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

synolimit · 11-10-2013, 04:33 PM

Quote:

Originally Posted by dmhenderson

I'm not really sure whether this thread belongs in here or in the "body/exterior" forum but I figured I'd start here as I suspect I'm not alone. If a mod thinks this belongs elsewhere, please feel free to move it.

So unsurprisingly, I'm having radiant heat/heat soak issues especially when the car is pushed hard and I'm looking at more engine bay venting before I look into a bigger oil cooler/radiator/other cooling options whatever. I already have the vented fender liner from GTM so a hood scoop would be a nice way to get some air circulation going.

Thing is, I'm not crazy about the vented hood options I've seen posted here (carbon signal, seibon etc). I really don't like those diagonal vents as it kinda ruins the lines of the car - no offense intended, just my opinion.

I ran across this on my facebook feed (not my car):

...and it turns out this is a non-functional scoop - ugh. Is there a hood that looks like this or the old 350z vented hood style? I've been told modifying the stock hood (even with a fantastic metalworker) is a bad idea for several reasons.

Any ideas?

I wouldn't do a scoop only because I think a vent is better. Instead on bringing in ambient temps into the engine bay, I'd want the heat to get out of the engine bay faster/better.

dmhenderson · 11-10-2013, 04:36 PM

Quote:

Originally Posted by synolimit

I wouldn't do a scoop only because I think a vent is better. Instead on bringing in ambient temps into the engine bay, I'd want the heat to get out of the engine bay faster/better.

Well, I'd be leery about having the engine bay directly exposed to weather/debris/whatever even with that mesh there. I think I'd feel better with a combination of scoop/mesh.

Also, with my vented fender liners, a scoop would generate air circulation where a hole in the hood covered with mesh might not. Not an expert here or anything but I think I'll give my guys at D&V a call and see what they think.

synolimit · 11-10-2013, 04:37 PM

Quote:

Originally Posted by Chuck33079

Some NACA ducts like the gtr would work if we knew where to put them. I'm not convinced any of the aftermarket hood makers have done any more testing beyond "the vent looks cool right there". I'd hate to put the vent in the wrong place and make the situation worse.

From my testing and experience on mine, as far forward as possible! I don't know how the gtr works being so far back but I don't think they're a heat thing. I think they're a stabilizer or something because if you watch the making of the gtr on youtube they're insane with aerodynamics and drag etc etc.

synolimit · 11-10-2013, 04:41 PM

Quote:

Originally Posted by Chuck33079

Sure, you could have a good shop make some kind of scoop. I think the one in the pic is too far back. My guess is that the best solution from a function standpoint would be a vent with an extractor/louvers in front of the motor to give the air coming out the back of the radiator a place to go.

Bingo. New vette, all the evos, all up front before the motor to pull the radiator heat. It works for the same reason a bigger radiator will drop oil temps.

synolimit · 11-10-2013, 04:43 PM

Quote:

Originally Posted by dmhenderson

I like that concept and placement but I still think I'd want a scoop or something on top of that so that if I get caught in weather, the engine bay isn't directly exposed.

Evos have done this forever, no issues with them year round. An engine bay is basically water tight. Nothing will happen but surface rust or corrosion on aluminium parts. And that happens even with closed hoods.

Chuck33079 · 11-10-2013, 04:46 PM

The problem on the Z is how little room there is between the motor and radiator. The air almost has to make a 90 degree turn to go out a vent placed there on the hood. A deflector on the timing cover to split the airflow to either side and two vents basically over where the intake pipes run may be more useful. Until we get some guys willing to tape yarn all over their hoods to check airflow at speed, we're just guessing.

synolimit · 11-10-2013, 04:47 PM

Quote:

Originally Posted by dmhenderson

Well, I'd be leery about having the engine bay directly exposed to weather/debris/whatever even with that mesh there. I think I'd feel better with a combination of scoop/mesh.

Also, with my vented fender liners, a scoop would generate air circulation where a hole in the hood covered with mesh might not. Not an expert here or anything but I think I'll give my guys at D&V a call and see what they think.

How is the fender vented? Behind fenders isn't the engine bay, it's normally the side of the fire wall and the reenforced impact rails the motor sits in between. If there is I direct link, adding a scoop doesn't mean air will enter and leave. Unless you can wind tunnel test, you'll have no idea whats going on and you could be killing your aero.

Chuck33079 · 11-10-2013, 04:50 PM

The fender vents aren't going to address the main issue, which is getting the hot air passing out of the intercooler/radiator out of the engine bay. The only thing the fender vent does is give the air exiting your oil cooler a place to go.

