells will do 2,467cfm @ 26amps but isn't rated for continuous duty. Think of it for cooling down a race car.
You get more airflow with two 12" or 13" fans than one 16" fan.
The biggest, baddest 16" fan Spal sells will do 2,467cfm @ 26amps but isn't rated for continuous duty. Think of it for cooling down a race car.
You get more airflow with two 12" or 13" fans than one 16" fan.
You need two Ben, that is for sure, I was not advocating a 16 inch only. The 30102120 at 22.5 amps is I think the one I have, together with a 12 inch. With an 11 or 12 an inch they can just be squeezed into the space. Superb fans, they will cool the engine in traffic after a hot stop and you can watch the gauge dropping.
But the switching system is key to their working properly.
For a fan controller, I am a big fan of Auto Cool Guy. His fans are pulse-width modulated so they don't run full-speed until you need it to. Most fan controllers turn on and off at set temps. They run full-speed when on. If you have a 195-185 switch, the fan will turn on and run until the switch sees the coolant has dropped to 185.
With the Auto Cool Guy controller you set the temperature you want the water to flow into the engine. The PWM controller can run the fan at full speed if it needs to, or it can run the fan and (for example) 30% of full load speed if needed.
His website is tough to navigate but I think this is the one I have on my XJS.
You need two Ben, that is for sure, I was not advocating a 16 inch only. The 30102120 at 22.5 amps is I think the one I have, together with a 12 inch. With an 11 or 12 an inch they can just be squeezed into the space. Superb fans, they will cool the engine in traffic after a hot stop and you can watch the gauge dropping.
But the switching system is key to their working properly.
I think i read somewhere u have the 16 wired up to the RH side temp sensor?
For a fan controller, I am a big fan of Auto Cool Guy. His fans are pulse-width modulated so they don't run full-speed until you need it to. Most fan controllers turn on and off at set temps. They run full-speed when on. If you have a 195-185 switch, the fan will turn on and run until the switch sees the coolant has dropped to 185.
With the Auto Cool Guy controller you set the temperature you want the water to flow into the engine. The PWM controller can run the fan at full speed if it needs to, or it can run the fan and (for example) 30% of full load speed if needed.
His website is tough to navigate but I think this is the one I have on my XJS.
Very tough lol. Maybe it looks better on a computer instead of my phone lol.
I think i read somewhere u have the 16 wired up to the RH side temp sensor?
And the 12 only comes on with the a/c?
Correct: it is the Grant Francis system. The OEM temp switch triggers a 70 amp relay (you need a tough relay, mounted in the airstream above the rad). I have changed the temp switch for an on at 90 off at 85 one, as it used to cycle too much in traffic crawling otherwise. The OEM switch is 85/85. I also have a second relay operated by a cabin switch, as a backup.
My sad experience (but I have no experience of the Autocool system) is that anything non-OEM-electronic fails under the V12 hood vey quickly.
I have a smart wiring diagram I made, if you would like it.
Correct: it is the Grant Francis system. The OEM temp switch triggers a 70 amp relay (you need a tough relay, mounted in the airstream above the rad). I have changed the temp switch for an on at 90 off at 85 one, as it used to cycle too much in traffic crawling otherwise. The OEM switch is 85/85. I also have a second relay operated by a cabin switch, as a backup.
My sad experience (but I have no experience of the Autocool system) is that anything non-OEM-electronic fails under the V12 hood vey quickly.
I have a smart wiring diagram I made, if you would like it.
Yes please.
Some of the post mention cotton reels for the shroud mounts? I haven't heard that term before. Do you mean rubber insulation (like grommets)? Is there a picture of these cotton reels around?
A "cotton reel" mount is typically a rubber joint between two screw threads. Used in many automotive areas where a degree of movement is necessary or to avoid vibration fractures. You already have a number of these type of fixings in place on the XJS.
Attached the home made diagram, (ask me if it is not clear) also three photos:
Heavy duty fuse box powering the fan high current relay circuits from the firewall post;
Light duty fuse box handling the switching relay triggers and warning lights etc;
Pic of radiator showing the two heavy duty relays, A = automatic (the relay triggered by the thermo switch) S = Switch (the relay triggered by the cabin switch).
In the diagram the colours refer to the loom colours I used for these circuits. Main fan relays, one for the temp switch (S), one for the cabin switch (A). The OEM ignition-on temp switch live feed still goes to the temp switch in the inlet, but the other side of the switch goes to the main fan relay. Light duty fuses for the warning lights, trigger circuits as shown in the diagram heavy current fuses for the power circuits to the relays. The cabin-switched relay gets its trigger circuit powered from the coil 12v feed, as shown in the diagram, which goes to the relays via this fuse box.
