That sounds encouraging! Glad something I said actually worked for once

You can definitely make the barrier more effective by using some purpose built heat shielding (like that dual layer aluminium we were discussing earlier) or lining your existing barrier with something non-conductive to heat. But I figured stopping the radiation would be half the battle, which a sheet of damned near anything would do (it's harder to find materials that WILL transmit heat radiation than materials that won't).

If you wanted to be cheap, you could line it on the cold side with one of those windscreen sun heat shields you can buy for a few bucks at almost any auto parts store, walmart, etc or one of the various heat insulation products you can get from hardware stores. Just line the cold side to reduce heat conduction and leave the hot side radiation-barrier as sheet metal which is more suited to soaking up the high temperature and sending it elsewhere.

 

Hey F22, did you notice much difference in the heat in the cabin after you had parked up for a while and then drove again or have you not tried this? I was thinking your vents should reduce the heat soak a lot when the car is stopped.

 

The car cools down quite quickly now. Within 30 minutes, it is normal or ambient temp inside. The hood vents definitely help out that way!

 

We have pics of the heat shield mod. I took a long careful look and figured out two attachment points to hold up the heat shield. The first one is a hole in the frame, just forward of the engine. The second one, is the leftover thread on the bolt that holds the lower steering gear box, right below the #3 and #5 Exhaust on the driver's side.

Here's that nice little hole, but look at how big it is! I don't want to put a giant bolt in there, this shield isn't structural, nor did I want to jack up the car and have to hold it from the bottom either.



So here is what I came up with. Works great! Just fold it and push it down the hole and wah-lah! It tightens really well.



OK, look straight down and you can see where I bolted the strap to the excess thread on the lower steering gear box. It is a little floppy, though and either needs to be one piece with the shield or a thicker aluminum, but this is a quick-and-dirty prototype, so excuse the workmanship.



Now a view from the front. Note the protection the gear box now has.



Here is a view of the entire shield from the top, looking from the back, towards the front. Note that it goes across the whole exhaust system and even wraps around the #7 header at the bottom of the pic. Man, was that a lot of bending and adjusting! I spent the whole weekend on this!



Here is an underside view of the back of the engine block, showing the heat shield and how it wraps around the #7 exhaust. I had to drill another hole and wire that, to the reverse-lock-out cable bracket, because it was kind of floppy, but after that it was solid. Need to figure out how to either strengthen the two up front or attach it to the firewall, with rubber insulation, but sometimes, you have to do, what you have to do.




Finally, here's an in-car view, out the windshield and looking out, as we travel north on a desolate highway.

 

F22, I' sorry, but I don't know the type of manifold on my Vette as they were on the car when I purchased it. In reference to the problem of the steering box being hot, I can see how this could be a problem as I looked and my steering box is only about 1.5 inches from the manifold.

 

Regarding the type of manifold. If it's stock, it's going to be a single cast piece, that's box like, versus the headers, with individual tubes running out of each exhaust.

I think you have the stock manifolds, but take a look and also, next long drive,on the inside of your car, behind the brake pedal, check the base of the steering column and tell me how hot it is, relative to the other areas, because, that's what's dumping heat into the cabin of my car; the steering column!

 

F22, I know the manifold is stock, but I don't know if it has to be a certain type to fit the D shaped openings on the ZZ4 heads. I will check the steering column for a heat reading the next time I go for a drive, and report back on it.

 

F22, just wanted to let you know that I posted a question on the C2 Forum page and have been getting some comments from the C2 community that they suffer the same problems with heat. The title of the thread is, "Interior Heat???" So it is not just C3s. I am still very puzzled why some cars have an issue and others don't. I'm sure you saw that AirbornSilva and I started threads this morning asking for info from the forum members, so hopefully we will get some valuable info from one or both of those threads.

I did not end up bringing my car to work today because of meeting schedules, but hope to bring it in tomorrow.

John

 

That troubles me too. Some C3's, no problem at all and others, you are in a serious hurt with the huge amount of excess heat. I'm with you on this one, because 45 minutes an hour and man, I am frying and dying at the same time.

The poll is just as lopsided. Some C3's hotter than heck. Others, not so much and this with a mix of headers and factory stock manifolds. Makes me wonder, if there's another factor we're missing?

