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Discussion Starter #1 (Edited)
I'm starting this thread to brainstorm and think out loud about my plans to address the heat issues in my 84 GTV6 3 Liter

Background:
1) My windows/rear hatch are tinted with 3M Ceramic Series film. Devastating in blocking out infrared heat from sun, and radiant heat in general...with the exception of the windshield which isn't filmed. Therein lies a major culprit. I can use film from 3M or Huper Optiks that's as clear (60-70) as most new car windshields while blocking out at at least 50% of the infrared and outside radiant heat. Problem is I have a 4 inch crack near the base. I'm told advanced ceramic films reflect a lot of infrared heat,but also absorb a lot which will heat the glass and fracture it. The fix is a crack-less windshield $$. However, it isn't an issue when not driving towards the sun (or at night, which I know is redundant!)

2) I installed a Vintage Air Gen II Mini a/c system. However, in trying to keep an original look I've experienced routing and venting/output issues (little output from the center vents) which causes coil freeze up (i.e. warm air and reduced fan output). I have a plan to have the routing redone, But when it works the car feels modern. However, heat soak from engine/exhaust negates a lot of the output even before the coil freezes over.

3) Speaking of heat soak..oppressive! Heat through the glass (except the windshield) is a non-issue. Conductive heat through the floor and firewall (despite double layers of this: EZ Cool Automotive Insulation heat barrier and noise reduction for cars, trucks, classic cars, street rods and much more) and convection heat through the tunnel and openings in the firewall for steering, a/c, pedals, etc) is THE problem. Ex: If I slide the shift boot down (after driving around for at least an hour on an 80 degree day) time I can only hold my fingers on the metal lever for 3-4 seconds before recoiling. No, I don't drive that way...but it's indicative of the overall heat from the engine/exhaust/convertor that's making its way into the car. Ex: I can feel a faint very warm breeze from below the dash after quick starts from a stoplight. Ex: Same quick starts, or even stop and go movement in traffic with windows down sucks in hot blasts into the ****pit from under the car! Nothing like 120+degree blasts on a 80 degree day with the sunroof open!

So, one obvious issue is to plug or reduce as much as possible firewall openings. In addition I'm researching heat barriers, heat shields, heat insulators from DEI, Thermo Tech, Heat Shield Products, etc. Lots of products, avenues of approaches, and ideals in blocking heat from the headers, downpipes, firewall, and the convertor.

But let me start with....headers! I've attached photos of the headers on the car when I bought it 8 years ago. Can someone tell me who made them? I'm 1) debating keeping them or reverting back to the original GTV6 manifold and 2) looking into the pros/cons of wraps (DEI Titanium) or ceramic coatings (Jet Coat or Swaintech) in reducing heat
 

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Ceramic coat the entire exhaust system so the heat will be dumped out the back rather than radiated along the length of the system!

That's my plan, but I haven't done it yet.

I did ceramic coat the part of the exhaust that wraps around the rear brake rotor on my old black GTV6, and it did seem to help a lot with preventing rear brake fade. Current car will get vented rotors in back in addition to the full ceramic coating on the CSC stainless exhaust.
 

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Would you mind elaborating on your Vintage Air installation ? Maybe start a new thread ? I am planning on doing the same thing, and any information you can provide would be very helpful.
 

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When I fully rebuilt my 83 GTV I went to great lengths to reduce the in cabin heat. The main aspects involved the best UV tinting I could get. Making sure the firewall was completely sealed. It's amazing how many holes I had to plug but I couldn't see most of them till the engine was out.

Then I covered the floor and inner surface of the firewall with Dynamat followed by Dynapad. This worked perfectly. Even after runs on a track on a hot day the tunnel stays perfectly cool. The only issues are cost (it gets expensive to do the job properly) and weight. Dynapad is especially heavy plus it is an open cell foam product so will absorb water if you have leaks. In hindsight I would have replaced some of the Dynapad with Dynaliner, a third product by the same company. Liner is a closed cell self-adhesive foam that blocks heat and noise. However I would have retained the Pad over the tunnel and inner firewall.

To a lesser degree, the new door and window rubbers helped as well but more so as noise suppression.

Finally, as I installed a TS motor, I used the more modern compressor and also use Hydrocarbons as I get better efficiency out of the A/C systems.
 

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Discussion Starter #5 (Edited)
Rex and Perth, Thanks for the replies! AlfaFan, I'll do a separate thread regarding the Vintage Air installed.

