Wow. I think this power level is way too high. I added twin electric fans to my XJS a few years ago. A stock set up on a 6 cylinder Aussie Ford. Each fan runs on a 25 amp fuse and the set up has plenty of excess airflow. At 12 volts that’s 300 watts each so 600 watts of cooling power to move a hell of a lot of air thru the radiator at standstill.
30% of the V12’s 300 HP is 90 horsepower…that is a large industrial fan no matter which way it is configured…ball park numbers…10 cubic metres/sec at 5000 pascals…(21,000 cfm at about 1psi) that’s the sort of fan you would use on a moderate sized industrial dust extraction system!!!..I suspect that the single Vee belt drive would be shredded transmitting even 10% of that value.
I think these power saving claims of converting to electric fans are grossly overstated…
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Their numbers don’t lie, Mark - but I still believe more in other numbers presented…
Frank
xj6 85 Sov Europe (UK/NZ)
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Yes…They are definitely quieter than the large whirling mechanical fan on cold start up…when a fan is actually not needed. And as you say…at speed when more power is required from the engine there is sufficient airflow and water flow to keep the engine cool. The tricky time for the v12 is at idle when it is not producing much power but has low water flow rate thru the radiator. So the electric fans increase the radiator ability to reject heat by increasing the air flow thru the fins. One of my 300 watt fans deals with this situation very well. My XJS is managed by a megasquirt and I can watch the coolant temperature drop in real,time when the fan comes on…very satisfying to watch…
One thing to consider is electrical load. Some e-fans draw lots of current.
The old Series III 4.2s (and I strongly suspect Series II as well) came with a 65 amp alternator, or thereabouts, which, under certain conditions, was barely enough output before adding on any high load accessories.
Obviously e-fans won’t be running at all times but, still, it’s not hard to imagine a stack-up of loads that would tax the system. Think headlights, compressor clutch, blower motors, and e-fan all operating at the same time.
Cheers
DD
Let me start off by saying my CoolCat fan was an amazing piece of kit, and worked far better than the original beanie fan: that said, at idle, my 80 amp GM alternator went from 13.9 v, at idle, to 12.9, at idle, when the fan was on.
Correction to my post. I kept wondering where the percentage was coming from. So I re read my post; and well my apologies. It’s not a percentage is was total gain or loss depending on how you look at it.
A standard VC fan OE style consumed 30 HP which still seems incredible.
Sorry Gentlemen. I’m not sure why I put the % in behind the HP number.
There’s a previous post on this that I did last fall on this topic where other posters did see the video. Wiggles stated “The numbers don’t lie” on one of his posts, so I’m not making this up.
That link to engine masters worked. Looks like Motor Trend (on their YouTube channel) took their toys and went home. Bratty (Motor Trend) kids!
Cheers!
Mark
Also, in these “comparisons” need to consider the alternator as mechanical load. Electrical power (watts) calculations are output calculations - mechanically the engine still has to turn the belts and pulleys and the alternator itself. All mechanical loads. The test on the video is by process measuring all of these. A proper comparison would do the same for an electric fan. The characteristic would be “flatter” than the mechanical fan as the output would not vary. Paul
I know an engineer who races Jags, …he has electric fans, water pump, no dizzy, coil over plug, and from what I have read elsewhere, the USEFUL gain, for a road car, can be as little as 3-5HP…(except under a few limited circumstances)
(assuming the alt will use an additional 1HP MAX)
at roadspeed, the VC is “slipping” AND the airflow over it greatly reduces blade drag…ie to ~5HP
a situation where HP WOULD be improved, is take off from line, no airflow over blades and clutch fully engaged…at that MOMENT 30HP would be more realistic
Having said that, many people in Oz use the Ford AU-BA twin electrics in their Jag. Clearly Ford thought they were worthwhile
Aristides
What was the updated black mechanical fan you used?
I’m trying to hold onto the mechanical for similar motives, though an upgrade would be nice.
