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Posted by: Stonepilot Jan 4 2012, 02:07 PM

Anybody done one of these? Got a picture would love to see what it looks like? Thank you

Posted by: SirAndy Jan 4 2012, 02:16 PM

Scooping for what exactly?

Posted by: Stonepilot Jan 4 2012, 02:20 PM

Air across a radiator

Posted by: wingnut86 Jan 4 2012, 02:21 PM

Stonepilot,

Are you thinking of just visual with a blocking plate in the hole or is this for oil cooling?

The reason I ask is due to not many going top-scoop mount as it creates flow issues over that streamlined hood of ours

Most AX'rs, Racers and Street Demons use a vented lower valance up front or something less visual.

Good luck if you find something and please share it here, as I for one have never seen one...

Posted by: SirAndy Jan 4 2012, 02:24 PM

The hood is too high for a intake scoop.

Usually, you run the intake though a opening in and behind the bumper (See my avatar).

There are several ways for the air to exit and i do prefer the "out the hood" vent. Neither the "original Porsche way" (out the bottom) as well as the "v8 way" (out the fender wells) appeal to me.
The first adds a lot of hot air under the car, the second adds a lot of hot air onto the front brakes.

Do a search here, there are several cars that have gone the exit out the hood route. It's crucial to have a front facing "lip" on the exit to help with air-flow.

Posted by: SirAndy Jan 4 2012, 02:27 PM

I'm currently venting out the bottom, but that's temporary until i can find the time to fabricate a nice shroud for venting out the hood.

http://www.914world.com/bbs2/index.php?s=&showtopic=44700&view=findpost&p=893543

Posted by: bfrymire Jan 4 2012, 06:32 PM

Look for Britain's build thread on adding a suby powerplant to the 914. He has a hood exit for the radiator using louvers.

-- brett

Posted by: JmuRiz Jan 4 2012, 07:16 PM

Now you're talking...venting out the hood is the best way, as long as you don't mind poising cargo space.

I'm trying to think of a way to do a front cooler w/o taking up much/if any cargo space up front...haven't found one yet though.

Posted by: SirAndy Jan 4 2012, 07:32 PM

Look at some newer model Porsche's. They use a very steep angle right after the cooler that goes almost straight up.


In my case, i'm going to make the shroud a two piece part so when you open the hood, you still have access to the space behind the shroud. Should be enough for a toolbox and other assorted items.
The spare tire is already mounted in the rear trunk. I'm going to leave it a full-size spare but i'll be going down in rim diameter. Right now my spare is a 7" cookie cutter with a 215 tire. A 5.5" with a tire somewhere around 175 should be plenty for a spare.

Posted by: Stonepilot Jan 5 2012, 06:53 AM

could you raise the hood an inch up near the windshield and build a vent under the hood to take the air coming thru the radiator out over the windsheild. of course the air coming in is under the car. is the air coming off the radiator that hot?

Posted by: Andyrew Jan 5 2012, 07:35 AM

What engine will you be running?

Posted by: Stonepilot Jan 5 2012, 07:51 AM

Id like an EJ20 but any 6 will do, maybe something new

Posted by: rnellums Jan 5 2012, 08:22 AM

The problem there is that the base of the windshield is a high pressure zone. It isnt as high as the front of the car where your inlet will be, but you won't get as much airflow as if you vent to a low pressure area.

When I do my conversion I think I will vent to the wheel wells. I still need to do the calculations, but I think the relative heat coming out of the vents should be far less than the temperature of the brakes under heavy use.

Posted by: bulitt Jan 5 2012, 09:11 AM

Some pics-

Ferrari 308, 512bbi used louvered grills-



Shelby Daytona- With lip Andy mentioned.



Ford GT-40



Jag XKE used louvers, Dodge viper also louvers.

Posted by: brant Jan 5 2012, 09:22 AM

I've ran a vented hood on my oil cooler for 15 or so years
its all steel and pictured in my street car signature below

Posted by: Britain Smith Jan 5 2012, 12:55 PM

Vented Carbon Fiber Louvers...works awesome.





-Britain

Posted by: SirAndy Jan 5 2012, 12:59 PM

That's exactly what i want to do!

Well, not the big hole in the hood, but what you had before that. A shroud going up with louvers on the hood for the exit.

Posted by: Stonepilot Jan 5 2012, 02:09 PM

very nice thats what I was talking about. thank you

Posted by: Andyrew Jan 5 2012, 08:49 PM

With a small engine like that, you could put a small radiator in the front of the trunk, or in with the body and then exhaust it out the front of the hood like the new porsche's. Then guess what, You still have a front trunk!

Posted by: wingnut86 Jan 5 2012, 09:01 PM

Go Subie and buy this gents hood!

Group discount?

Posted by: wingnut86 Jan 5 2012, 09:03 PM

Hand made or re-purposed?

Posted by: kg6dxn Jan 5 2012, 11:48 PM

The hot air on the brakes at 180-190F is cooler than hot brakes. It can actually act as cooling on the track when you are on the brakes a lot.

I think cooling through the fender wells is the most proven cooling design for a street car.

Posted by: Britain Smith Jan 5 2012, 11:53 PM

I got those vents from here:

http://www.genesisparts.com/index.cfm?tpc=Genesis_Carbon_Fiber_Hood_Louvers&form_prod_id=1_8&action=product

They weren't cheap, but serve the purpose.