Here' my game plan..but I'll start with this. I ran errands and visited friends today in/about the Hollywood area of Los Angles. Beautiful day, mostly sunny, blue sky after early morning mist and cloud cover. Passenger windows and sunroof open. Both my digital thermometer and turkey testing-style analog thermometers registered 101-102F in the cabin. However, the hourly temperatures for the time and exact areas I was in were only 76-77F! I got home about 3pm, parked in the shade, and closed up the car. Interior temp was 97/outside temp was 75. At 5pm interior temp was 90/outside temp 73. Headers, downpipes, convertor and muffler make the car a heat sink

The plan
1. Install ceramic coated (Swaintec) original 3L exhaust manifold.
2. Wrap original front exhaust (manifold junction to connection to the convertor) with DEI Titanium wrap
3. Install a combined heat shield and heat barrier over both the convertor and center muffler.
4. I'll evaluate for a for a while before adding a combined heat shield and insulator [URL="www.heatshieldproducts.com/automotive/exhaust-heat-shield-insulation/heatshield-armor"] on the remaining exhaust under the car, or supplement the DEI on the downpipes

The thinking is this:
1.The ceramic coating and DEI wrap should significantly reduce engine bay temperatures and, as a result, reduce convective heat down the tunnel and through firewall openings, and conductive heat through the firewall itself. Airflow helps disperse heat once the pipes curve under the car.
2. The convertor and muffler will radiate intense heat towards the floor regardless of what's done in the engine bay. The larger replacement shield will block more area over the convertor/muffler, reflect more radiant heat and, unlike the regular shield, provide ceramic insulation between the shield and the floor. Since the center muffler is inches from from the convertor I'll treat it (heat-wise) as if it is a convertor. Both lie center-line under the cabin between the gear shift and parking brake handle. When combined with airflow down the tunnel its a central heating system!
3. The Heat Shield Armor is interesting because it installs without wrapping, works like a wrap (can be placed directly on the exhaust and keeps heat within the exhaust), yet calls for a small gap (pointed away from the car) to allow some heat to escape (and prevent over heating the pipe.)
 

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I do not remember ever having much of this particular problem with my GTV6's. One thing I had done was to install one of those rear window louvered covers. Some didn't like them, but since my 86 was black, the black louver set on the back window fit right in. It was one of those metal lift up ones. Did make a difference since it blocked the sun before it reached the window. Cannot do any better than that.

Keep in mind that the coolest air you can get into the car is through the hvac inlets at the base of the windshield, it being outside air. That's what was so great about door vent windows as in Alfetta's, you could turn them to blast in outside air. Miss them.

If you open the regular side windows, you can end up creating a low pressure situation in the cabin and can suck in hot air from under the car, through holes in the firewall, and from the rear. It is essential that hot air from the engine bay is not allowed to escape out the rear of the hood and into those "base of the windshield" inlets.

Another thing that can be done is to install a more modern P-Flow condenser if you have a/c, as some of us have done with the 164's. Considerably more efficient. And finally, you can get one of those solar panel driven little blowers which pulls in outside air through a partially opened side window when it is parked.
 

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Discussion Starter #7
Del,

I've had 4 different GTV6's over the past 25 years, and though the interiors are warmer then other cars,I've never been this warm! But I never had a 3L engine with a CSC type header (the front section/downpipes that connects to the headers are 3 pipes per side and don't merge until the convertor.) Then too there is little cross ventilation in the cabin with the windows open. But I'm certain I'll fix the problem!
 

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Hope so. They are fun to drive. I'm sure those headers don't help, as they will heat up much faster, being thin walled, and broadcast more heat in all directions sooner.
 

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I'm sure those headers don't help, as they will heat up much faster, being thin walled, and broadcast more heat in all directions sooner.
My vote would be to absolutely focus on those headers. Do something there first. Least costly would be to wrap them in high temp header insulation. If that doesn't help enough, and you don't care about losing a few hp, replace them with the original cast iron manifolds.

Those headers are absolutely a major culprit to your heat issue, they give off a LOT of heat into the engine bay, and under the length of the car when you're underway, and at rest - as you have noticed.

A good friend had similar heat nightmares after putting headers on his American small-block. He reported similar excessive cabin-heat problems, and it also ended up "cooking" his starter motor to failure. Then he replaced them with ceramic coated and wrapped those in high-temp insulation. Now the heat level is apparently tolerable.

Good luck!
- Art
 

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Discussion Starter #10
76,
That's what I've done! Bought 3L original manifolds from Greg Gordon and are having them ceramic coated by Swain Tech. Will match up with DEI wrapped original front section. I'm thinking that should have the engine bay cooler than stock.

I've discussed heat shielding over the cat with folks, and now realize simple thin metal original heat shields are drastically less effective than modern DEI, Heat Shield Products, Thermo Tec, etc heat shields. The aftermarket products appear to have a more effective reflective surface and, more importantly, a ceramic core or backing that acts as a thermal barrier. The originals still allow a huge amount of heat to radiate to the floor pans
 

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Discussion Starter #11
Picked-up car from the shop today (inner tie rods and boots, fuel pressure regulator, oil pressure sensor, rear fuel lines, suspension inspection). The car was outside in the sun (facing sun) for a while when I got it, which accounts for the 140F high reading for the day. About 45 minutes driving around LA with windows open in 88F weather (3:25 pm)...120F.
 
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