Louver Install w/ Pictures and Actual Cooling Data

[AverageTanner]

This weekend I installed the louvers I bought here:

Small Angular Universal Hood Louvers

Improve cooling and downforce with TrackSpec's Small Angular Universal Hood Louvers. Designed for performance and durability, it includes a full install kit.

trackspecmotorsports.com

After much research of the forum I found most of the people that have installed louvers say “they work great” but have no data to back it up. For the two weeks prior to installing the louvers, I made a spreadsheet that included ambient temperature, humidity, length of drive, high coolant temperature and average coolant temperature.

For those wondering how I’m monitoring this info - I have a temperature sending unit cut into my upper radiator hose and a GlowShift gauge mounted on my A-pillar.

Below are pictures of the finished louvers.

My first drive after the installation DOES seem to yield a lower coolant temperature, but I will verify after a couple of weeks when I have more consistent/sufficient data.

 

[Bambusiero]

I like those louvers. Neat look, and easy install, looks like.

From what I've read, the main hoped for benefit would be lower underhood temperature at slow offroad speed, where there isn't nearly as much velocity induced under-vehicle negative pressure to encourage back-down-out airflow. Secondarily then, hopefully, the fan will move more air for a given RPM by having more open exit area, and coolant temperature would reduce some.

Recommend recording OBD2 IAT readings as well. That may be the most direct change to see. But, I've seen that have some time delay lag between cause and effect, so that makes it harder to see the correlation. Averaging required.

However, there's been a number of attempts at this kind of thing, including lifting the rear edge of the hood. But very little benefit was achieved, so it has not become widely adopted.

Make sure your so called "engine under shield" is in place, and all the wheel well rubber skirts too. Those are said to guard against recirculating hot air through the radiator at low speed. The louvers should contribute to that too, so you need all the parts working together, or the results might be inconclusive.

Good luck with yours. Hope you see some benefit & fill us in.

 

[OffRoadScott]

I am interested in how this works out for you. I would be interested in one of these for my Land Cruiser anything to do to keep under hood temps down here in the AZ heat.

 

[junior80]

same here. I had noticed that after hosing off the bonnet of the cruiser and driving off, water droplets would still sit on the centre of the bonnet out of the wind in a bit of a low pressure area I guess due to the air flow off the front of the car. I decided in my head that the low pressure area would really make bonnet louvers inefficient as there wasn't a nice high pressure flow of air across them to draw the hot air out from underneath, so the placement of the louvers would be muy importanté.

Slow driving in low range is going to be completely different, thats where your fan shroud and rubber flappy panels in the wheel wells come into it. I was looking at it from the perspective of driving a lot of hours on the beach or driving/ towing a long distance where theres a long period of time for the heat to really soak into everything. I noticed after about 5-6 hours of driving that the floor and trans tunnel really get a good amount of heat into them, and you need a while for the whole lot to cool down again.

I could lay down a layer of thermal stuff on the floor but thats more masking the symptoms and not treating the cause of the issue.

 

[junior80]

but I think they look great @AverageTanner

 

[Bambusiero]

...muy importanté...

A bit of "south of the border" local lingo?

...driving/ towing a long distance where theres a long period of time for the heat to really soak into everything. I noticed after about 5-6 hours of driving that the floor and trans tunnel really get a good amount of heat into them, and you need a while for the whole lot to cool down again...

But the whole engine bay is awash in constantly refreshed engine coolant temperature air (just a few degrees less, probably), so having a relatively small additional engine bay opening isn't going to change that radiator outlet airflow temperature much at all. There is really a very large engine bay airflow outlet, down and back, so you can't say there's an airflow restriction at all. And the fan makes this a forced air system by a large margin, rather than convection due to heating / expansion / buoyancy. If you let a small percentage of that radiator temperature air out the top, then the airflow down and back is moving a bit slower, but still has the same temperature, so it still heats the firewall / floorboard just as much?

 

[1973Guppie]

did you have to cut any hood ribs? I like the placement, I have a set of 3 but have not installed yet due to trying to figure out how to place them without cutting the ribs

 

[IoN6]

Looks great! Underhood shot of them installed?

 

[junior80]

A bit of "south of the border" local lingo?



But the whole engine bay is awash in constantly refreshed engine coolant temperature air (just a few degrees less, probably), so having a relatively small additional engine bay opening isn't going to change that radiator outlet airflow temperature much at all. There is really a very large engine bay airflow outlet, down and back, so you can't say there's an airflow restriction at all. And the fan makes this a forced air system by a large margin, rather than convection due to heating / expansion / buoyancy. If you let a small percentage of that radiator temperature air out the top, then the airflow down and back is moving a bit slower, but still has the same temperature, so it still heats the firewall / floorboard just as much?

that makes total sense (after re-re-reading it) So considering all that, improving the amount of air moved through the radiator by the rad fan would be the best option? and it'd be even better if it were able to flow better down and back out of the engine bay? Maybe I just need a better heat shield between the firewall and exhaust.

