Under Hood Temps

Would it seem reasonable to open up the firewall into the cowl vent and seal the two, to create a means of releasing under hood air ? I dont have any hvac, so, not going to lose anything there

 

Hmm....interesting thought. One potential issue might be the draining of water back into the engine bay instead of going out the hose and down and out, unless you leave the vent hose hooked up? I can imagine you get some really hot underhood temps there in the desert. Another thought is to buy another hood and vent it somehow, with either louvers or openings of some sort for those hot days in the summer and then swap it back when it's a little cooler.

 

The under hood temperatures on my southern FL '79 304 V8 gets very hot after operation. Hot enough to not want to touch the hood prop rod longer than required to secure the hood open.

The dash gauge shows the coolant temperature to be fine during operation.

When my CJ-5 is operated near the end of the day, then I will prop open the hood when done, to drop the temperature faster, to permit covering for the night w/o having to worry about trapped heat.

There is no interest / perceived benefit from modifying the engine cooling on my vehicle. Mine has all good thermals.

 

The cowl vent? Is that in front of the windshield base? (...no such thing on my Earlies.)

If so, I think you'd find that is aerodynamically a high-pressure zone, meant as an intake, and may not "release" air.

How about louvres to the inner fenders?

 

Yep, leaving the hose in is part of it, and with the amount of rain we get, not sure it would be an issue. All i know is that its hot !!!!!

 

I thought about that too. I’m thinking at high speed it MAY be an issue, but at the very least, would vent air at low/stop speed. Besides, 50 is about the fastest i go anyway

 

That definitely won't work with the windshield down.

 

heat shielding or ceramic coating on the exhaust would probably do good. I'm in the process of fitting and making shields for the exhaust on my F143, so far it's helping the floorboards haven't measured any under hood temps yet

 

I was gonna do something like this for my XJ..

 

Tymbom did this

if there were any hot rod places near me I would probably put louvers in the same place

 

I like the idea of louvers/screens, but, I’m trying to preserve the exterior look as best i can

 

Interesting idea. Maybe add a small 12v fan to draw air through the hole you create in the firewall? That would work at slow speeds only (stopped in traffic, wheeling, etc.), of course.

I also have no factory HVAC (Summit race car heater) - or a drain hose on the cowl box. My wife loves the water hitting her feet when we get caught in the rain. I need to add the drain and am going to consider your idea.

 

You know what? Ive thought twice about this. I’m not driving a museum, and louvers would far from detract from the overall looks. Further, who cares ???

 

With the false vents on jl fenders the average person wouldn't know the difference.

 

This on a cj5, but you’re right. I’m being silly thinking that everyone is a purist, and that this is a museum build

 

Just ordered some hood louvers

 

Yes I put in hood louvers

 

So, as I’m waiting for the louvers to be delivered, I’ve been thinking…forward or backward? Forward pros…maybe cool air kinda forced into engine compartment, instead of preheated by radiator/engine. Cons i guess would be any water pushed in. Reverse pros…maybe relieve any high pressure area under hood, and allow more air to flow. At any rate, sitting in a parking lot, heat can escape regardless of direction. Too much thinking ?

 

Too much guessing. Any actual evidence this is necessary - or effective? For instance, is there any measurable benefit if you try driving with the hood propped open an inch or two?

My guess is that any significant extra cooling, if actually needed, would be better done working with the liquid cooling system the engine already has.

 

It’s more for letting out any ambient heat in a timely manner to help mitigate vapor lock, but, its all in fun as well