Plug Bug: Blower install on the motor

Electric Bug

The bug’s motor runs pretty hot on hot days. You can’t keep your hand on it for more than a brief instant. I have measured the temperature with an infrared thermometer, but of course, right now I forget the values. I know that it was well below the values for the motor’s casing temperature, but more than one person has told me that running the motor cooler will prolong its life.

So, I finally decided to install a blower. evsource has this electric motor blower kit for $448, which is quite pricey. I figured out they use a rather weak 105 CFM “squirrel cage” motor. I discovered that Jabsco makes quite a few DC blowers. They all suck because they are too loud, but I figured mine would only run when the motor was hot, so it wouldn’t be too big a deal. Most people run them all the time, since it is easier to wire up, but I hate the noise when the car is fresh and cold (and the waste of energy).

I bought a 150CFM one from on ebay for $80 (plus 15 shipping): Jabsco DC 12V 150 CFM Flexmount 3″ Blower – 36740-0000. I have a feeling it will fail in 3-4 years, since this model (actually, all the ones rated under 250 CFM) aren’t rated for continuous use. Jabsco says you can use them continuously, but they have a lower life span than their “heavy duty” blowers which are made for continuous use.

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I had some think steel flat stock laying around, so I took it cut a piece about 3.5″ wide off with the plasma cutter:

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I measured the circumference of the motor and cut it down to length; note, if you are doing this, add an extra 2″ for the tabs that will be bent at the end.

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I scribed a 3″ circle in the center and cut it out with the plasma cutter. Same goes for some holes for the terminals.

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I rolled it on the slip roll to the shape of the motor, and also made a smaller 3″ diameter one for the blower inlet:

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I flattened the bottom; this would have been easier to do before the slip roll:

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TIG welded it all together:

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Then I cleaned it up with a dremel and grinder. I used my cheap harbor freight bender to bend the ends:

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I drilled them out for 1/4″ bolts (using two).

From Amazon, I ordered some cork gasket ($15), 3″ marine hose ($10), and clamps ($10). (total cost for this project: $130, including about $15 in shipping).

The gasket I glued onto the back with some hi strength adhesive:

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and then trimmed it to fit. Oh yeah, first I had powder coated the thing sparkly red:

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I drilled and tapped a few mounting locations for the blower, and set it all up:

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The blower comes on in two ways. The first is a switch I have mounted in the cabin so I can turn it on when I want (i.e.: going up highway 17). Second is a 50 C snap switch.

(digikey.com: 317-1512-ND THERMOSTAT 50 DEG C N/O FASTON). I also bought a 60C and 70C switch, in case it comes on more often than I want.

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I’ve only driven the car a few times with it. In a cool morning, it didn’t come on at all on the way to work (the motor was cool), and on the way home it did come on and seems to vacate a lot of hot air. Awesome.

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