I have a lotus super7 replica thing called a PRB, (that I never drive and should) it has a naca duct just under the tail end of the gearbox that draws air up from under the car and directs it backwards down the trans tunnel and out around the rear diff, the motor's sump pokes out the bottom otherwise its a flat floor under there. That duct combined with the 'numberplate holder front wing' suck that car onto the road pretty good. driving the car without the wing at the front lets so much air under the car it blows the cover off the trans tunnel that sits around the gear stick, so It moves a lot of air. now, although thats a ~550kg lightweight vs the huge and heavy landcruiser, I'd like to think there'd be some things I could take from it but really it's probably all too hard and not worth the difference, also, I forgot why i started typing

 

[Enders]

I’ve been very happy with my set. Still need to reinforce where I chopped a rib tho. It’s been low priority. While current under hood temps have not been an issue, I’m planning on adding Wits Ends heat generator upon release.

 

[Bambusiero]

...improving the amount of air moved through the radiator by the rad fan would be the best option?

That would be more about improving radiator/cooling system efficiency, rather than underhood temperature.
I'm proposing that, overall, under nominal operating conditions like normal driving speeds, normal loads, cooling system working as it should, that the underhood temperature is pretty much the same as engine coolant temperature (a little less), which is regulated by the thermostat. It's pretty much a fixed quantity, and should be so. I don't think there is normally a radiator/cooling system efficiency problem that needs solving. It works fine. Except at low speeds, crawling, heavy traffic, A/C running. That's a different situation that may need help, and maybe where louvers come in to contribute? And auxiliary electric pusher fans.

...and it'd be even better if it were able to flow better down and back out of the engine bay?

Don't think there's an improvement to be had. It's a great big gaping hole on both sides.

...Maybe I just need a better heat shield between the firewall and exhaust.

Now...that's altogether something else. Everything I said above completely ignored this.
The exhaust manifold and pipes are much hotter than the radiator outlet airflow temperature.
So, there's local air heating going on, over and above the engine coolant temperature.
Also, direct IR radiative heating. Anything nearby in line of sight.
Ever take a look at how Mr.T designed the manifold heat shield?
It has louvers to scoop in airflow coming from the front.
Hmm. A very small portion of the existing airflow, directed in a specific way over an extra hot item.
Various improvements possible here. Some simple, some elaborate and hard to fabricate.
Mr.T did what was simplest and stopped there.
I think louvers could help exit some of this super heated air when airflow is low...maybe.

...I have a lotus super7 replica thing called a PRB...

Must be an absolute kick in the pants to drive! S***t eatin' grin, bugs in the teeth! Yeehah!

 

[AverageTanner]

Alright so it's been a few weeks since I installed the louvers... No I did not have to cut into any of the hood supports, although I was very close to drilling a hole for a rivet through on of the supports (no big deal).

My under hood insulation was falling apart in the areas where I put the louvers so I just cut them straight back along the under hood support structure. As you can see, I eyeballed it with a razor knife and it's a little bit off.

Now for the data. I wanted to run this testing to see if the louvers being in place were directly related to water temperature. In hind sight, I really should have gathered data on both my under hood temperatures and IAT's pre and post louvers, but I didn't. Oh well.

Highways speeds there is little to no effect (0°-2° cooler water temp). The biggest area that I noticed a change is pulling in to and driving down my driveway (for reference: I live down a quarter mile dirt road - do to dust and being neighborly, I usually don't travel down it much faster than 15 mph). The louvers don't seem have a direct correlation with the water temperature at slow speeds, but they did seem slow down the inevitable. What I mean by that is the rate at which my water temperature rose. My Cruiser at it's hottest, typically runs around 196°. Before installing the louvers, I would hit that 196° by the time I put it in park. After installing the louvers, I would come down the driveway, park, and in order to hit 196° again I had to wait 5 minutes in my driveway. This was on a day that was 92° outside with 35% humidity, compared to the first trip (without the louvers) at 91° and 38% humidity, so the ambient temperature/feel was almost identical. The drive itself was from work to home on both occasions (a 10 mile, 20 minute trip consisting of getting going to 60mph, slow down for stop lights, back up to 60, slow down again, back up to 60, stop at light, etc).

Another thing that I have noticed is that the fenders do not get as hot to the touch after trips. And after a trip, if you place your hand above one of the louvers, it's shockingly hot!

Based on what I've found, there are some obvious benefits to the louvers. Are they easy to install, yes. Do they look cool, yes. Will they cure your overheating problem, no. Would I do it again, probably.

 

[1973Guppie]

what I like about these louvers (as compared to others I have seen) is that they look very open flow vs. the stamped type of louvers. Seems like they would flow much better.

 

[Moog]

Have you tried covering up or taping the louvers to see how much it makes a difference?

 

[AverageTanner]

Have you tried covering up or taping the louvers to see how much it makes a difference?

I monitored and tracked my temperatures for two weeks prior to installing the louvers.

 

[Bambusiero]

Nice job @AverageTanner. I like your comparable data.

