It's been discussed in the past. HRP https://www.jalopyjournal.com/forum/threads/make-a-cool-looking-heater-work.1067396/#post-12114706
A computer fan is too small and doesn't move enough volume of air to work as a heater blower fan. Ask me how I know that.
The fan I have now that just died is only 4 blades and fan is only about 5" in diameter. It's some kind of old small heater
I adapted a squirrel cage fan and motor from a late model into the Stewart Warner heater on our 38 Chev, I had to cut a hole in the heater body for about an inch of motor that protruded.....but it works way better than the four blade that was there.
NAPA used to have a source to order a heater motor pretty much to your spec, there were 50 motors to choose from (something probably not available anymore, but would be worth checking). I found the biggest issue is getting the blades/cage off the motor without killing it. The old heater box I have has a motor with 2 parts in the housing, one section had a small cage, and the other section had a 4 blade fan. The motor has bad wiring, and the supposed replacement motor has the wrong shaft size. Then I discovered that box wouldn't fit in my truck! I'm adapting a modern blower motor to my homemade heater box that will contain just some ducting and a core. Will have a 2 speed fan forcing air through the defroster, with or without floor heat, a coolant flow valve to control the temp, and a way to shut it off completely. Gene
I believe I have another fan motor here somewhere. Just thought maybe o computer fan would blow more air. Some of them are about 5-6” with 7 blades and 3000 rpm. Just wondered if anyone is using one. They come in 12 volt dc
Posted this before, maybe this will help. https://www.jalopyjournal.com/forum...with-with-a-7-spal-fan.1015736/#post-11478029
There are different sizes and outputs of computer fans....I'm sure one of the bigger ones should work. Not real sure, but there are some with cooling coils for the high power gaming computers,wonder if those could be plumbed to the cooling system to make a heater
I would think a pc fan would be better than nothing. It would depend if you were trying to warm up a coupe or a sedan.
I'm using one, about 4". It works good but I made my own tube and fin heat exchanger that is a lot less restrictive than a regular heater core. Gary