 

There is a variable that I have not seen mentioned here that I feel will make a big difference on my car. That is what RPMs does the car run at when driving. I have a 1971 Chevy C10 that had at one time a 3.90 gear 28 in tall tires and a TH 350 with a 2500 RPM stall converter. Even with A/C it was super hot in the truck. The floor, fire wall, and kick panels were very hot. If you drove on the highway for a while the kick panels were so hot you could barely touch them. Now same engine but smaller cam, same headers and exhaust but 3.73 gears, 29 in tall tire and a 700R4 with stock converter. The heat problem is goon. No real change in water temp, always runs around 165-180 but if you stop and open the hood the difference in the under hood temps between the two set up is quite amazing. Before the oil dip stick would be too hot to touch and would smoke. Now it’s never too hot to touch. I have had a similar experience in two other vehicles, one a Suburban different gears and also with a 83 Z28 with and with and with out the over drive. A friend has a 80 Vette with 2.73 gears and he does not have heat problems like my 79.
If you can cut down on the source of heat from the start it would be easier to deal with the heat that’s there. If your driving down the road at 3500 RMPs verses 2000 RPMs there is going to be a lot more heat. I know this is not a fix to the heat problem but it is something else to look at.
My 1979 Vette has a T-10 with 3.55 gear. I plan to change out to a 5 speed with over drive and I know this will contribute to dropping the in cabin temps.
F22, I like all the work you are doing on this. I really like the hood vents!

 

Mac, I think that you have something there. I will hopefully be getting my 5 speed delivered soon and hope to have it in by the end of next month. I am going to be doing other things to help bring down the cabin temps when I put the 5 speed in so I'm hoping that the combined effects off all will make it a pleasure to drive in the summer.

 

Mac, thanks for the valuable input. That may very well be a big contributor to what's going on. I too noticed how hot the engine was as well. Glad you like the hood vents. I may be starting to sell them soon, to those who are interested.

 

Update: We're going to set up the Ram Air this week. I came up with a very simple design for a scoop. Thought I'd have to fab a scoop, but I came up with this instead!

A Shop Vac 8" Utility Nozzle, that feeds a 2.5" hose!!! Put this behind the grill and run that hose into the engine compartment, through the forward fender liner and you've got cool air at velocity, pumping into the engine compartment.

 

I'm sure RPM could be a contributor, though my car is a 5 speed Tremec box with a 3.73 diff. Sits below 2k on the highway and I usually don't rev it much past 2500rpm just cruising around the city. So that's definitely not the only contributor.

 

So I took the Vette for a ride after work today, not a long ride only about 1/2 hour with ambient temps in high 70's, here's what I found. when I pulled into the garage I left it running and measured temps with IR gun, first I measured inside at the steering column support on firewall, it was 125*, the cheap rubber floor mat was 105*, under gas pedal was 99*. I opened the hood and measured that side of steering column support, it was 180*, I then measured the steering column above rag joint and between firewall, it too was 80*. I then measured the rag joint temp it too was 180* so it does soak up and carry the heat. I measured the steering box close to where the #5 header is and measured 289*. All that was only after a short drive and mild temps.

 

Wow that's a hot rod for sure!!!

 

You know, FatCat's comment about 'Hot Rods', coupled with Mac79's experience, led me to recall thinking, just that last weekend. I popped the hood after one test sesh and the whoosh of heat, that billowed out, made an impression. Thinking here, that maybe modified, high performance motors, coupled with high rpm drivetrains, might have a way bigger caloric output, than the engine bay can handle.

I wonder how many of the 'Broiled Soles' club have hi-po engines. I do. I wonder too, how many of you are running alumimum heads. Besides being lighter, isn't one of the benefits, increased horsepower, because they run cooler? Here's my take; for that head to run cooler, does it not have to get rid of the heat at a faster rate, than, let's say iron?

Mac and Fatcat sure got me thinking. Is your rolling toaster a hard running car?

 

Holy hell, 289 degrees? Yeesh, lol. I imagine mine will be similar the way my headers wrap around the steering box, creating a nice oven effect.

Although I still don't think the rag joint will be transmitting the heat. It might get hot, yeah, but that doesn't mean it's transmitting the heat. It's like on a cold morning, a metal handle will feel a lot colder than a plastic handle of the same temperature, or a warm metal handle will feel a lot hotter than plastic handle of the same temperature. The metal is willing to transmit the heat a lot more readily where as the plastic will be hot, but will hold the heat in itself rather than transmitting it.

I'm sure the rag joint transmits some heat, but unless there's some metal -> connection I don't know about, I think it'll be negligible and I'd suggest the heat of the lower column comes from radiation from the exhaust more than heat conducting through the rag joint.

 

I got roughly the same temp above and below the rag joint too, except with the shield it was only 156 or so, versus 190 the other day and I too, if I'm reading correctly, wondered about the rag joint.

 

It is a mild 350 that on a dyno was 335 hp at the wheels, but that was with iron heads. I am in the process of a frame off rebuild and I now have aluminum heads but it will be 6+ months before I think she will be running. Last July 2012 I drove it from TX to UT and the floor next to the accelerator pedal got so hot that it burned my leg and looked like a bad sunburn for a week. I am working on figuring out ways to keep the car cool so this has been a thread that I have been following closely. Here is a link to my car and you can see the insulation that I installed under the car and I have some info on a test I performed to test it with a heat gun. http://forums.corvetteforum.com/c3-g...ld-thread.html

F22, Keep up the good work that you are doing!