I've been considering fabricating my own defroster system for my HPDE car. Right now I've maintained the oem fan in the passenger area, with the accordion duct over to the oem HVAC stack that contains the heater core. I've eliminated the air vent ducts that go to the eyeball vents but have maintained the window vents.

I could theoretically remove all of this and just ride bareback without the defroster but it's nice to have. In addition it's nice to be able to blow air into the footwells to get some circulation going to and from the track.

I've considered trying to fabricate my own defroster system using some dc fans, but I have concerns about the heater core providing constant radiant heat to the passenger compartment without he oem HVAC stack in place.

So, lets discuss custom track HVAC systems. This mostly applies to heat/defrost, although I'm interested to hear if anyone has maintained a motorsports style AC. Interestingly enough ACO/IMSA/TUSC/ALMS/WTSC all require a maximum temperature in the cockpit which iirc is 85 degrees or there abouts. This is mostly because they all run closed windowed cars, but it did make me wonder about doing a motorsports style AC. How cool would that be... heh, get it?

 

I plan on installing a rear defog from an E30 'vert. The only ducting will be the Y piece that runs from the center heater box to the 2 vents that go to the windshield. Right now I just have a 12v clip on fan aimed at the windshield (no dash in the car). It works.....eventually.

Rear Window Blower Defrost Fan Heater 64231376849 BMW E30 318 325 Convertible | eBay

 

is that an electric heater in that unit?

 

There is, local guy is using it for his track car. Said he got a 30* temp rise on his test bench.

 

On my 99 I installed a condenser/fans/shroud/ducting in the trunk of the car, new a/c lines, and a tank in the passengers side floorboard for the water to drip in from the evaporator. Stock everything else regarding the a/c system. A/C performance is actually better than stock, 40*F out the vents on 100*F day in Houston at idle in traffic. Works great at the track too, it SUCKED baking in the car without a/c before.

 

This is the only truly proper way to do it. And really only requires a couple custom A/C lines, fittings, and condenser mount.

Pat, did you do a write up on this ever?

 

I never did a write up, but I did post a few pics in my build thread. I probably should do a write up though now that it's all done and proven to work. It's been installed since around April of last year I believe.

I will say it's a lot more work than I thought it would be, a bit ambitious for a DIY project. But if you want track a/c, this works. And surprises the hell out of people at the track too.

 

With my track car, because of the cage, the upper half of the heater box is gone. I am thinking of putting round vents that I can point just in the top of the dash, ala old Ferrari's have. And flex duct them to the side outlets on the box. I am kicking this down the road, but have it in the back of my head.

 

I am also planning to run the bimmer blower using the factory defrost ducting. For the worst summer months I am going to do either a DIY coolsuit or maybe a coolseat foam insert.

 

I've always thought this seemed like the easiest solution for defrost. Bimmerworld sells a very similar looking kit which they use on their pro race cars.

Defroster Repair and Replacement News - Frost Fighter

 

Remembered something about Crusher a while back and found it back for you

https://www.miataturbo.net/race-prep...e6/#post793524

 

so my set up might seem pretty ghetto to some but it works very well for my application.

so i removed the oem fan and box that contains the heater core.

placed the oem heater core into an ammo can i got from work and used self expanding foam to fill and voids in the ammo can. Plummed a 3 inch inlet into the back and a 2 inch outlet from the front of the can. used some rated coolant hose and plumbed the heater core that is in the box.

placed a 12v 3 inch bilge exhaust fan inline on a switch and some extra ducting i got from the helicopters from work and routed them up to the defrost outlets on the dash.

i can take some pictures and explain everything if anyone is interested in my set up.

 

I have one of these Demon Tweeks Micro Heater, uninstalled so I cannot comment on performance. It is tiny, but I am optimistic that it will work well enough purely as a screen demister, if not, I have another that is about 50% larger capacity. Bought it after crewing on a car at a 300km event run entirely in the wet, and realising that hoping for fine weather does not make it so.

I need to reconfigure my coolant reroute to accommodate it, but the head is about to come off for other reasons, so it will happen then.

 

I'm going to be trying out this setup in the next couple of weeks. Getting the stock defrost ducting to play nice with the cage, stock dash bar, and dash isn't going too well.

 

I am planning to dig into this on my car soon. Follow up post- I never need to worry about ice on my car, only defogging. Does anyone have experience trying to run an unheated blower through stock defrost vents? Is that likely to remove condensation effectively?

 

Found out a couple weeks ago that one of my friends has the bimmerworld kit on his GTS2 E36. He loves it and is planning to add a frostfighter kit to his new miata. After talking to him I think I'm also going to do the frostfighter kit on the lexan window in my CCP hardtop.

 

were you talking about this kit?

BimmerWorld Front Windshield Defroster Kit

 

Yep