Vented hoods and turbos
 

I thought I had kept an eye out for this but does anyone here with a vented hood have some pics of how this lines up with the turbo and motor? I want to see how rain may be able to get in and look at options to get all this heat up and out of the engine bay.

If this has been discussed, please point me in the right direction and kill this thread. :bonk:

Off the top of my head, I believe @Supermassive has a vented hood and P&L Turbo Kit.

Edit: Yes, he does

http://www.ft86club.com/forums/showthread.php?t=23457

http://farm9.staticflickr.com/8347/8...a5451996ca.jpg

Well I was hoping to see some others post here but it looks like @Supermassive is the only person with one.

I was looking more at these hoods with the vent almost (?) over the gap where our turbos are mounted.

Seibon DV
http://ft86speedfactory.com/seibon-c...od-dv-509.html

Seibon VS
http://ft86speedfactory.com/seibon-c...od-vs-510.html

The DV looks like it has better ventilation since there are two areas for the air to escape.
Either one would be painted to match the car.

I have the VS hood and it vents the heat really well. The vent basically sits right on top of the the turbo. Here's a pic I took after I I stalled the hood. For reference the drivers side is to the top of the pic and the front of the car is to the right of th pic. The gold at the bottom is the intake pipe and the turbo is towards the top. Hope this helps.

I'm about to cut a giant hole between the engine and radiator in my hood to extract excessive pressure in the engine bay during race conditions. It's more about allowing air to flow through the IC and radiator and then releasing that huge volume of air seen at high speeds. Given how well sealed up the bottom of the engine bay is for aerodynamics I'm seeing a lack of flow through while racing. Hood vents will allow the IC and radiator to work more effectively and you'll also end up with more front downforce.

The aftermarket hoods are vented conservatively which is fine for street guys and will still help substantially.

Thanks,
Phil Grabow

it seems that all after market hoods are carbon fiber..any aluminum ones or anything or am i going to have to cut up my own hood?

I can't remember if you're back in the country with your car again or not. But can you get a few pics further back for scale? Maybe leave a light from your phone on so it illuminates up from that area? Anything further back showing how the vent and engine line up would help a lot. :happy0180:

I am back in the country, but on leave in TX for another week. I'll get the pics you requested when I get home!

The only real concern I have with a vented hood at this point is sitting in traffic in the rain and getting my turbo blanket and wrapped downpipe wet. I would be willing to cut my OEM hood to add some vents if there was a vendor who made a kit with good directions and templates. :thumbsup:

What about hood spacers? I know people generally hate them as they leave a gap at the rear of the hood and looks like you just had an accident and didn't mend it correctly....

I would say the chances of anything getting wet underhood are less with hood spacers vs a vented hood though. Would be easy to test real world application with a trip to the hardware store for some nylon/delrin spacers and a temperature sensor

Would removing this weather strip allow some air to vent, similar to raising the hood?

I heard that removing that strip was one of the things the VCMC team did to help with the cooling of their Full Blown kit. I have been meaning to contact them to see exactly what they did.

Looks like it might be an alternative that doesn't alter appearance of stock hood, I wonder how big the gap would be compared to a spacer

If I remember correctly they just removed that entire plastic piece by the windshield. I'm not sure if that is what's holding the windshield wipers in place though, so removing it probably wouldn't be a good idea for a DD.

Raising the hood and/or removing the weather strip isn't going to help the cooling at speed. The base of the windshield is a high pressure area, so as speed you are going to force air back into the engine bay.

Since the engine bay is already a high pressure area, you want to use a low pressure area to "pull" the air from under hood out of the car. Looking at this velocity plot from Hancha Group, you'd want to have the vents in the red area of the hood. From what I've seen in other plots of theirs (on Miatas) the green is high pressure, low speed air. I'm sure they could shed much better light on this than me.

http://hanchagroup.files.wordpress.c...11/frs_001.png

As long as fresh air is entering then it would still be functional, its the lack of air movement (and heat) that people are concerned about
Also the green low pressure area is right at the hood cowl it appears, so it should create a low pressure area for air from the hood to vent from. Hopefully that will also mean the possibility of more air moving past your intercooler/radiator

It looks like the cowl area is less pressure than what's in front of the radiator, of course, but it'll never be as effective as hood vents underneath that red area on the hood, which will also result in more air through the radiator.

I agree hood vents would be most beneficial, just throwing out spacers as a possible alternative to those who may not want vents

Reviews seem mixed with spacers

I've had to resort to desperate measures while racing when dealing with cooling and underhood pressure. Now serious problems creep up when going 100 mph+ and on my STi pulling the rear rubber strip out did help a little (probably more at low speeds vs. high). In that application air doesn't not back flow from the windshield area into the engine like most said it should. I know this because fluids from the coolant overflow tank would spray onto the windshield. Ok there is a downside to removing that strip and one would be fluid on the windshield if the overflow coolant tank leaks a little (which it does) and two would be your fresh air vent on the passenger side would now be exposed to engine bay fumes.

Now I've also jig sawed huge holes in my hood at the track because I was getting black flagged because they thought my hood (carbon) was loose but it was just the massive pressure. After cutting the vent I noticed inreased cooling and more front end grip.