I am not a fan of the air vents in the wheel wells, that is the last place I want air to go at high speed.

-Britain

Posted by: szuccaro Jan 6 2012, 12:01 AM

Here's my idea... taken from the late model turbo T-bird... Steve


Attached image(s)

Posted by: szuccaro Jan 6 2012, 12:05 AM

and applied to the side, looks like this.



Attached image(s)

Posted by: brant Jan 6 2012, 12:10 AM

do you have a cooler under there?...

Posted by: szuccaro Jan 6 2012, 12:53 AM

purely non-functional

Posted by: Elliot Cannon Jan 6 2012, 01:33 AM

It looks like their function is to cause aerodynamic drag.

Posted by: SirAndy Jan 6 2012, 01:39 AM

Proven by what exactly? I'd rather have fresh air to cool my brakes.

Posted by: Stonepilot Jan 6 2012, 06:22 AM

nice looking!

Posted by: pcar916 Jan 6 2012, 08:04 AM

Here's mine. It's illegal in SCCA track events though.



Good luck

Posted by: wingnut86 Jan 6 2012, 08:10 AM

I looked through the rules previously, but, why do they say no to that design?

are there other in-hood venting designs they say yes to?

Posted by: brant Jan 6 2012, 09:25 AM

cross post from my street car thread:




Attached thumbnail(s)


Attached image(s)

Posted by: pcar916 Jan 6 2012, 09:41 AM

It wasn't part of the original design of the car, and they consider it an air diverting structure, as if air through a big cooler would add downforce to the front of the car.
It also wasn't part of the original design of the car. To be fair it's been years since I looked into it so this is now second hand info to me. Anyone who knows this has changed can chime away.

I first evacuated the exhaust under the car but not only did it not cool the oil very well (inlet too small... my design error) but I figured it was simply heating air back to the engine. The 993 engine needs a full-time cooler since engine cooler behind cylinder #6 was deleted.

Posted by: SirAndy Jan 6 2012, 01:14 PM

If i recall correctly, the guy that did all the air flow tests on modified 914 chassis a while back reported a significant increase in downforce with a hood vent.

From my armchair physics perspective, that would make sense.

Posted by: Andyrew Jan 6 2012, 01:16 PM

^ I would agree with this as well.

It might not make much of a difference at 60mph, but at 100mph it would probably be fairly noticeable.

Posted by: Britain Smith Jan 6 2012, 01:21 PM

I have been thru the fight with the SCCA guys on hood venting, what I did with the louvers was the best I could do within the rules for Autocross. There can be no actual ducting underneath either.

-Britain

Posted by: SirAndy Jan 6 2012, 02:29 PM

On that note, one of the 911 guys that runs in the Toyo spec class with PRC here locally showed up with a hood exit vent for his front mounted oil cooler last summer.
(Pretty well known guy too)

When i asked the officials about the obvious rule violation, i got the following answer:

"He's too slow anyways. Once he starts winning, we'll worry about that."


Gotta love those guys!

Posted by: bulitt Jan 6 2012, 03:09 PM

I'm thinking you could close off the front half of your exit opening and not lose much airflow?

Posted by: MDG Jan 6 2012, 03:10 PM

Hood scoop from the lastest Ferrari GTO concept on a random pic of a 914

Posted by: brant Jan 6 2012, 03:13 PM

My front opening is smaller than the liscense plate
I leave the plate on most of the time and only pull the plate when I need the cooling... (ie: heat of the summer, or track time)

I've use the exact (and acutal) same cooler in three different exit configurations
each one opened up and increased the exit size, and correspondingly dropped the oil temperature

this one has a HUGE exit for a very small cooler and is 20degrees F cooler oil temps on the track than my most restrictive experiment (same cooler, same car, same motor, different day)

I agree with the old rule of thumb about using 2x the exit size of your cooler entrance size.... (that hot air expands and a good exit draws more air through the cooler)

Posted by: SirAndy Jan 6 2012, 03:53 PM

One would think that with a louvered cover (even if only partially covering that huge hole) you could get pretty close to the same actual open surface but with a much better visual result.

Posted by: MDG Jan 6 2012, 04:21 PM

Looks like he made some mods

Posted by: wingnut86 Jan 6 2012, 04:25 PM

Hey,

I thought Danny Bonaducci from "The Partridge Family" had lost his license on crack.

But there he is behind the wheel.

Posted by: pt_700 Jan 6 2012, 04:36 PM

i wonder if those extraction vents on the hood might feed hot air into the cockpit with the top off on warm days?

do any of the posters with wheel well vents drive in the rain or dusty conditions? might this make the front trunk dirtier?

Posted by: SirAndy Jan 6 2012, 05:33 PM

There is no *might* about it. Yes, even with the screens used on some, there's a lot of dirt in the front trunk.

As for the hot air over the windshield, yes, you can feel it but it disperses pretty quickly.
One would have to run a couple of tests with a few sensors around the car to get exact numbers.

However, my point still stands. I'd rather have the air up and away than under the car where it will create additional lift.
Not much of a problem for street driving, but at the track, you'll want all the help you can get.

A 914 can get pretty "light" above ~120mph ...

Posted by: PeeGreen 914 Jan 6 2012, 05:51 PM

The last thing I would think you would want to do is make it any lighter in the front by adding lift. Going around a sweeping bend at 100+ it feels light enough without the added lift.