The biggest thing I've notice to reduce my under hood temps is after I have my headers JetHot coated.
My opinion is if you want to reduce under hood temps this is really the best way. Keeps radiator hot air from entering the compartment.



With some good fab work and relocating any radiator fan to the front I think C3's have enough room to do this.

 

If it rains while out driving it is what it is. It's happened a lot lately too. Stays pretty clean as long as you're moving. I've seen they make shine type of catch trays and/or baffles for a certain car. I couldn't find anything to try to relocate and still keep reasonable function.

Say if I drive to work and it starts raining while parked there I'll throw this on it. I made out of abs and plastic welded the tabs on there. Tabs are to keep it in place.



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I bet there would be a way to make baffles/tray to capture any water similar to shaker style hoods. The trick would be making the trays and baffles in a way that doesn't restrict the airflow through them, while capturing the water at the same time.

 

With the "Layed back" radiator in a C3. perhaps there might be room. airflow would be taking some real turns and opening and closing the hood could be very interesting. I'm thinking I'd give this idea a pass.

 

I have a bit of a debate going on an overheating thread where Resdoggie insists the air exiting the radiator is in fact not "hot" air and cools the engine as well as supplies his air cleaner in another thread where I made the mistake of referring to it as such. I argued that I believe it to be 20-30 degrees over the incoming air temps.

 

The only way to prove or dis prove his statement would be for you to attach heat sensors in front of and behind your radiator, monitor the temperature differences and record your findings.
All I know is you can roast a chicken behind the radiators on an M1 idling the the Sahara, but what matters is that the engine runs at its proper temperature.

 

UMm, whoever you are arguing with needs to take a physics class. How is the air supposed to cool the water without heat transfer from the water to the air. Once the heat transfer is complete does the air immediately cool back down to ambient temp before traveling through the engine compartment?

I think I will take my thermocouple and do some experiments.

 

what is your idea of hot and what is his idea of hot. Its hotter than the air going into the front of the radiator, but it wont burn you like the radiator fluid will. THe heat of the coolant is transfered to the air as it passes through the radiator heating the air and cooling the fluid. because that is how cooling works. But its not the same temperature. So its just a question of what he thinks hot air is and what you think hot air is.

 

that was discussed.. I mentioned its relative but I consider the air on a summers day to be pretty warm already and the air coming out of the rad to be 20 to 30 degrees hotter. So typically around or just over 100 degrees.. Enough to where it would hurt performance if I were to use it rather than a CAI with cooler air.

 

Oh ya...CAI have been beaten to death and proven to provide big performance gains. All new cars and trucks have been using them for years. You definitely dont want to suck under hood air into your motor if you are into performance. Same with the fuel lines. I run mine up to a fuel cooler in front of the radiator before it goes back to the carb. Cold air/ fuel charges boost performance greatly. They have done a bunch of shows on Engine Masters proving that. In fact they always talk about trying to keep the engine cooler to boost the HP numbers and trying to maintain stable oil temps as well

 

I drove around for 2 days with no hood... after putting the hood back on I actually noticed once the car warmed up the power seemed to drop off just enough where I thought something was wrong... took me a few minutes to figure it out. once I popped the hood and felt the very hot air cleaner I figured thats it. I'm actually shopping for an L88 fresh air box now to mount to my twin turbo high rise hood.

 

Thank you, OldCarBum for starting this thread.

I’ve been planning one of these hood vents for my upcoming build as well. Will these vents provide additional cooling for the engine compartment? Or is it just a cool fad that a lot of C3 guys have adopted for their cars?

We all understood that heat rises. Unfortunately, our standard Corvette engine compartments are really closed off. With the basic hood like my 76’, there is little space for the heat of the engine bay to escape, either while driving or while stationary. The foot wells of my car get extremely hot while summer driving.

The addition of the L88 hood provides a little head room for the high temperature air to rise and escape. And with the addition of the air vent another escape route is realized.

The Bernoulli affect will help draw more hot air from the engine bay while in motion. And as bluegtp photo demonstrate, hot air will rise through the vent while stationary. Keep in mind that for every cubic foot of air that escapes through that vent, a cooler cubic foot of air has to be drawn from elsewhere to replace the warm one lost. And that air won’t be coming through the restricted radiator. The quicker you exchange one cubic foot of hot air with one cubic foot of cooler air, the less time there is for the hot air to soak the engine bay.

I believe the vents are a positive addition for a high performance engine compartment. For a standard Corvette with a 200-300hp engine, perhaps this is not the way to go. A well maintained cooling system is good enough for a standard Corvette.

I’m not a fan of hanging oddball stuff on Corvettes. I really like the classic lines of the C3 Body. I believe these vents are tastefully designed and they look good atop the L88 hood. So, like OldCarBum, I’m going with them, too. (and I’m going with the 496)

 

Thanks 76-Vetteman,
I totally agree with your statements and that is why these hood vents will work perfect to allow hot air to escape when stopped and will pull in ambient outside air at slow or high speed.
Any escaping air will be replaced with cooler air drawn up from underneath when stopped.
These vents are aluminum, high quality pieces that can be painted to match any color, which I plan to do to help it disappear into the hood.
Thanks again!

 

Every c-3 aerodynamics is differrent depending on the angle of body rake, but you generally only have "Ram air" up front and near the base of the wind shield. Every place else is low pressure and draws air out of the engine compartment from the rear of the radiator.

 

It’s all about air circulation.
It doesn’t matter where it comes from as long as it’s moving and the hot air is able to escape.
Think of it as the attic in your house.
The air is trapped, hot and unable to escape.
Now add a roof vent and you can stand under the vent and feel the hot air rise up and exit out the vent.
Allowing the hot air to circulate up and out of the attic allows the attic and your house to cool.
Add a little wind outside and the wind will drawl the hot air out of the attic at a quicker rate adding to the cooling effect.
I’m also removing anything that will improve air flow through the side fender vents, like the vapor canister, windshield washer tank and going to a Vintage Air a/c system to remove the a/c unit on the passenger side.
Less restrictions for more air circulation.
More air circulating through and out of the engine compartment will allow more air to be pushed through the radiator or pulled through it when the fans are operating.
Right or wrong, that’s my theory and it doesn’t have to be rocket science.

 

Someone could space up the hood latches to raise the rear of the hood to help get rid of hot air.

 

The rear of the hood is very close to the high pressure area at the base of the windshield p. You could try it with pieces of yarn taped along with bottom back edge and see if air is coming out while driving 70 mph or is that air going back in to the engine.

 

It would help hot air escape stopped or at slow speed, but as stated by Gkull at speed the low pressure area behind the hood would pull air in.
And who wants to drive around with the hood popped up?
Flaps in the radiator shroud will also help with air flow at speed, but I’m mostly concerned about stopped and slow speed temps building up.

 

My big hood vents are like a chimney with heat waves coming out!

 

!