The scoop may also make things worse. If you're pressurizing the engine bay through the scoop, you may stall the air coming through the radiator.

dmhenderson · 11-10-2013, 04:51 PM

This is likely a problem I will have to wait until spring to tackle. Kinda hoping a vendor figures this out and offers a solution that isn't a gaudy CF louvered hood before then.

dmhenderson · 11-10-2013, 04:52 PM

Quote:

Originally Posted by Chuck33079

The fender vents aren't going to address the main issue, which is getting the hot air passing out of the intercooler/radiator out of the engine bay. The only thing the fender vent does is give the air exiting your oil cooler a place to go.

yeah that's what I was thinking. Scoop forcing air downward over the engine means better airflow over the oil cooler and out the fender vents. That said, I'm not sure it would actually work but it would make sense.

Chuck33079 · 11-10-2013, 04:53 PM

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

synolimit · 11-10-2013, 04:54 PM

Quote:

Originally Posted by Chuck33079

The problem on the Z is how little room there is between the motor and radiator. The air almost has to make a 90 degree turn to go out a vent placed there on the hood. A deflector on the timing cover to split the airflow to either side and two vents basically over where the intake pipes run may be more useful. Until we get some guys willing to tape yarn all over their hoods to check airflow at speed, we're just guessing.

Doesn't matter, it works same way the air hits the motor and has to 90* down under the car. Airs light, it can change direction fast just like a stillen CAI bends. Heat rises and the hot air hitting the engine has no place to go but up or down and under the car. Both of which get the heat moving and out with a properly placed vent. And I did the yarn test on mine.

Chuck33079 · 11-10-2013, 04:55 PM

Quote:

Originally Posted by dmhenderson

yeah that's what I was thinking. Scoop forcing air downward over the engine means better airflow over the oil cooler and out the fender vents. That said, I'm not sure it would actually work but it would make sense.

Airflow in that direction may interfere with the airflow through the radiator. You want air being pulled out of the engine bay, not going in.

dmhenderson · 11-10-2013, 04:55 PM

Quote:

Originally Posted by Chuck33079

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

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

Chuck33079 · 11-10-2013, 04:56 PM

Quote:

Originally Posted by synolimit

Doesn't matter, it works same way the air hits the motor and has to 90* down under the car. Airs light, it can change direction fast just like a stillen CAI bends. Heat rises and the hot air hitting the engine has no place to go but up or down and under the car. Both of which get the heat moving and out with a properly placed vent. And I did the yarn test on mine.

The gentler the change of direction, the better the flow.

11-10-2013, 04:46 PM	#21 (permalink)
Chuck33079 A True Z Fanatic Join Date: Nov 2011 Location: Houston Posts: 12,265 Drives: 2011 370ztt Rep Power: 29538	The problem on the Z is how little room there is between the motor and radiator. The air almost has to make a 90 degree turn to go out a vent placed there on the hood. A deflector on the timing cover to split the airflow to either side and two vents basically over where the intake pipes run may be more useful. Until we get some guys willing to tape yarn all over their hoods to check airflow at speed, we're just guessing. __________________ 2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

11-10-2013, 04:50 PM	#23 (permalink)
Chuck33079 A True Z Fanatic Join Date: Nov 2011 Location: Houston Posts: 12,265 Drives: 2011 370ztt Rep Power: 29538	Heat soak - vented hood options that are not "louvered" The fender vents aren't going to address the main issue, which is getting the hot air passing out of the intercooler/radiator out of the engine bay. The only thing the fender vent does is give the air exiting your oil cooler a place to go. The scoop may also make things worse. If you're pressurizing the engine bay through the scoop, you may stall the air coming through the radiator. luigi90210 and snowsurfdirtx like this. __________________ 2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

11-10-2013, 04:51 PM	#24 (permalink)
dmhenderson A True Z Fanatic Join Date: Feb 2011 Location: Maryland Posts: 5,930 Drives: AWD TT 370z Rep Power: 26	This is likely a problem I will have to wait until spring to tackle. Kinda hoping a vendor figures this out and offers a solution that isn't a gaudy CF louvered hood before then. __________________

11-10-2013, 04:53 PM	#26 (permalink)
Chuck33079 A True Z Fanatic Join Date: Nov 2011 Location: Houston Posts: 12,265 Drives: 2011 370ztt Rep Power: 29538	Maybe some kind of extractor setup on the under panel? Bring the air out the bottom? __________________ 2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

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