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Old 06-01-2011, 04:04 AM   #1
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Center Radiator Question

getting ready to put a center radiator in my car. when the air exists the center radiator, where does it go? the online installations i've looked at seem to ignore this question.....

i'm considering installing the duct for the turbo (#18 in the photo below) and venting the air through some new holes i'll cut under the nose. has anyone done this? anyone understand where the airflow is directed in the absence of this duct?

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Old 06-01-2011, 04:28 AM   #2
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I thought it's well documented that the center radiator causes more drag.

9x7 don't have it AFAIK.
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Old 06-01-2011, 04:38 AM   #3
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Quote:
Originally Posted by ekam
I thought it's well documented that the center radiator causes more drag.

9x7 don't have it AFAIK.

it's also well documented that it causes more cooling.

the standard radiators on the 2.5L / 2.7L cars are BARELY adequate at the track w/ a stock motor. i have shoveled a 3.4L in my car & the temps spike up to 225 after thirteen minutes at full tilt in 80F weather. i need more cooling.
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Old 06-01-2011, 06:59 AM   #4
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Vent it up if possible with a hood vent and ducting ala 996 GT3. The less air under the car the better it will stick. This one is for a 997 but I have seen some on a 996:
http://cgi.ebay.com/ebaymotors/NEW-GENUINE-PORSCHE-GT3-FRONT-BUMPER-CENTER-VENT-GRILLE-/320671856356
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Old 06-01-2011, 07:02 AM   #5
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Vent it up if possible with a hood vent and ducting ala 996 GT3. The less air under the car the better it will stick.
yeah, i was considering that.....

still curious as to where the S vents this radiator. it looks like air exits right into metal....
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Old 06-01-2011, 07:17 AM   #6
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I think the Box S is open to the sides behind the center rad so it just vents through the side radiator ducting. Not ideal but clean and simple. Looking at Pedro's DIY he addresses the incoming air duct but not ducting after the rad. I suspect it goes down and to the sides.
http://www.pedrosgarage.com/Site_3/Install_3rd_Radiator_%26_Coolant_System_Bleeding_I nstructions.html
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Old 06-01-2011, 07:32 AM   #7
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On my 3.2 S there is a plastic thing behind the center radiator that channels the air left and right.

I always thought that this was lame in that it does not allow the air to pass through the radiator becasue there is very little room behind it.

Installing the GT air dam and cutting a hole in the bumper is the proper fix I believe. As a short cut I was going to add high RPM electric fans to the back to draw the air though.
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Old 06-01-2011, 07:53 AM   #8
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got it; thanks. oddly i can't find the part number in the catalog; no picture of it anywhere.

i am trying to make up my mind. i may vent it sideways, but open up the wheel well liners like in the photo below.

FYI, the normal radiators exit just in front of the tires & under the car. there are little flaps that try to guide the air around the tire & to the outside; not sure how effective they are.....

photo is courtesy of hergesheimer motorsports.
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Old 06-01-2011, 08:13 AM   #9
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Quote:
Originally Posted by insite
got it; thanks. oddly i can't find the part number in the catalog; no picture of it anywhere.

i am trying to make up my mind. i may vent it sideways, but open up the wheel well liners like in the photo below.

FYI, the normal radiators exit just in front of the tires & under the car. there are little flaps that try to guide the air around the tire & to the outside; not sure how effective they are.....

photo is courtesy of hergesheimer motorsports.
That is Eric Oviatt's BSR car. It is very well sorted and he is very quick. My only concern with wheel well venting is the possibility of damage if a tire picks up something nasty and hurls it through the rads. If/when I add a 3rd rad I will probably just keep it simple like the Box S but I have to admit I like the look of a GT3RS vented hood. Form follows function. Here is a wind tunnel shot:
http://i279.photobucket.com/albums/kk144/TB993tt/windtunnel.jpg
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Old 06-01-2011, 08:17 AM   #10
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great photo. i've got the GT3 nose without the venting, unfortunately. i've seen people cut vents into it, but i kind of like the way my car looks.....
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Old 06-01-2011, 08:40 AM   #11
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here is a picture of the plastic thing on my car. ( the pictures are from the net- not my car) it channels the air side and down. pretty weak if you ask me.
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Old 06-01-2011, 09:29 AM   #12
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got it. i think that is the part in my post 1 diagram. oddly, it shows up no where in the boxster PET....