I also attach the spec sheet for the SPAL I have fitted. This is a fantastic fan, it will hold a sheet of paper on the front of the condenser when running. It is crucial to mount the fans as close to the radiator as reasonably possible. Mine are about 3/4 inch away.
A "cotton reel" mount is typically a rubber joint between two screw threads. Used in many automotive areas where a degree of movement is necessary or to avoid vibration fractures. You already have a number of these type of fixings in place on the XJS.
Pic below of a typical example.
Cheers
Paul
Ah ok. I'll have to pick some up. Anything rubber I've found has been total degraded on this car lol.
Attached the home made diagram, (ask me if it is not clear) also three photos:
Heavy duty fuse box powering the fan high current relay circuits from the firewall post;
Light duty fuse box handling the switching relay triggers and warning lights etc;
Pic of radiator showing the two heavy duty relays, A = automatic (the relay triggered by the thermo switch) S = Switch (the relay triggered by the cabin switch).
In the diagram the colours refer to the loom colours I used for these circuits. Main fan relays, one for the temp switch (S), one for the cabin switch (A). The OEM ignition-on temp switch live feed still goes to the temp switch in the inlet, but the other side of the switch goes to the main fan relay. Light duty fuses for the warning lights, trigger circuits as shown in the diagram heavy current fuses for the power circuits to the relays. The cabin-switched relay gets its trigger circuit powered from the coil 12v feed, as shown in the diagram, which goes to the relays via this fuse box.
I also attach the spec sheet for the SPAL I have fitted. This is a fantastic fan, it will hold a sheet of paper on the front of the condenser when running. It is crucial to mount the fans as close to the radiator as reasonably possible. Mine are about 3/4 inch away.
Very helpful! I'll print it out and have a better looksie.
When you're figuring out the fan shroud and install in general consider
Do a dry install and measure the gaps around the outside of the radiators to the bodywork of the car, same on top and bottom, measure the front to back depth of the radiator pack in general - the goal is to obtain some closed cell foam to close those gaps and prevent air bypassing the radiator / condenser / oil cooler pack. Treat the space where these locate with a decent wax because water is going to get in here no matter what you do.
When locating the fan shroud do it to the bodywork of the car not the radiator - brackets off the crossmember and the top plate, again use closed cell foam as a buffer between radiator and shroud - do not put any metal frame hard up against the radiator there's a reason why the rad pack is mounted in rubber. The brush seal stuff used around doors may be an option as you can fit it to the shroud.
When designing / creating the shroud if you intend any kind of sequential control of the large and small fan make sure the air cannot pass between them - this means the shroud needs a baffle to prevent air short circuiting when one fan is not running - many systems run like this but it is poor design and not efficient especially at low speeds - don't need the fan working any harder than it needs to.
I would support the view that under the bonnet of a V12 is not the place for one of those controllers - mine will not be there - actually not entirely sure where I'll put it yet, I'm considering behind the headlight somewhere but I've a long way to go.
I am in no way contradicting you, Ben; but my own experience is that on a V12 XJS the foam baffles round the rads do more harm than good. I have run no foams for over 12 years now, and my under bonnet temps and cooling are really good. Electric fans have, in effect, their own shrouds and consequently providing they are close enough to the radiator (say 3/4 inch or so) they pull properly with minimal side-drafts.
Just my own experience, mind.
I do not use the OEM shroud as mine rotted out and at the time no new ones were available. My fans are supported by an ally square tube hung under the radiator top panel, and from studs welded to the cross member, via struts. I believe that the more air that gets into the engine bay the better, and as long as the electric fans are close enough to the radiator, all is well!
This is a snap of the prototype system (before my Pacets gave up and were replaced by SPALS) which is now more smart and productionised; but it gives you an idea of what i did. This arrangement allows the distance between fans and rad to be set quite exactly.
And this shot shows the fans in the car: Fans in car, the top ally square tube is bolted to the radtop panel, via rubber mountings. This shows how the 90 degree fittings for the SPALs slot into the fan surround. WARNING: they get pulled out by the fans, so once you are OK with the fitment, epoxy them in! See next snaps: 90 degree fitting slots into the fan surround BUT see next photo: The fitting needs to be epoxied into the slot in the surround, once you are happy with the system. I also added a screw to make it even more secure.
Last edited by Greg in France; 06-02-2022 at 08:29 AM.
06-01-2022, 05:41 AM
