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Benefits of an Alternator Upgrade

This may not be that much interest to 1800 owners with engine driven cooling fans but it may well be of interest to those with an electric fan(s)/ cooling issues.

My V8 was running the standard original fitment 45 amp alternator and whilst generally adequate in most driving situations It did have a problem with the fans running slowly whilst on tickover/in traffic. Although the engine was far from overheating I was concerned with the amount of time that the fans remained on for (almost permanent until I got some speed up) and the resultant wear on the fan motors/the alternator having to work harder.

With this in mind I firstly looked at increasing the output of the standard AC Delco unit but found it wasn't possible to increase its output so i looked at alternatives and found that I could adapt a generic Ford alternator to suit the V8 and by changing the regulator increase the ampage to a massive 70amps. I don't want the extra amps for lots of lights etc but as you know an alternator is a bit like engine bhp so the maximum 70 amps isn't available until around 2,500 rpm but what it does do is give you a lot more lower down the rev range verses the original unit-50% infact so at 750 rpm I have the 35 amps that the original produced (when new) at 2,500. Well that's the theory anyway.

Before swapping them today I checked out the speed of the fans with the old alternator before replacing it with the new one and repeated the check

This first pic shows the original AC Delco 45 Amp unit

The engine speed for all of these tests was approx 600rpm

Here you can see clearly that the fan speed was 2402 rpm

Here you can see the new adapted unit-which infact has more clearance to the rocker cover than the Delco unit

And here is the result 2,600 rpm which is a healthy 200 rpm more-this actually raised to 2,800 when I raised the idle to the correct 750rpm

I am very happy with the 17% increase and in real terms it has meant that the fans spin for less time and actually (on a simulated town test in the garage with the door open) the temperature actually reduced enough for the fans to shut down for over a minute between cycles.

I have looked on eBay and can't find anyone else offering a similar item so am thinking of selling them on there-more money that the Mrs. won't find towards new projects;).

If any of you out there who have purchased the 65 amp 1800 unit on the recent GB have a meter to measure the fan's speed it would be interesting to see how much of an improvement you get

If it ain't broken don't try to fix it as if you do it will definitely break

Very interesting testing! How come you did all the testing down at 600rpm? Doing a few other bits at the same time as well or just easier for the testing?

Thanks...I had just balanced the carbs up and that just happened to be a nice smooth idle. did you notice the oil pressure is still at 50psi when warm

If it ain't broken don't try to fix it as if you do it will definitely break

Oh yeah!

Good pump and compression on that block then

That's good to know Colin, can the twin fan units be fitted to a standard 1800 engine/rad? If so, it could be a useful upgrade with the uprated alternater that maybe cheaper than the ubiquitous Kenlowe;)

Sure can phil...I wired my up slightly differently to the standard V8 system to improve the current flow plus I gave each individual fan a fuse so that if one fan was to go I would still have one left working.

If anyone is interested in how to go about it then let me know

If it ain't broken don't try to fix it as if you do it will definitely break

Cheers, I'll definately be interested when the bodywork is finished.:)