I have been noticing some extra heat inside the car recently. It's been pretty hot and humid here this month, but even on a cool night I can feel heat coming up from under the dash. If I put the blower on, no A/C, just the fan set to cool, it blows air slightly warmer than ambient. That's pretty normal, what I'm concerned with is the floor pans and the metal work under the dash that holds up the center stack is uncomfortably warm and radiates heat! Is this normal for modified stangs? I know tuning, tweeking, supercharging all adds to engine temps, but if this was normal it would be pretty unacceptable. Anyone else notice this in their cars?

 

I had that heat issue in my 87 GT and I now have it in my 08 GT/CS. I dont know what causes it.

 

I tell you, here in FL, there's no escaping this. With any car.

It's been warmer this year, more than usual (except on the West coast) so I say, nothing is wrong but keep an eye on things...
Check your insulator on the firewall and make sure it's tight against the sheet metal, check all grommets etc...
Also check the cabin filter area as well.

A supercharged car with get a little bit warmer as well on top, which will heat up your firewall and hood.
A turbo set up could be even worse with all the exhaust plumbing etc...

 

I did a little searching myself and it seems that it could be from the plumbing to the heater core. I am going to look under there and see if any exposed tubing can be insulated with some foam. I also read that someone had wrapped their exhaust piping under the driver seat area with header wrap and it helped insulate it from the cabin.

 

Sure, there will always be improvements to be made.
The question is, to figure out if your car puts out the normal amount of heat or is there something out of the ordinary that causes too much of it.

I have to admit that no one have posted this kind of problem with these cars, or if it was posted, I simply missed it.

Good luck.

 

Now that I have crawled under the dash it's pretty obvious where the heat is coming from. Right under the center stack is a big black plastic box. I take it this is where the heater core is located. There's 2 metal lines going into it and they are hot enough to burn your finger. The whole mass is uncomfortably hot to the touch. The fire wall insulator is working, that's only slightly warm. Looks like I'll be making some kind of side panels and insulating them to keep the heat contained. It's a bit of a stupid design really. When the temperature controls are set to cold it should close a valve to the heater core before it crosses the firewall, keeping the heat in the engine compartment. I wonder if it would be possible to put a manual valve in and just bypass the heater core in the summer. Not quite ready to tear it out completely as it does get cold here! LOL!

 

Yes, you can bypass the heater core...
It's usually done in the engine bay with a manual valve on the hoses going to the core.
It's not easy to do it aesthetically though.

 

When you do whatever you do about the problem please post it! I know that its a problem but dont have the time to play with it now!

 

I think the sun causes it

 

I would suspect an OEM heater bypass valve from years
gone by would look OEM to most.
Two inlets and two outlets.
In by-pass, the water goes into the valve from the engine
and returns directly back to the engine.
In open mode, the water goes from the engine thru the
valve into the heater core. It then returns to the engine
thru the by-pass valve.

Vacuum or 12V operation?