Mine.
 

CarbonSignal's vented hood

https://fbcdn-sphotos-b-a.akamaihd.n...80824645_n.jpg

https://fbcdn-sphotos-e-a.akamaihd.n...06543483_n.jpg

https://fbcdn-sphotos-b-a.akamaihd.n...39176021_n.jpg

Has anyone (DIY or commercial) actually analyzed the pressure and airflow situation to figure out the best location and flow direction for vents? There should be good pressure under there from the radiator outflow, it's just a question of where the best place to exhaust it is. Are the GTR-style NACA ducts intended to draw air out and forward via the airflow that likely reverses at the base of the windshield? The CarbonSignal vents (rearward flowing up the sides) could work, too, but it would just be nice to see some real pressure/flow proof.

Just run no hood. :p

I have access to a Fluke thermal imaging camera at work. When get my car back from the body shop I'll ask one of the guys to grab some images of my hood with and without the fan running. Temps should be in the 90s, so I'm curious to see how much hot air is flowing out of the vents. I'm just hoping for something lol.

No, we haven't and we should. Behind the radiator is probably the highest pressure area that we want to release. Above the headers is the hottest area but there isn't much airflow going up from there. Vents won't do a whole lot to cool the intake tubes, but the hot metal everyone with G3s runs robs power.

Someone with a vented hood needs to tape a bunch of short pieces of yarn around the vents and go for a drive. That way we can see if the vents are working. I'm concerned that some of the vents on the hood are too close to the windshield and outside air is getting forced in rather than the other way around.

That's why mine are wrapped in heat shielding :)

Just reporting no issues with my vis and no problems in the rain. Not sure how they are at taking in cold air but you can see hot air escaping

Well, hot air escaping is the only goal here. The "cold" air intake for the engine bay is through the nose and radiator. We just want to give the air coming out the backside of the radiator (out of the fans) a place to vent/suck out of the bay on the hood somewhere. It improves the overall flow rate through the radiator because you're relieving that buildup of high pressure when it all hits the bay and has nowhere good to vent to.

The general "makes basic sense on most cars" point of view is that the best place to vent it is as near as possible to the front/center of the hood right behind the radiator fans, because up high in the rear there's usually a reverse flow of air pushing back forward down the hood (it rolls over at the base of the windshield). Without real data on this exact car, though, it's hard to know for sure. Any kind of venting probably helps, but it would be nice to find a design we know is optimal before cutting up hoods.

Wstar, if I pick up the Seibon TS hood I will make some time to come by and we can do some testing. Be it crude paper & tape or other stuff, plus you know my engine bay makes plenty of heat so will be a good test. :tup:

My car is still at the body shop, but hopefully it'll be done tomorrow. Here's the Aero Jacket one off OEM hood modification. The shop is going to look for an aluminum mesh grill, so the car will go back to get the grill cut and put on at a later date.

http://www.the370z.com/attachment.ph...1&d=1374618635
http://www.the370z.com/attachment.ph...1&d=1374618635
http://www.the370z.com/attachment.ph...1&d=1374618644

Looks good.

Lets say this happens. The hot air doesn't come out but it never did before either. But if you're pushing ambient temp air down into the engine bay then engine bay temps should drop! Whether the hot airs pulled out, or ambients pushed in, we still are achieve a desired goal of getting a lower temp.

The problem is when you have high pressure air coming in from the back side of the hood, it can stall the air coming in through the grill, reducing airflow through the radiator.

That's at speed, though. At a stop, it'll still vent hot air. That's why we need to check which direction air is moving at speed.

The goal is increasing the airflow through the radiator by giving the hot air coming out of the radiator somewhere to go. With no hood vents you tend to just build up pressure in the engine bay and that restricts radiator flow. If you install hood vents in the most wrong way possible, you'll end up pushing cold air *into* the hood through those vents, which will counterintuitively make the car run hotter because you're making the pressure situation worse (because radiator airflow is vastly more important than just stuffing cold air randomly into the bay). A rearward-facing vent that's too close to the windshield can be bad that way, because there's usually a flow of air that rolls under at the base of the windshield and moves forward along the upper part of the hood. Each car is a little different though, and it's hard to say without careful analysis.

Well I've seen a few gtr vents and custom vents and no reports of horrible coolant temp issues so I think we're all good. I mean has anyone here even got their coolant dots over half way? Only thing I've noticed about our car in respect to you saying about the window and air is our car is pretty sealed up. I've never owned a car (which is about 30) that's had so much rubber sealing all the way around it.

Stock or NA cars aren't really in dire need of this, it's more for the FI guys since we've got a big *** intercooler stuffed in front of the radiator. We don't need to hamper airflow any more than we already have. If it's over 100 and I've been beating on the car and then get stuck in traffic with the ac on full blast, I can get the temp gauge to move a couple of dots. The OEM gauge isn't going to be accurate enough to show anything but a drastic difference. We really need someone with a water temp gauge. DIGI's vents look like they're in the area where I'd think you'd get the most hot air being extracted at speed. He's got access to a thermal cam, so that should let us see airflow at idle. Unfortunately we don't have many options to test airflow at speed other than short pieces of string all over the hood. It works, but it's a pain in the ***.