Not feeling the later s3 plastic fan to be honest…
Thank you.
Kind regards
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I still don’t believe that any car manufacturer would accept such useless drag, Tony…
Apart from the power loss, it would seriously affect fuel economy - neither of which may influence US manufacturers, but in Europe it would raise eyebrows.
And 30 hp is 22000 watts, as David mentions - or roughly 1800 amps at 12V. Which would certainly encourage anyone to fit 300W electrics…
Frank
xj6 85 Sov Europe (UK/NZ)
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Demian,
Jaguar at some point replaced the Yellow Fan with a new type which was Black, different material so it doesn’t get brittle, then crack, and then brake, doing some very creative work on your bonnet…
The same Fan was fitted also on the Range Rover P38 and it’s a direct replacement, (different VC though).
I had both cars and noticed that they looked very similar, and indeed they were identical!
I got mine new from Britcar (no affiliation) for a fraction of the price of the Jaguar ones. Works very very well.
Mind you I have a V12 and it had the Yellow Fan, cracked and all, but I would imagine that the 6 cyl. Fan would be the same ?
Best,
Aristides
I see.
Thanks for taking time.
Hell with it…
I’ll stick with my original metal one for now…ain’t nowhere near “modifications” phase yet.
Those are luxury problems for me right now…
After cleaning this block out it should run without cooling issues for heaven’s sake.
there is ( at least one) important demarcation point, which took place around end of S1 XJ
The early VC is the fluid type,(smooth front)… after that the “spring in the front” type
The newer ones often wont retrofit into earlier models, (without issues)…not quite enough space to radiator
the early ones are virtually unobtainable (last time I looked)…although many sellers claim they are the same…they are not.
luckily I have a few good used OEM spares, otherwise I would just fit electrics
The “smooth” one, I expect, just works on viscous friction? It doesn’t have the coil operated valving common in Toyota 4WD’s and similar? My smooth one got to a point where it was just freewheeling. I was able to locate a particularly shallow Davies Craig aftermarket fan coupling of the coil/valve type. I was quoted about $300 to recondition my original - the Davies Craig cost less than $150. I believe it to be the better option given I have only the mechanical fan and air conditioning. Works really well. Happy to be educated if the smooth one is smarter than I believe. Paul
I dont think the old style VC is better, only that I had pulled a few off S1 or 420G motors, they fit S-type,420, MKX, 420G, early S1 XJ, some where worn out, but I have a couple of very good ones
It is interesting you found an aftermarket coupler, did it have the fan attached?, and did you have to re-drill mounting holes? (balance)
a bad one will have the following characteristics;
any freeplay in blades, any notchiness, spins more than twice
a good one, spins between one and two times, is perfectly sooth to rotate. also I have noticed is silent on start for about 2 secs, then you can hear it
The smooth type (non-thermal) is designed to stay engaged until xxx-engine rpm is reached, at which point it allows slippage.
The thermal clutch, with the little coiled spring, is temperature sensitive. It slips until xxx-temperature is reached, at which point the internal valve opens (or it is ‘closes’?) and the clutch engages.
Cheers
DD
one stated test for an ok “heat sensitive” VC is to insert a rolled up newspaper when cold…that should stop it…too bad if its “not ok”
I’ve had a fan come apart on my Series III fortunately it was in the drive way, I was letting the car warm up while I was running in and out of the house looking for the stuff I forgot on my previous trip in the house. It’s a standing joke with the kids when I’d take them to school in the AM. My daughter caught on and grabbed the stuff I usually forgot. I digress…
Anyway lucky for me the fan shroud took the brunt, made a hell of a noise and scared the SH@$ out of me at the time. Anyway easy fix, I had an extra. Oh, BTW the fan is available on amazon and rockauto in yet another color - white.
I fitted my original steel XJ6 fan - provided holes lined up as if made for it. I will post a photo tonight in case any are interested. Also see if I can find a model number. Paul