i'd rather vent throught the nose, but i may go this route for now.
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Old 06-01-2011, 09:59 AM   #13
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Quote:
Originally Posted by insite
it's also well documented that it causes more cooling.

the standard radiators on the 2.5L / 2.7L cars are BARELY adequate at the track w/ a stock motor. i have shoveled a 3.4L in my car & the temps spike up to 225 after thirteen minutes at full tilt in 80F weather. i need more cooling.
Just as a side note .....yes any vent causes drag. I am wondering if my 60% flow through radiator mesh would reduce drag at higher speeds as more of the air flow is directed up over the car instead of being caught by the front openings.
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Old 06-01-2011, 10:45 AM   #14
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to reiterate other posters and support the images, the 986/996 vent the centre downwards. the gt3 vents upwards. it's not just a simple matter of putting the gt3 vent thingy on your bumper ($79, $350 if you want it in CF to save .5 oz and get that cool japanese look); the centre rad is actually tilted back on the 986/996 install kit such that the top of the rad is pretty much flush with the forward bulkhead - nowhere for the air to go but down. if you want to vent up, you can get the gt3 kit, but i'm uncertain if the attachment points are the same, and i think the kit is an order of magnatude more expensive. or, some have taken the 986 kit and turned it upside down to get the rad to angle the proper way (check out the thread on the subaru engine conversion). again, uncertain if all the attachment points still work. also, you may have issues with rad hose length, the plastic duct on the front of the rad no longer meets the bumper cover properly, and the bumper interferes with airflow (some remove the bumper alltogether). there may also be fitment issues with the two side radiator duct assemblies.

more of a project than you would think; i cannot understand why porsche would do it that way ...
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Old 06-01-2011, 11:03 AM   #15
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Insite you are correct, you need the center radiator if you running at the track with more than warm temperatures.

I installed the center rad a couple of years ago and had to cut a couple of rectangular holes on the bottom of the bumper like the tiptronic cars do

Also with a dremel tool I cut open (removed material) from the wheel well splash guard, right between the reinforcing web contours casted on the plastic, it seems that some P cars had these holes punched at the factory, this allows more air to flow from the radiators as well.

I had mine for 2 1/2 years and never had any issues at Willow's cozy 115 F... (yes, on the shade)

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Old 06-01-2011, 11:29 AM   #16
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re cutting the wheel well liners, my understanding was that the side rads do vent down, but with the intent to send the air to the brake ducts?
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Old 06-01-2011, 08:46 PM   #17
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Quote:
Originally Posted by The Radium King
re cutting the wheel well liners, my understanding was that the side rads do vent down, but with the intent to send the air to the brake ducts?
Radium,
Some P cars come with the vent holes already cut from the factory (punched) and other models (like mine) didn't, I remember someone mentioning the reason behind but that was almost 3 years ago...
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Old 06-02-2011, 05:21 PM   #18
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My 3.8 stays plenty cool with the stock S cooling setup, but in hindsight, I really do wish that I had added the ducting and made the cutouts in the bumper.....
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Old 06-06-2011, 03:08 PM   #19
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Quote:
Originally Posted by ekam
I thought it's well documented that the center radiator causes more drag.

9x7 don't have it AFAIK.
Here's the parts for sale with pic's on E-bay:http://cgi.ebay.com/ebaymotors/Porsche-997-987-Center-Radiator-KIT-_W0QQcmdZViewItemQQhashZitem5ad95b1284QQitemZ39019 3681028QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries
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Old 06-06-2011, 05:50 PM   #20
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i checked under my car; the aerokit II GT3 style nose does indeed have the cutouts that vent out the bottom. i ordered the turbo ducting & will go that route for now.....

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