heater booster fan how much cfm?

[reluctantartist]

I had to retrofit a bus heater fan on to my 412 and while going over it to get it ready for winter, I noticed there did not seem to be much air flow so I checked it at the heater hose where it is attached to the engine tin and still didn't feel too much air. How much air should be flowing through this? Are the van heater fans reverse airflow from the 412?
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1982 Westy, 1974 412 Variant... Yes, Aircooled's are great! Oh and I do have modern computer controlled vehicles too, but I just don't care about them.

[raygreenwood]

The 411 and 412 variant have reversed airflow from the sedans....and only one outlet.. from memory....the bus fan has an inlet and two outlets like the sedan,so its possible its rversed from what you need. I have not been able to find a cfm rating either in my books or the "without guesswork" book. Ray

[Lars S]

I cant find the cfm figure either.
Also cfm at free blowing (no hoses attached) and cfm installed are two different figures due to the pressure drop in the ducting. My experience is that the 411/412 heater fan has a lot of air when free blowing but the airflow in the coupe is rather low when car at idle and heater fan running. Even at cruising the air flow is rather low to my opinion. This might be due to pressure drop and air lekage.

If you suspect the fan to be faulty you could measure the current draw it is rated at 8-9Amps at 13Volts and fan installed and car on idle.
Dont know for sure if the Bus fan is the same.
Edit: a bus heater manual states 6-7 Amps for a double outlet fan at engine running and 6,8-7,2 for a single outlet fan engine not running....there might be more bus fan types than two however...


/Lars S
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Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[reluctantartist]

Well i figured out the bus blower goes the wrong direction. So does anyone know of alternatives? I am reluctant to get another 412 fan since they are ancient so it would be nice to find a newer one to replace it.
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1982 Westy, 1974 412 Variant... Yes, Aircooled's are great! Oh and I do have modern computer controlled vehicles too, but I just don't care about them.

[raygreenwood]