DIY Forced Air for helmet


Force air for the helmet is really cool. Pun intended. The cool air is nice, but more significant is the reduced fogging, especially if you wear glasses. Here’s how to set up force air on the cheap. Parts needed:

NASCAR brake duct blower. The Detmar 754 is a good solution. Not hard to find it for $25. Detmar 754 Blower, In-Line 3 Inch Intake X 3 Inch Exhaust, 12 Volt...

3" to 2" reducers. 1 or 2 of them, depending on whether or not you’ll be routing air to your blower, or just letting it “suck”. Here’s an example. They can be found cheaper tho. 3" to 2" Aluminum Reducer

The hose that you would stick on your helmet’s air port is about a 2" outside dia. So you can shove it inside of the 2" aperture on the reducer. I used mostly Home Depot pool hose. At the hose end I used some kind of rubber adapter that was the right dia. to connect hose to helmet.

Ultimately, here’s what you end up with…


Wht is the voltage draw? The coolshirt blower pulls my voltage down 1/2-1V which is a ton.


I’ve not personally checked how much current goes thru the fan. The site in the link says 3.5A which would be about 400W, which seems reasonable. Maybe your V meter and the blower share a common source or ground. If either was imperfect, the reading on the V meter would get skewed by the current going thru that shared element to the blower.

Our alternator puts out what, 50A? I figure that in order to genuinely lower system V, something would have to pull about that same amount.


I don’t get where you get the 400W power rating. That is almost microwave levels of power.

40Watts would be the right power for 12v and 3.5 amps.

“3” In-Line Blower

Intake Diameter: 3"

Exhaust Diameter: 3"

Length: 8"

Mounted Height: 4-3/4"

CFM Rating: 158

Rating: 12VDC 3.5A

Ignition Protected - 6 AMP Fuse"


Re. 400W. Good catch. I screwed that up by a factor of 10. Oops.

Re. Microwave levels of power. Must be some real sissy microwaves in your area .