Heat soak - vented hood options that are not "louvered"

Chuck33079

Maybe some kind of extractor setup on the under panel? Bring the air out the bottom?

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

dmhenderson

Zspeed nismo undershroud would probably do that - it's vented but I'd be sacrificing downforce.

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Chuck33079

It makes no noticeable difference in temps. The vent is under the oil pan. You could cut a vent further up.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

Chuck33079

The scoop is pretty much a non-starter. The potential for messing up airflow is too high without a ton of research. OEMs that use scoops have wind tunnels to use. Since we don't, were stuck with vents. Even if the vent isn't 100% dead on in the right place, it will still make a positive difference as long as its placed as far forward as you can get it.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

synolimit

That and when stopped the heat pours out like a volcano!!! Its insane how fast and how much comes out. So in traffic you'll be much cooler.

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13 370z-

Chuck33079

My guess would be a vent in front of the motor and upgraded radiator and fans are going to be about all you can do.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

dmhenderson

I think I'd go look for bigger radiator fans before I try to upgrade the radiator itself. Space comes at a premium under there these days.

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Chuck33079

I did the radiator, and before next summer ill swap out the fans. At least in TX it seems like you need to do both. If that's not enough its time to start cutting into the hood.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

synolimit

Why get fans? Just turn them on at a lower temp right?

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13 370z-

Alstann

Oh of course. I'm just saying in my post that I think the ideal way to improve heat transfer in our cars, and most cars in general is to vent the hood. There's almost no downside - it's weight reduction (hopefully), while allowing massive amounts of heat to vent itself, like Synolimit has experienced. A vented hood will always improve cooling efficiency at the speeds our cars experience.

A larger radiator and fan will help, but like I said - it's more of a "reactionary" solution to the problem, versus a "primary" approach of simply allowing the heat to not form as heat soak and get trapped in the first place. Another factor is also if people are okay with replacing the OEM hood - in that case, a larger rad / fans are required. But for race cars, you won't find one without hood/engine bay venting. ^^
Getting larger fans or more efficient fans will allow more airflow, which in most cases for cars, is beneficial. The OEM Radiator/Fan combination for some people simply cannot keep the car cool at full tilt, and that is where I'm assuming people are having issues, esp. with turbos.

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Chuck33079

Uprev adjusts the temp they turn on. The GTM fans move a lot more air than the stock ones.

Alstann, you're right on the vents being the best way to get hot air out of the engine bay. If there were a vented hood on the market I liked from a functional/aesthetic standpoint I'd start with that. I'm just not a huge fan of the options we have on that front, so I'm going to try adding the fans to the CSF radiator I've got, lowering the fan temperature more and running less antifreeze. If that isn't enough to keep temps stable, then ill start cutting holes.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

ANMVQ

I know my hood displaces a ton of heat during the summer.

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dmhenderson

I'm sure they do but I don't like those louvered vents on the Z.

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dmhenderson

Never fails that when I start one of these threads, I end up with more questions than I had when I started.

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Alstann

My 2c here:

I think that hood venting is the way to go for serious heat soak issues. It's a uphill battle trying to fight the motor by adding a larger radiator and higher CFM fan if the air is still getting trapped in the engine bay. I'd say that if you can live with the look of a louvered or vented hood, it's easily the best way to improve cooling efficiency of the car.

From a theoretical and practical standpoint, there are limits to using a combination of radiator and fan to cool a motor. One is the size aspect - larger radiator and larger fan is less space in the bay, and there is a limit to how large we can fit of both. Also, CFM doesn't necessarily mean cooler temps.

At my university, we build a small Formula-style car a competition hosted by SAE, called Formula SAE, and I'm part of the engine design team. It's a competition where universities build the car from the ground up - chassis, intake, exhaust, suspension, etc. For reference, the engine we use is a GSX-R 600cc. Google has lots of pictures of different cars - you'll get the idea if you search it. ^^

Something quite astounding that I've discovered while doing design on the cooling system is that the car (moving at an average of 30-45 mph on the track) is actually moving too FAST through the air, for achieving maximum cooling efficiency across the radiator. The solution to this problem is to design a sidepod (like the ones you see in Formula 1) that goes from small to big, back to small. This is to slow down the air. Of course, our motor is directly to the atmosphere, mounted in the rear.

The reason for this efficiency loss is as the air moves too quickly through the radiator, it builds up pressure behind and in front of the radiator, creating a boundary layer that lowers the true amount of air moving through the radiator. One might say: Why not use a higher flow fan to create a vacuum and move the air better? There are two reasons on a car: the first being that you want the air to spend a certain amount of time "inside" the radiator (not too slow where it's stopped, and not too fast that it creates the boundary layer), and second being that in most car engine bays, the bay is sealed enough that pressure builds up regardless. These speed values are different for every car, radiator design, hood design, grille design, etc.

But, of course I concede that a larger radiator and higher CFM fan usually increases cooling efficiency. I just know for a fact that venting the engine bay will, unless you are on the surface of the sun, always increase the cooling efficiency by letting nature do its work by letting heat escape. Also, with a larger radiator and larger fan, you also add weight to the car, and you change the dynamic of the water flow through the radiator, since the water pump is still stock. The reason we shoot for maximum efficiency, while still maintaining a reasonable safety factor, is literally, because racecar. Any amount of extra weight that isn't necessary in design, is making the car slower.

Also another thing to think about is that turbulent air and turbulent water through the radiator actually increases cooling efficiency.

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