I think I figured it out. Of particular significance, it's been 11 months since my last post above. That's worth noting because I washed the car today for the first time in probably a year. No joke. (The dirt hides the bad paint. More on that in a moment.) It's 70 degrees out. Warm but by no means hot. Any time I sprayed water on a horizontal surface, it steamed like I've never seen from any of my previous cars, even the black one. After a few minutes, I could spray the same spot and it would steam quite a bit again.

That got me thinking back to this "warm cabin" thread. My hunch is, the SC interiors run so hot because of the thick sheet metal used in these luxurious builds. That metal absorbs a ton of heat, presumably turning everything inside it into an oven. That's probably also why the center air vents are so prone to cracking from rapid hot/cold cycles when running the HVAC in auto mode.

I had been on the fence whether to get the windows re-tinted, after having removed the awful purple, bubbled tint that came with the car. I was starting to lean toward doing so, but now I'm thinking it won't have as much impact as originally assumed. I don't like the idea of reduced visibility (I had considered clear tint, though), so I would only do it for heat levels.

Back to the bad paint... A full re-paint is the final pressing project, having gotten almost all the functional and cosmetic stuff done. But, I'm really not someone who takes pride in a shiny paint job and regular cleaning. I'd just assume hose the wheels off and go months without a full wash. So, one of the ideas I've tossed around is doing away with paint altogether and just clear coating it. A $5 can of clear should be sufficient to avoid rust. And in the interest of extreme weight savings, that would be a 15-20 lb reduction.

However, I need to tackle some dents and previously repaired rust bubbles, so I wouldn't have the cleanest, most consistent surface to clear. On the other hand, rock chip worries would be a think of the past, because you can also respray some clear with no difficult paint blending. Another unpleasant aspect would be the non-metal bits: front and rear bumpers, side mirrors, and rear valances. Plus side skirts when I add them. I know how not fun it is to strip bumpers, and they wouldn't look good as bare polywhatever with the inevitable spider cracks.

 

my gold aluminum shift **** it hotter than the sun.

 

Bare metal in a SC interior is cruel and unusual punishment!

Oh, I forgot to mention, one advantage to the no-paint idea is a much lighter and more reflective color, which hopefully would lessen some of the oven effect.

 

alpine white would be great!!

 

I would agree if not for disliking white cars in general and it being a terrible color for people who don't enjoy washing their cars regularly.

While going out to grab the mail and thinking how lovely of a day it is, it occurred to me I should start logging some cabin warmth data, to see how much it increases on warm days and potentially how much it improves with paint or tint. So, here's the first entry: 115.5° @ 63° outside air temp (OAT)! Most of the day has been in the mid- to low-50s, so hardly a scorcher.

 

Dark colors absorb more heat than lighter colors, lighter colors reflect light. Bubbles tend to spread more heat even over there surface, while boxes tend to be less efficient ,usually only heating one side @ a time, with the cool side dissipating heat. So with a dark color @ the bubble shape of the SC roof , you end up with the perfect oven. Remember AMC Pacers? They were the perfect bubble car, & you could cook bread in them.

 

Interesting theory, but pretty much every oven or microwave I've ever seen is rectangular. The only exceptions I can think of are old stone kiln type setups, and that's probably just a limitation of construction techniques. That's not to say your theory doesn't hold water, though. It just isn't particularly intuitive. Sure, the rectangle has more surface area to dissipate heat, but it also has more surface area to absorb heat.

No argument about dark vs light, colors, though.

And thankfully, I've never been in an AMC Pacer.

 

MIcrowaves use a whole different technology & not ultra violet rays from the sun.

 

I laughed out loud at work when I read that.. It's so true, my Acura had a metal 6 speed **** and I remember I used to keep an infant sock as a shift **** cover in the summer time, I got so used to it I never took it off again lol..

 

Yes, just make sure you get the correct UV film and try to keep the tint level at about 50% or less and you'll never notice at night or be hassled by anyone. Not that it matters, they couldn't fit the little measuring tool over the A pillar anyway. Having UV protection on all windows is a HUGE difference on interior temperatures.

Holy crap that's hot for a mild day. I grew up in Seattle and remember it getting to 80-90 and people would freak out. Now in Missouri, well over 100 is no problem in the summer, not having A/C or tint is not an option here..

 

I thought we were talking about shapes, not heat sources... Surely there's more to your theory than round shapes (bubbles) being more absorbent of heat from round sources (the sun)?

Yeah, there's overly warm and then there's comically ridiculous. You can imagine how painful it was last summer when I was trying to diagnose the source of my cold air being heated 20-30 degrees! Boy was that a relief when I determined it to be the HCV actuator.

I noticed today that the roof gets significantly hotter to the touch than any other body panel, be it horizontal or vertical. I'm not sure if that means the windows are letting a lot of heat in and some of it radiates through the roof, or if the roof absorbs that much more heat than the rest of the sheet metal and that in turn cooks the cabin. If anyone has a laser thermometer for measuring surface temps, I'd be curious to hear what numbers you get.

So true. Anything that warm gets multiple weather reports on the nightly news, along with a catchy heat wave title.

 

Must've been asleep that day in thermal dynamics class, or Prof Og forgot to write it on the cave wall. LOL! Never mind, supposed to be an 80deg day this week, I'll take my thermal gun & shoot my car & give you some numbers. It's dark blue & I'll shoot a white car also for reference. Also with the depletion of the protective ozone layer the suns ultra violet rays are much more intense now days. Use your sun screen.

 

I do not notice any amount of excessive heat inside the car, even with the 90+ deg weather we've been experiencing here in SoCal. But I do have ceramic tint that blocks both UV and IR light on all the windows except the front windshield, and my car is white. I used to park my car outside during work hours and temps used to get up to 100+, still it never really got uncomfortably hot. I do also use the custom fit sunshade up front when it's parked outside for several hours.

 

I've been discussing it with an engineer, in addition to my own research on various paint colors vs. bare metal, and it keeps coming back to window tint being most likely to make a difference. Sigh. I guess I need to head back to the tint shop and see if they'll let me look at their tint levels in varying lighting to decide if it'll drive me crazy in terms of visibility.

 

thermotec 14120. I emailed them a question about it cause my 5 speed swap made my trans tunnel way hotter than automatic, I wanted to find a remedy. i'll try and post the email.

me: What is the best mad to choose from for transmission tunnel. I get a lot of heat now that I swapped over to manual transmission and have a little heat going into the cabin.

thermotec: Hello Christian,

Thanks for contacting Thermo Tec for your heat management needs.
You have two methods of insulating your tunnel. You can install our Mylar Muffler/CAT Heat Shield #16500 on the underside of your tunnel to reflect heat away from this area. You may also consider installing Thermo Guard FR inside your vehicle over top you tunnel for added heat protection. Here are the links to these products for your review:

http://www.thermotec.com/products/16...at-shield.html

http://www.thermotec.com/products/14...-guard-fr.html

http://www.thermotec.com/products/12...-adhesive.html

Good luck with your project and enjoy the Ride!

Regards,

Rich Yox
Thermo-Tec Automotive Products
www.thermotec.com

800-274-8437 toll free
419-962-4556 outside the US
419-962-4013 fax