924Board.org

[Patrick]

hey guys!
I dont have my oem alternator on my 79 NA 924, so no cooling shroud either. What i have is another Bosch alternator without provision for a cooling shroud. But i do have the plastic funnel like air intake.

Given : 1)I live in the tropics (very hot)
2) Usually heavy traffic (so less ram air effect for the air intake)

Question : Will it still benefit my alternator to try to have a (crude) shroud of sorts made for the rear of my alternator to hook up to a hose leading to my air intake? Or will the lack of ram air to the intake combined with the tropical temperatures make the alternator even hotter, since the shroud would totally enclose the rear vents thus preventing the escape of heat through the vents.

Anyone done this? I used the search function on 924.org and all the posts discussed the oem setup. Thank You!
patrick
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1979 924 U.S. version
Single sidedraft Weber 40

[!tom]

The primary purpose of the ducting for the alternator is to provide a cool source of air for alternator cooling, rather than a ram air source for air flow.

The fan on the front of the alternator is designed to pull air through the alternator for cooling. With the shroud and intake in place, it is supposed to be drawing air from the front of the car through the alternator, rather than drawing air from around the exhaust manifold through the alternator.

I believe the cooling ducting for the alternator is intended more for stop and go driving, rather than any benefit from ram air cooling.
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78 924 NA
5-lug

[MikeJinCO]

I would think that in your hot climate any kind of shielding around the alternator would help protect it from the heat of the exhaust header. The starter heat shield is just bent sheet metal. I fabricated one from some 26 ga. metal heat duct and put some self of the shiny aluminum duct tape on the header side to help reflect heat. Then get as much fresh air around there as you can. I got the old heat riser flexible tubing that US cars used for many years. TXJAKE has something in the how to section on using some cooling water tubing that fits perfectly.

With the proper shroud and ducting the fan probably does pull a little fresh air although, an inefficient flat blade fan like it has and with the high pressure loss of any flexible ducting it probably doesn't pull much air at idle, but every little bit helps.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[Patrick]

ITOM- All this time i thought all alternator fans were pushers, and that cooling air being pushed inside the cooling duct would counteract this . This supposed contradiction of airflow confused me (not anymore). Also we do get stop and go driving, just that on bad days its more stop than go. Thanks for clearing up the airflow direction for me!

MikeJinCO- You make a good point about its heat shielding function if lined with a suitable insulator. I never thought about air restrictions with flexible ducting though, i will have to study this aspect more before i proceed with a homemade shroud. Thanks for mentioning that.
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1979 924 U.S. version
Single sidedraft Weber 40