924Board.org

[bruni]

KISS comes to mind, the idea was to free up a few extra HP when when you demand full power. If you are looking for fuel economy you might consider having an open circuit except when braking, coasting or stationary, however I,m not sure that on the average journey the alternator would operate long enough to charge the battery OK if you live or work at the top of a mountain pass
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1982 931
1975 harley sportster

[ideola]

On my track car, I'm planning to go with an axle-driven alt like in the factory D-Prods. May be somewhat problematic for stop-and-go driving, but a good strong battery and good cruising or track driving should be fine.
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erstwhile owner of just about every 924 variant ever made

[bruni]

Number 4 was going to be electric water pump which is another ancillary sapping power, then I saw the thread for the "$25 sun roof" and it all came back to me, all those power enhancing decals and paint jobs available in the 1970s before EFI, ECUs I'm thinking of matt black bonnet (hood) good for 5hp minimum, go faster stripes, sun-strips and for you hard core types out there a white square on the door with a crossed out number, happy days
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1982 931
1975 harley sportster

[ideola]

Not exactly an inexpensive alternative, and more difficult to execute (i.e. control) on a non-ECU'd car. I've found two decent altneratives in my searching, and both cost nearly USD$300 new for the pump alone. They can also creates issues with in cabin heat and thermostatic control. Worthwhile on a track car, but I'm not sure it makes sense for a daily driver, especially given the lifespan rating of the electric pumps.
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erstwhile owner of just about every 924 variant ever made

[Vince Ponz]

Lighten the car as much as possible..................cost nothing
Go on a diet....................................................cost nothing
Divorce wife....................................................give her everything
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

[Martijnus]

Been thinking about that alternator stuff... if you brake, your alternator should go on... for more braking power too
I think MS can handle all that stuff...
and only charge below 11V or whatever (when not cranking)
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"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

[tuurbo]

I think MS can handle all that stuff...

I think my boost switch can do it for me! I just want that alternator to come off with the onset of boost. My MSD Digital 6 has outputs that (I think) can send current to other devices.

My problem is I don't know what to do with current I get from a boost switch or current I get from the MSD.

So electricity isn't my strong suit - if my boost switch has power running through it, how to I convert that current, or whatever, into signal the alternator understands? Like, if the power coming off to charge the battery has current, I can't see how sending that wire more current is going to shut down the alternator. So I'll need some kind of switch that interrupts current to the battery? Is my head on straight here?
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

[bruni]

Number 4 electric water pump

[ideola]

The biggest challenge is finding a motor suitable for continuous duty, which would be required for a street-driven car. There are a couple on the market under $100 sold by the big race shops, but none of them are rated for continuous duty. You really need an industrial strength motor that can withstand continuous operation while enduring the under-bonnet heat. Most of the motors that fit that description are close to $200. Just doesn't seem worthwhile to me on street driven car.

On a track car, totally makes sense, but in my case I'm going with a Davies Craig setup, which I will control from my ECU. The integral pump seems to be a better way to go, as they have been tested for these type of applications, and at ~$270 seems to be the best option. The challenge on a street car, as I've pointed out, is that the ideal setup eliminates the thermostat, and may not provide enough flow to also accommodate the heater core. Of course, a secondary could be added, but that just adds more cost and complexity.
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erstwhile owner of just about every 924 variant ever made