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MeteorGray · 09-17-2020, 12:15 PM

I live in Louisiana, a semi-tropical state that is hard on people and equipment due to the heat. Ambient summertime temperatures in the 32C/90F to 38C/100F range are the norm.

Temperatures in the engine bay can run much hotter than ambient, of course. Batteries often fail in this heat. To help alleviate the pressure on engine bay components, I put louvers in the hood of my Mazda3. Some of them are located directly above the heat-sensitive battery. This venting of excessive heat helps.

I installed a digital temperature probe in the engine bay to keep tract of things. The gauge shows that on the highway, engine bay temperatures are exactly the same as ambient temperatures: if it's 95F ambient, it's 95F under the hood; so that's about as good as it can get. Of course, in town at slower speeds, temperatures rise a few degrees warmer than ambient; how much so depends on traffic. After engine shut-down, the engine block heat takes over for a while, causing temperatures to rise to 65C/150F or more, depending on ambient temperatures.

Even with the louvers in place, the battery and other engine bay components take a beating after engine shut-down, but having the louvers to allow it to dissipate faster helps a lot. I even installed a six-inch-diameter radiator-type fan under one of the louvers to help discharge the heat faster after parking in really hot weather. I have a timer to run the fan for 10 minutes after engine shut-down. This helps too.

Because of the heat in my area, I wouldn't consider blocking the grill. On my 2015 Mazda3, a lot of the grill is actually already blocked from the factory. Any further obstruction would aggravate the detrimental effects on heat-sensitive stuff under the hood. My car also has almost a full tray installed under the car from the factory to help the aerodynamics, but this covering actually works against heat dissipation. Fortunately, Mazda provided an opening in the tray immediately behind the engine to allow for engine bay heat to escape under the car at speed. Of course, this opening does relatively little to remove hot air after parking, since heated air rises. That's one of the reasons for my hood louvers: they provide an escape route for the rising hot air.

About fuel economy: I have noticed no effect on my miles-per-gallon with the louvers. So, they have proven to be all-win and no-lose for me.

09-17-2020, 12:15 PM	#9 (permalink)
MeteorGray Master EcoModder Join Date: Jul 2015 Location: Louisiana Posts: 361 Thanks: 275 Thanked 132 Times in 102 Posts	I live in Louisiana, a semi-tropical state that is hard on people and equipment due to the heat. Ambient summertime temperatures in the 32C/90F to 38C/100F range are the norm. Temperatures in the engine bay can run much hotter than ambient, of course. Batteries often fail in this heat. To help alleviate the pressure on engine bay components, I put louvers in the hood of my Mazda3. Some of them are located directly above the heat-sensitive battery. This venting of excessive heat helps. I installed a digital temperature probe in the engine bay to keep tract of things. The gauge shows that on the highway, engine bay temperatures are exactly the same as ambient temperatures: if it's 95F ambient, it's 95F under the hood; so that's about as good as it can get. Of course, in town at slower speeds, temperatures rise a few degrees warmer than ambient; how much so depends on traffic. After engine shut-down, the engine block heat takes over for a while, causing temperatures to rise to 65C/150F or more, depending on ambient temperatures. Even with the louvers in place, the battery and other engine bay components take a beating after engine shut-down, but having the louvers to allow it to dissipate faster helps a lot. I even installed a six-inch-diameter radiator-type fan under one of the louvers to help discharge the heat faster after parking in really hot weather. I have a timer to run the fan for 10 minutes after engine shut-down. This helps too. Because of the heat in my area, I wouldn't consider blocking the grill. On my 2015 Mazda3, a lot of the grill is actually already blocked from the factory. Any further obstruction would aggravate the detrimental effects on heat-sensitive stuff under the hood. My car also has almost a full tray installed under the car from the factory to help the aerodynamics, but this covering actually works against heat dissipation. Fortunately, Mazda provided an opening in the tray immediately behind the engine to allow for engine bay heat to escape under the car at speed. Of course, this opening does relatively little to remove hot air after parking, since heated air rises. That's one of the reasons for my hood louvers: they provide an escape route for the rising hot air. About fuel economy: I have noticed no effect on my miles-per-gallon with the louvers. So, they have proven to be all-win and no-lose for me. __________________ Last edited by MeteorGray; 09-17-2020 at 05:24 PM..