Pre-serp bigger alternators?

[ruaricoles]

Has anyone ever fitted an alternator with more than 100A output to a pre-serp 500? Our 1994 car has a 65A Marelli job which frankly isn't really up to the job (despite being reconditioned) and given that I'm in the process of fitting some bigger cooling fans which will draw up to ~54A between them I'm thinking the bigger the alternator output the better really.

From looking in the archives it seems I can get a 100A version of the same one (an A127-100 if I remember right) but has anyone ever tried anything better still?

Thanks,

Ruari

[v8 racing]

I believe you can get 160 amp ones i will check tomorow

[toma500]

Ive got a 93 pre serp 500 and i had to get a re-conditioned unit for mine when it went on the blink , But i,m almost certain that mine was an 100 amp alternator and that was a magnetti marelli also .

[that daddy]

100A IS PLENTY BIG,90A will cover most cars easily.

[GreenV8S]

54A is a heck of a lot of current, do you really need to sustain that, or is it just the startup current?

[Aaron C. Reskew]

The serpentine alternator was designed for heavy current draw from numerous ancillaries as fitted to the Range Rover.
As was said 90 amps is sufficient.
Just check your alternator is charging properly and that the battery is in good order.

[ruaricoles]

I've got a new pair of KV6 Freelander fans which are rated to 700W, ie.~54A if running flat out at 13V. The original Griff fans are 500andsomething W I think in total. These new ones look ideal as they're mounted in a nice cowl and the total area looks much the same as the Griff rad. There are blown flaps in the cowl too, although they're not going to work by the time the thing is leant forwards in the Griff, and a big fancy PWM controller which will be replaced with a 2-stage Modwise kit. Mongoose is kindly sending me an old rad so I can mess about with the mountings and any mods required before taking any bits off my car (which is in more or less daily use).

But at 54A for the fans, say 20A for headlamps on full, 10A for the interior blower on full, a few amps for wipers/stereo etc. only leaves you 10A to run the engine and anything else even with a 100A alternator. Perhaps that's generally enough though?

Thanks for your suggestions all.

Ruari

[Aaron C. Reskew]

The standard curved vane Spal fans are excellent and draw less than 10amps each.
54 amps sounds excessive to me for any pair of fans.
I would expect to be sucked along the road with the cfm drawn from that lot.

[shpub]

You can get uprated race alternators to about 160 amps. Very expensive at around £500 IIRC. Also the alternator fuse and wiring may need replacing to cope with the higher current. The BIG fuse thingy is not suitable for anything over 100 ish AMPS and you will need a MEGA fuse replacement.

I don't understand the need for bigger fans TBH. If the engine is operating at the correct temperatures, then what's the advantage? Seems a lot of trouble for nothing.
If the engine does overheat then there is a problem somewhere with the cooling system.

[ruaricoles]

Until one of the fans packed up recently, our car was cooling fine, but it was clear that the weakest aspect of the system was idle and the high-speed cooling had plenty of spare capacity. In fact, driving from cold it often won't ever climb above 70degC (70 indicated on gauge anyway) until you get stuck in traffic when it climbs up to the 80-90degC or so where presumably it should be. The heater performance isn't great until it heats up to that level either, not so good on cold frosty mornings.... Conversely, keeping the engine colder on hot days in traffic must be good for the cabin temps too.

The biggest negative effect has to be from the lack of a fan cowl (given that the rad itself is well sealed to the body all the way round), so rather than replace the knackered fan with another standard one I thought it'd be nice to get a new pair with an incorporated cowl. And these new Freelander ones were headed for the skip at work and look about the right size so it seems a good idea to use them!

Plan is to fit one of David Beer's 2-stage kits, so with the switch-on points set properly it's highly possible that only 1 fan will ever be required most of the time, drawing less current than the 2 original fans together. The fans have a dividing wall in the cowl between them, so I shouldn't get much recirculation with one fan on and the other off. And if the alternator will cope, with both on together the car should be happy idling all day long in any temperature ever seen here or France or wherever with correspondingly lower underbonnet temps in general.

Ideal would be to have some system which would let both fans run together at half power (or even fully variable like the original ECU control) but I think that might be a little complex!

I've got the performance curves for these (Gate ones, if I remember right) and the original Spal ones and for a given power consumption they're comparable so the flow rate with them flat out should be massively improved. The blades on these new ones are also curved and they should be matched as an unequally-sized pair to be relatively quiet too.

I also want to stick a thermocouple in the top hose to see if the temp gauge indicates anything like reality.

My main question was if the alternator would cope (existing 65A one certainly won't), but it looks like 100A should be enough so hopefully I'll try one of those!

Thanks all,

Ruari

[shadowfax]

A properly running standard Griff (edit to say) 500 is the most efficient and pleasing driver's car within these isles

No need for fan-nying

Edited by shadowfax on Friday 6th October 22:28

[GreenV8S]

Check the air on temperature in front of the rad. Getting hot air recirculated through the rad absolutely knackeres cooling system performance. Remember to check under realistic conditions i.e. allowing for some ambiant wind in various directions. The standard fans deliver enough air, as long as it is cold.

[david beer]

Ideal would be to have some system which would let both fans run together at half power (or even fully variable like the original ECU control) but I think that might be a little complex!

I know its a bit naff to talk your own stuff,but, the fans will both be running at half speed for the first stage, then switch to full speed, it sounds like you will never need full speed though !!! Something doesnt have to broken to make an improvement, i know there is nothing wrong with plastic indicator stalks, standard brakes,standard shocks, crap lights, slow windows, stupid boot opening, 275 bhp from a 500, no radio reception,no locking glovebox, and sloppy drop links. Ok i made it up about the radio reception, but i think the point is, if you can improve on something, do it, i certainly will not be putting my Griff back to standard.