Is hood insulation necessary?

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Righty Tighty

Righty Tighty

Blame it on the dog
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Just as the title says, I’m wondering if hood insulation is necessary. Is it for temperature insulation, or just sound dampening? Mine is scuffing my nice new chrome air cleaner cover, and I’d prefer it didn’t do that.

I considered cutting out a portion so that it would clear the air cleaner, or just removing it altogether. Whatcha guys think?
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I would consider it unnecessary, pretty much used to quiet engine compartment noise. Such as typical motor noise, power steering, belts and alternator charging. Take a small piece and use your Bic lighter...it will catch fire pretty quickly, now add the years of oil and gas fumes to the mix.... not on my Dart.
 
Ya.... only for those die-hard numbers match totally stock factory original concours correct example of a factory original kinda guy. In short Turf it:icon_fU:
 
Ima thinking three things;
1) that air-cleaner stud is wanting to identify where the hole in the hood should go, and
2) that will make it easy to put the hole there, lol. and
3) seriously.

Your engine hates hot inlet air.And it is impossible to correctly tune it, if the inlet air temp is constantly changing.
Consider this; at idle and parked, with the hood closed; your underhood air temp can skyrocket ; say 300 to 400 degrees. The headers alone will run !400 or hotter.
Then you put it into gear, and the rpm drops another 100/150, so the waterpump slows down..... Now your fan kick in, and it is desperate to pump that hot air all over your engine.
Then you accelerate, creating more heat, which the fan dutifully tries to push under the car, with moderate success. Finally you get it up to 30/35 in top gear.....and the waterpump slows down again, but ram-air is now controlling your rad temp, and to some degree,your underhood temp. Cruising, it might be down to 250/300 now.
Then you might kick it down into second and accelerate to 65 mph, and go for a cruise. Now ram-air is limiting your water temp to say 180, and your underhood is also down to say 200. But say you stomp on it to 100mph, screaming thru the gears.
Only about 1/3 of the energy in the fuel makes it to the crank. The other 2/3rds is split more or less equally between the exhaust and the cooling system. So your engine is creating massive amounts of heat on it's way to 100mph. Of course water-pump speed is up there, and ram-air is doing a great job of keeping the water cool. But where is the heat going? Ok sure, most of it is blasting underneath your car. But your engine is trying desperately to "suck" 500 to 700 cfm of that really really hot air, straight thru the airhorn;like a run-away nuclear-reactor, heat begetting heat.
jus saying lol.
 
Dammit, AJ! I’ve been kicking around the idea of a hood scoop since I bought the car, but I really wanted to keep it clean looking, and as unassuming as possible. Like, I want to keep it from looking like a hot rod if possible.

That said, everything I’ve done so far (and everything I’ll do in the future) will be purely functional and not cosmetic. Obviously a hood scoop would be very functional in this situation. In fact, the topic of a scoop came up in conversation when Pops was over yesterday.

I’m also extremely reluctant to go cutting up my hood. What if I screw up?? I’m confident if I take my time, I’ll do fine. Then comes the question of the finish work and paint matching. It’s something that done just enough reading up on to scare me away.

However, with temps topping 110F here in the summer, it may be a good move. I’ve noticed my water temp gets up to about 210 after 30 minutes on the interstate.
 
@Righty Tighty you don’t need a hole in the hood. Have a look at spectre performance sealed cold air, air cleaner set up or similar and duct it to the cowl. I believe it’s member @jbc426 that has a nice set up. Maybe he’ll chime in. All the fresh cool air your engine can use.
 
I had a spare hood, so it was a no brainer. Be advised that the engine is not under the center of the hood.
And also, a streeter doesn't need a scoop, it just needs fresh cold air. It don't matter where or how you get it, as long as it ain't full of dirt or water,lol.
In addition to the Specter System, I have seen;
dual snorkel air cleaners run to the core support, and
cowl induction where the air cleaner is pulling air from the plenum that feeds your heater system.
I just went with what was quick and easy. I bolted a low-profile, oval ,alloy, air cleaner base to my hood, in the center,lol; then cut out an opening and sealed the carb to the underside of the hood. Shazzam! I put a double filter on it for most of the time, but a single when I go to a show or something. Pure redneck, I know, but it runs rock solid now, and the 87E10 doesn't boil off overnight anymore,lol.
You'll figure something out. Maybe buy a good used hood; there must be hundreds of em out there......
 
Last edited:
AJ/FormS said:
Ima thinking three things;
1) that air-cleaner stud is wanting to identify where the hole in the hood should go, and
2) that will make it easy to put the hole there, lol. and
3) seriously.

Your engine hates hot inlet air.And it is impossible to correctly tune it, if the inlet air temp is constantly changing.
Consider this; at idle and parked, with the hood closed; your underhood air temp can skyrocket ; say 300 to 400 degrees. The headers alone will run !400 or hotter.
Then you put it into gear, and the rpm drops another 100/150, so the waterpump slows down..... Now your fan kick in, and it is desperate to pump that hot air all over your engine.
Then you accelerate, creating more heat, which the fan dutifully tries to push under the car, with moderate success. Finally you get it up to 30/35 in top gear.....and the waterpump slows down again, but ram-air is now controlling your rad temp, and to some degree,your underhood temp. Cruising, it might be down to 250/300 now.
Then you might kick it down into second and accelerate to 65 mph, and go for a cruise. Now ram-air is limiting your water temp to say 180, and your underhood is also down to say 200. But say you stomp on it to 100mph, screaming thru the gears.
Only about 1/3 of the energy in the fuel makes it to the crank. The other 2/3rds is split more or less equally between the exhaust and the cooling system. So your engine is creating massive amounts of heat on it's way to 100mph. Of course water-pump speed is up there, and ram-air is doing a great job of keeping the water cool. But where is the heat going? Ok sure, most of it is blasting underneath your car. But your engine is trying desperately to "suck" 500 to 700 cfm of that really really hot air, straight thru the airhorn;like a run-away nuclear-reactor, heat begetting heat.
jus saying lol.
Click to expand...
Sorry AJ
"Suck air" you know better than that. LOL
 
If you didn't have a hood pad where else would you store all that dust and dirt to sift down over your nice clean engine compartment
 
Hit the nail on the head! Every time I open the hood I’m having to blow it out with compressed air or clean the air cleaner cover. Every...single...time.
 
Our fist 67 notch didn't have it. When I would get caught in a summer time storm, traffic suddenly backed up on the interstate, hood would make steam, look like engine overheating or worse. That was a white hood too. Darker color would be even hotter.
 
The hood on the car in my avatar is an original 340 hood, though it's not original to the car, which started life with a 318. I have helped friends put these scoops on a regular flat hood before. Is there a question that I can help you with? If you need pics of an original hood with the holes, I have 2 of them in my shed that I can take pictures of without the scoops in the way. If you have a 70 or 71 flat hood it's really easy because there are places in the hood frame that locate about half of the mounting holes and the big hole through the hood.
 
I'm gonna make a guess here and others can correct me if I'm wrong, but I would bet that none of the A-bodies with 2 scoops came with hood pads on them. I've been fooling with these cars since I was 16 (1972) and I don't recall ever seeing a 340 car with a hood pad back in the day.
 
str12-340 said:
Is there a question that I can help you with?
Click to expand...

Actually, yes! I haven't done a search yet and I'm not sure if it would send this thread too far off topic, but I was just going to ask about the installation. Pictures of the holes would be fantastic.
 
isnt hood insulation kinda like bra padding?
just taking up space where the good stuff should be
 
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