Under Hood Temps

It gets really warm in southern FL, especially under the hood w/ my 304 V8, but there has been zero instances of vapor lock.

My impression is the hood vents are a fix for a non existent problem.

 

Do you have vapor lock problems?

 

I did, and after adding a filter with a return, it has diminished greatly, so i figured maybe louvers could help some

 

Any thoughts on the forward v. backward question ?

 

I have mine facing to the rear, obviously,
I know the natural air flow is thru the radiator, across the engine then down and out underneath, but I have been getting some vapor lock and heat related issues with my FiTech. But I removed the F/I system before I did this mod. I have not had a vapor lock issue. I'll let you know how everything shakes out on my next west coast trip in 2024

 

I'ld run them with the opening to the rear. So the sharp edge will be away from me. I'ld also be the one cheese grating the low hanging branches and getting twigs in em.

 

Well, that should do it

 

I don't want to be a "know-it-all" but you may want to turn your louvers around 180 degrees so the air under the hood can vent out while driving. As is the air will be entering through the grill and through the louvers instead of flowing out to the airstream, JMHO. BTW, the previous owner installed the same type of louvers on the hood of my 1970 V6 CJ5. I'm not sure how helpful they are for reducing the under hood temperature but they do allow water to drench the engine and accessories every time it rains or when it's washed, YMMV.

Martin

 

I’m always open to ideas… I figure I’ll run it like this for a bit and see what happens. I’m planning to do some temperature readings as well to answer this very question. Now, as far as rain? I live in vegas, and don’t even know how to spell rain. Our average rainfall is 4”, and I don’t drive the jeep in the rain, so facing forward for me, isn’t much of an issue

 

Do what?

What if they scoop enough air to create positive pressure - and reduce the air flowing through the radiator?

 

That is an excellent question. There are approximately 14.5” of louvers, so, i don’t think it will overwhelm airflow, through the radiator, especially at my average speed of 40 mph. My thought is that airflow through the jeep will continue as always and that maybe some will be introduced via the top. At any rate, hot air should be able to escape when stopped. At least that my big brain tells me

 

Zackly what I was thinkin'.

 

I’m thinking that if that were so, then the roughly 500+ sq. In of radiator, plus however many inches of space at the bottom of the engine compartment, is woefully inadequate. At any rate, until my wind tunnel comes in from Amazon, its fun to postulate

 

I agree. But isn't that the premise you are beginning from?

Here's an idea... put some blocks under the hood hinges, on the cowl. Raise the back of the hood an inch and that will let hot air out for sure. Here up north, the old timers used to do that to create a defroster.

 

I read about the block things, and did actually try it… didn’t like how it looked. Thanks, though for the idea. As a retired electrician, here are my professional thoughts on aerodynamics There are “X” units of air flowing past the radiator, and “X” units exiting, mostly through the bottom. A few of those units are used by the engine itself for combustion. I am adding “Y” units through the top, most of which will exit the bottom with a small amount maybe for combustion. I figure those few cubic inches or so, won’t affect much, and may have a small benefit. At the end of the day, they (louvers) should at least shed some heat at slow and stop situations.

 

My devalued 2 cents: whether or not hood louvers or a scoop will function in the desired mode at road speed is going to depend a lot on the physical positioning of those. I suspect a location more towards the front of the hood will be in the low pressure area created by airflow over the grill and the leading edge of the hood. Conversely, positioning those towards the rear is likely going to subject them to higher pressure from air being lifted over the windshield. All that is moot when crawling where air passing through the radiator is going exit anywhere it can.

I made a low wide scoop for my 3B hood running its entire length and left it open on both ends. Seems to work well.

 

I like how that looks. I just took mine out for the first post louvers drive. SOTP tells me i gained 50 HP. Ok, in reality, probably nothing changed, and it hasn’t hit 100 degrees here yet, but, engine temp seemed a few degrees lower, and the vapor lock issue seems a bit better. So, who knows