Can we get pics from the underside of the hood?

I'll take some pics after getting the car back. The tech definitely cleaned it up nicely.

The base of the windshield is a high pressure area. That's why the old cowl induction hoods, the L88 hoods, the Z28 hoods and the Trans Am hoods, just to name a few, all had their cold air intakes there. Using that high pressure area to push cold air into the carb. If you're thinking of using that area to vent a hood to release heat. It won't work. ;)

Man, that looks really good. Nice simple lines and looks like it will be functional. Thank you for posting this photo. Found my next project..:bowrofl:

Thanks... haha you missed a post in between of the painted hood. :)
http://www.the370z.com/2415734-post51.html

That is perfect.. Looks factory..:happydance:

Sweet! That is one hood I would run on my car. Now to find someone to do the work for me. :shakes head:

Thanks, all. I'm not sure I even need a thermal camera since it's easy to test with the cooling fans running. The front most vent doesn't flow much air at all, but the one in the middle vents lots of air. That should give you guys a ball park.

Overall, I'm liking these vents especially the middle one. If you guys have Aero Jacket cut them out for you, be prepared for lots of prep work to make it look clean. The tech at the body shop did an excellent job cleaning things up and adding additional reinforcements. It should be further improved once grills are added.

http://www.the370z.com/attachment.ph...1&d=1374720562
http://www.the370z.com/attachment.ph...1&d=1374720562
http://www.the370z.com/attachment.ph...1&d=1374720571

Can't we live log the coolant temps? Isn't there apps too for iPads and stuff to view everything?

Yeah you can use Torque on android. My RaceKeeper datalogger tracks coolant temps throughout my track sessions, too (well, when I don't have a bad SD card or some other tech issue holding it up, as was the case the past time out). Even NA engines can use a little more airflow through the radiator if they can get it, when doing track events in the TX summer heat. Radiator airflow correlates with oil cooler airflow too, since it's all in the same air path.

I wouldn't get Aero Jacket to make the hood for me after seeing what they gave you to work with. Your tech did a great job cleaning up their work. Looks great!

It's a one off kind of thing. I ended up spend way too much on this hood after all is said and done. Issues keep piling up... now my DVD HU is dead after picking up the car. No guarantee the shop is going to cover it.

Yeah but I assume you mean you're looking at the coolant fan flow with the car sitting at a stop. Everything can change pretty dramatically once the aero effects come into play at speed (80mph wind hitting the front grill, flowing over the car in some unknown shape, bouncing off the windshield, etc).

Ideally we'd wind-tunnel this stuff, but that's pretty unlikely to happen given the costs. The yarn thing is really the way to go for at least understanding the airflow on the outside skin of the hood. Differential pressure gauges can tell us for sure where the pressure buildups happen both under and over the hood. Between those two we can probably make some pretty good approximate design choices.

To me, the real tragedy is that the community will have to eventually do this itself instead of some manufacturer doing it with their own resources and time. The ratio of vented hoods being sold by vendors to vendors actually doing research to make sure they're effective is sad.

That ratio is directly in line with the ratio of people who want a vented hood because it looks cool to people who want a correctly designed vented hood. Digi's is one of the few I've seen where the vents look like they're in the right place and shaped right.

Well, sure, I could've restated my opinion as a statement about ratios of types of owners too, and I might've done it with sharper words than that, but then the whole forums would come down on top of my head :) There's nothing wrong with owning/driving a sportscar just for the look-and-feel, but it starts bugging when people throw so many hours and dollars into modding the hell out it with very functional-sounding parts any have no idea whether they're functional or counter-productive...

I'm pretty happy with the results. It's definitely better than nothing, and it doesn't look too ricey either. I still prefer this over a CF hood, unless it's a true composite (super crazy expensive). My car is stuck in the garage to let the paint fully cure before getting the rock guard installed. I'll keep you guys posted once the car is back on the road.

That finished hood looks absolutey excellent! Surprising after I saw the way it arrived to you. Looks like it'll be very functional unlike the hoods where the vents are out at the sides, instead of the middle where they would extract hot air after the radiator.

I wanna hook my iPad up. What's the best program and cable and easy plug and play?

I understand.

Hopefully you get your head unit sorted out ok. Have you checked the fuses?

Yup. I pulled it apart to check the fuse behind the unit and the power connections. I've got +12V, IGN, and fuse is fine. Unit still dead with no blinky red light. The shop says this stuff is over their head and they want me to get a professional opinion from a car audio shop to prove that interior cleaning damaged the unit.

Guess being a Computer/Electrical engineer isn't enough to convince them. :P

I don't know, I don't use iThings in general, usually. A google search might tell you. For Android I prefer the bluetooth OBD-II dongle from Kiwi. I think iThing people tend to use the Wifi version because of some Bluetooth software issue Apples has about generic data protocols. No idea what app they use with it.

That sucks. :ugh2:

Seibon TS Hood
 

http://farm4.staticflickr.com/3753/1...062c50a2dd.jpg

Just installed this 2 weeks ago. Absolutely love it! You can feel the heat pouring out of the car when it's stopped. It probably helps my CAI's the most from heat soak. Beyond that it looks bad *** IMHO