Now keep in mind this was a race application where speeds were seen over 160 mph. For the FRS/BRZ turbo guys I really think heat soak is more the real issue vs lack of airflow so if I was going to vent my hood I would do it like where an EVO hood is vented or that space between the radiator and the engine.

On my race car I have to increase airflow through the radiator at high speed as I'm overheating so I will likely cut a large opening as mentioned above, make a Gurney Flap for the leading edge, reverse Gurney forthe trailing edge, and paint some mesh to clean up the look. I did this to one of my STi hoods with god results and I'll see if I can dig up a picture.

real men saw holes in their hoods.

Well I think for street guys cutting a hole large enough so somebody could steal their turbo kit without popping the hood might not be the best choice. LOL! A good vented carbon hood or finding a louvered insert would be ideal.

My personal car......."because race car" who cares ;)

Does Seibon fall under "good vented carbon hood"?

Probably falls closer to "vented carbon hood", but I don't know that there are any better options. I will probably buy one eventually.

Street guys really don't need this much but real race cars do because of the high speeds and how much pressure builds up.

https://fbcdn-sphotos-c-a.akamaihd.n...31171562_n.jpg

https://sphotos-a.xx.fbcdn.net/hphot...11883770_n.jpg

Air can also be dumped out the sides of the bumper or underneath the car (least ideal).

Best I can tell, that plot is velocity, not pressure. That means the green area is slow moving air. Forcing more air under the hood isn't going to help very little. In theory its going to induce a little more front end lift (high pressure under hood, lower pressure on top). Another side effect is that adding pressure to the engine bay is going to make it harder for the radiator to do its job since it works on pressure differential. Raise the pressure behind the radiator and it lowers the difference of pressure between the two sides and less air is going to pass through the core.

I agree that sitting still or at low speeds, it might help out some, but at high speeds, you don't want to forcing more air under the hood (pressure has to go somewhere).

Makes sense. I had an issue with a vintage mustang where speeds over 75mph meant that you had little/no steering feel, and any steering input was basically ignored. The front end would actually lift due to air being trapped under the hood.... it was about as aerodynamic as a brick though.

On the composite undertray behind the aluminum skid plate there are actually vents cut into it. I wonder if thats where they want all the hot engine air to escape to, with airflow going through radiator/engine bay/and then out of those lower vents

Interesting. I was reading recently that the 2014 Corvette has the same design.

I often race with the Whelen Marsh Corvettes that run in Grand AM GT and USGT and they run a cowl type hood that vents at the windshield vs. most of the competition that vent more towards the front of the hood.

I would bet most street cars don't have vented hoods for better fuel efficiency and less drag. I was hoping I wasn't going to have to vent the hood since I don't have much front lift but the engine is just running too hot turbocharged while racing.

The '14 has a vent towards the front the way you do, so that the air movement over the hood at speed provides downforce on the front of the car.
Pretty cool technology that went into the car. They spent months on the scoops over the rear fenders that direct air to transmission (rear transaxle) cooler and another cooler I can't remember right now.

Oddly enough.. I engineer those big black plastic pieces by the windshield for a living (sadly), so maybe I could provide some insight.

Those are typically called cowl screens, or leaf screens.

These days, they have 4 main functions:
-Protect the wiper module system from the elements
-Project the HVAC system from debris injestion
-Visual appearance (a lot of customers prefer not to see raw metal and linkages from outside the car)
-Seal to the hood inner surface to reduce NVH and engine fumes.

Basically, if you don't care about your cabin air, your wiper system, or noisyness... Removing that piece will help quite a bit with engine cooling. Horrible idea for DD:thumbdown:. Great idea at the track :thumbsup:.

If my PD supercharger fits with this hood, i'll be going with it.

Always enjoyed the front end of STI's. This appeals to me.

i definitely need one for my turbo. it gets pretty hot under there in the florida heat.

Isn't there another hood out there like that made out of carbon? If i decide to super charge I think I may get something like that.

Except that you'll probably be better off with a vent than a scoop.

http://seiboncarbon.com/store/produc...l#!prettyPhoto


You might be thinking of the Seibon FA-style carbon fiber hood...

That's exactly what you do not want because now you have two sources trying to pressurize the engine. It actually doesn't even work at high speed to cool the intercooler on the STi. I actually cut a huge hole in my scoopat a race and had more downforce and much improved coolant temps.

Just remember air that goes in has to get out.

Oh thanks! I like that but with out the vents.

Would really like a hood along these lines:

http://www.reveuro.com/inventory/102...-m3-bmw.26.JPG

Vents could be a bit larger and perhaps placed differently, but something a bit classier than the Seibon.

I recently sold my CF hood and went back to the stock hood. As far as things getting wet when it rains...well i never had any issues, of course i have no exhaust wrap since i went with ceramic coating instead. The turbo blanke is also far enough forward that the vents don't allow any water to reach it on setups like the P&L and FB.

I can actually attest to this...the FR-S generates a ton of underhood pressure. When I was running my CF hood it was extremely noticeable because it would flex the sides of the hood up (near the wheel arches). At 160 there was about a 1-1/2 inch gap between the hood and the wheel arches...I decided to slow down since i didn't want the hood to break. That hood was also vented so it's definitely a science as to where venting should be to alleviate that pressure. I personally think that function fender vents would help substantially...but that would require some serious fabrication to make work well.