Track car windshield defogging - HEAT needed?

[NigelStu]

Question for those who have tracked/raced their E30s in less-than-ideal conditions: rain, cold, fog, snow, etc. Basically, I'm looking for advice based on experience here from anyone who's tracked their car and had the windshield fog.



What is the minimum required to keep your windshield fog-free?

• Is a stock blower unit blasting ambient-temp air onto the windshield enough?
• Or is heated air necessary to keep things clear?

In other words, from your experience, did you have to turn up the heat while on track to defog, or were you able to just turn on the blower?




Background on my question. My project car(s) "Thelma" (and the donor, Louise) will one-day soon become a ChumpCar. Her first event will hopefully be at Road America last weekend of March. Yes, it will be cold, and ideal conditions for fogged windows. There may even be snow....


In the interest of speed and reliability for the enduro, I want to take everything out that isn't of use (less weight PLUS less things to go wrong/break/leak). The stock blower/heater unit will remain in the car, hooked up to the DEF ducts and somehow rigged (sans dash) to be directed onto the windshield. Fog-X (or similar) will be liberally applied.


Ideally, I'd like to remove the heater core, hoses and all other unnecessary bits of the heating system and just have the blower and DEF ducting. Retrofitting a heater core/hoses after the fact and at the track is on my list of things to avoid: If heat is needed to help keep the window clear, it needs to go in now. If its not needed, I want to save the weight and give my drivers some peace of mind that the core or hoses wont burst on them.


Thanks!

[Fusion]

I would certainly check some anti-fog products. One winter the blower in my first car died and I had no heat/airflow. It wasn't much of a problem until my breath fogged it and in below temps it froze to the windshield. So I got some antifog stuff and it worked surprisingly well, though DD required application like once a week.

[KenC]

Are ChumpCar rules similar to LeMons in that you can't run any windows other than the windshield? With interior and exterior temperatures equal, you shouldn't have much trouble with foggy windows. I'd just rub some anti-fog compound on the inside and make sure your wipers are in good shape.

[NigelStu]

Chump rules requires removal of all glass other than the windshield, but allows putting plexi back in. We plan to do this for the aero aspect (Road America has some LONG straights! woot! 100+ mph in an car on stock-suspension with used parts!)

But both front windows will be down. Er, out. It'll still be a bit warmer inside the car than outside.

So, anti-fog plus blower and I should be OK?

[KenC]

Other than it being more comfortable in the snow/rain, you're not going to gain much by putting Lexan in... and that stuff's not cheap.

[jlevie]

I have a fair bit of experience in racing in the rain in a Spec E30 and a Lemons/Chump car. Trust me, you want the meanest baddest defroster you can manage to have in the car. I spent two hours in a Chump car with no defroster in heavy rain. Even with RainX on the inside of the windshield the fog was terrible. At one point I was only able to keep about an 8" diameter "port hole" (what I could reach with my glove) clear. It was like trying to drive through heavy fog, at race speeds.

I retained the defroster on the previous and current Spec E30 and would never consider not having them. Even with a working defroster you'll get some fogging in heavy rain on a cold day.

With new heater hoses, a good heater core, and a cooling system that is working the way it is supposed to the risks and weight penalty of the defroster are minimal compared to the benefit.

Something else for you to do. With all of the side and rear glass out of an E30 exhaust fumes will build up in car in heavy traffic. Add an NCAA duct to the upper corner of the left and right front doors to push air into the car and keep the fumes out. Those will also help cool the driver on a hot day.

[NigelStu]

^
I want to confirm - Are you saying the system WITH the heat? or just the blower? Like I said in the first post, the blower and DEF ducting will remain. Does the heated air make that much of a difference between a clear window and driving a foggy submarine? I'll look into costs for replacing those few components. (anyone have a known good heater core they would be willing to sell for cheap or donate to the team?)

There are multiple reasons I have to run RR windows. There will be something there.


I may add some ducting for the race at BeaveRun in July, but I don't think we're going to need any additional cooling for the March race at Road America. I'm thinking more like adding some hand warmers to my race suit for that one! :D

[SkinnyVT]

liquid soap on the inside of the window is better than any commercial anti-fog stuff, but I would echo Jim's statement of if you can have the heater going, do it.

[kishg]

you need heat to defog, cold air won't do it. if you can keep the heater keep it, else you'll need to rig up someway to get hot air into the windshield area. A common way to do it is to get heated air from the trans tunnel area and duct it along with an inline fan.

[jlevie]

^
I want to confirm - Are you saying the system WITH the heat?

With heat.

[rightcoastbias]

Ah, the little things you fail to think about until youre barreling down a straight.

[NigelStu]

Thanks guys - the build will include heated windshield.

Maybe I'll even add in a hose for warm air to the driver. Just in case its snowing. :)


Man, I can't wait for this event!

[NigelStu]

Ah, the little things you fail to think about until youre barreling down a straight.

To what are you referring?

[rightcoastbias]

To what are you referring?

Not poking fun. I am only referring to the way problems appear, especially when you begin to modify an production car outside of its intended purpose. You must re-engineering various functions.

Props for your pro-active approach.

[kishg]

Thanks guys - the build will include heated windshield.

Maybe I'll even add in a hose for warm air to the driver. Just in case its snowing. :)

link to heated windshield? driver probably doesn't need heated air in a racing suit + nomex under layers. be careful where you get the air from if you are directing it to the driver.