Very interesting about the fenders not getting as hot.
Maybe the upward escape route for hot air means that the whole engine bay is not quite as "filled up" out to the edges with hot air, and ambient leakage flow at the edges isn't being quite as overwhelmed by the larger, hotter, radiator flow.
So, stuff out at the edges, battery compartment, etc., may stay somewhat cooler. Keeping the battery compartment even a few degrees cooler would help battery life, at least in the hot low desert like Arizona.
This may lower IATs for those without snorkels, specially at slower driving speeds. I've seen a strong speed influence on IATs. Anything below highway speed and IAT goes way up, I think because large volume of hot radiator air is dumping out the lower back edge of the USPS fender where air intake is coming from (I think?). It takes highway speed to really dilute that with fresh outside airflow.

 

[Bambusiero]

How about cabin fresh air intakes? Do you get heated air at the vents?

 

[inkpot]

that makes total sense (after re-re-reading it) So considering all that, improving the amount of air moved through the radiator by the rad fan would be the best option? and it'd be even better if it were able to flow better down and back out of the engine bay? Maybe I just need a better heat shield between the firewall and exhaust.

I have a lotus super7 replica thing called a PRB, (that I never drive and should) it has a naca duct just under the tail end of the gearbox that draws air up from under the car and directs it backwards down the trans tunnel and out around the rear diff, the motor's sump pokes out the bottom otherwise its a flat floor under there. That duct combined with the 'numberplate holder front wing' suck that car onto the road pretty good. driving the car without the wing at the front lets so much air under the car it blows the cover off the trans tunnel that sits around the gear stick, so It moves a lot of air. now, although thats a ~550kg lightweight vs the huge and heavy landcruiser, I'd like to think there'd be some things I could take from it but really it's probably all too hard and not worth the difference, also, I forgot why i started typing

I doubled up on the OEM heat shields to cut down on cabin heat. The studs holding the firewall (top) shield are long enough to hold a second one. By leaving the original nut in place, it created a thin dead zone between the two shields and still had enough sticking thru the second one to put on another nut. Easy peasy. The big cat shield is really thick, so can't use the first trick to mount it. I bought rod coupling nuts and used them to replace the original nuts on the original shield. Then I found really short bolts to run thru the second shield and into the open end of the rod coupling nut. It DID take some SLIGHT reshaping of both the firewall shield and the cat shield to fit in the available space. I bought what I have been told is the LAST OEM #3 exhaust heat shield in the world. A good used one will work fine. Or, a piece of 4' chimney pipe is pretty easy to shape into place for the 3rd position. My exhaust has been rerouted over the frame like a 93-94, so there is room for a shield over that section where it comes out along the transfer case. Much cooler floor according to my wife. It used to get soo hot when I was running WOT up the mountain passes that she had to pick her feet up off the floor. Not any more.

 

[inkpot]

Alright so it's been a few weeks since I installed the louvers... No I did not have to cut into any of the hood supports, although I was very close to drilling a hole for a rivet through on of the supports (no big deal).

View attachment 2037524

My under hood insulation was falling apart in the areas where I put the louvers so I just cut them straight back along the under hood support structure. As you can see, I eyeballed it with a razor knife and it's a little bit off.

Now for the data. I wanted to run this testing to see if the louvers being in place were directly related to water temperature. In hind sight, I really should have gathered data on both my under hood temperatures and IAT's pre and post louvers, but I didn't. Oh well.

Highways speeds there is little to no effect (0°-2° cooler water temp). The biggest area that I noticed a change is pulling in to and driving down my driveway (for reference: I live down a quarter mile dirt road - do to dust and being neighborly, I usually don't travel down it much faster than 15 mph). The louvers don't seem have a direct correlation with the water temperature at slow speeds, but they did seem slow down the inevitable. What I mean by that is the rate at which my water temperature rose. My Cruiser at it's hottest, typically runs around 196°. Before installing the louvers, I would hit that 196° by the time I put it in park. After installing the louvers, I would come down the driveway, park, and in order to hit 196° again I had to wait 5 minutes in my driveway. This was on a day that was 92° outside with 35% humidity, compared to the first trip (without the louvers) at 91° and 38% humidity, so the ambient temperature/feel was almost identical. The drive itself was from work to home on both occasions (a 10 mile, 20 minute trip consisting of getting going to 60mph, slow down for stop lights, back up to 60, slow down again, back up to 60, stop at light, etc).

Another thing that I have noticed is that the fenders do not get as hot to the touch after trips. And after a trip, if you place your hand above one of the louvers, it's shockingly hot!

Based on what I've found, there are some obvious benefits to the louvers. Are they easy to install, yes. Do they look cool, yes. Will they cure your overheating problem, no. Would I do it again, probably.

So, what was the temperature when you got to the end of the driveway and put it in park WITH the louvers?

 

[Bambusiero]

I doubled up on the OEM heat shields to cut down on cabin heat....

Oh, cool! (I know, dumb pun intended )
Really good to know how you did that and how it worked out.
I've been toying with that kind of idea for a while, and will make use of your clues.