Another cooling-enhancement idea - roof scoop?

[widebody911]

The guy who is making the cab hardtop mold for me has a mold for a GT-1 style roof scoop that he did a one-off for another customer. I don't have pix, but I can sorta describe it: the scoop starts above the windshield, runs down the roof, over the back window and feeds directly into the engine grille of a turbo/GT2 type engine lid. He 'lent' me the mold, and I qualify that verb because it seems he doesn't have any use ffor it. I was thinking of laying one up just to see what it would look like.

My question is, does it seem like this would be a valid way to enhance cooling? The scoop opening is 15" wide by 3" tall at the highest point

I have pix of the mold, but I think they're useless for showing the shape of the part.

[Overpaid Slacker]

You'd think they'd have to help somewhat, as long as you're moving forward; and they look the absolute business.

JP

[89turbocabmike]

They definitely make a car look like a serious racer if the rest of the car is up to it. Otherwise I'm afraid it would look a bit like those scoops they use to add to vw bus' and bugs, like a band-aid! I'm trying to think what you would cool with that: Transmission cooler, intercooler(for a water/air one too.), oil cooler. It's obviously good for a car always running at speed and not running a aux. fan)

Love your projects Thom! Still thinking about a hard top if I can't find a factory one.

[project 911]

Here ya go-

[widebody911]

I totally forgot about that ebay beast!

[jester911]

I have been kicking around ideas about doing what they do in the newer 911's with the direct induction from the rear spoiler to the intake.

Fresh air is good air

[project 911]

I thought this idea was interesting.

[jyl]

Stylistically, yuck. The roof scoop was ok on a GT1, because it was mid-engined and long and the scoop was fairly small. On the silver car show above it looks like a mullet.

[widebody911]

Originally posted by jyl
Stylistically, yuck. The roof scoop was ok on a GT1, because it was mid-engined and long and the scoop was fairly small. On the silver car show above it looks like a mullet.

More like a mowhawk....

[widebody911]

Here's pix of the mold. I think I'll lay one up just to see what it looks like.

[Chuck Moreland]

Aesthetically, I'm not a big fan. But I imagine it would work well to feed cool air. Perhaps even ram-air to the intake.

Aero drag would suffer, as would rearward visibility. And I suspect lift at the rear increases as the curve down to the engine lid is even more severe than than stock.

How about creating a similar airbox that fits under the roofline, inside the cabin, with an intake cut into the top of the windshield.

[Grady Clay]

I had always heard that the high pressure area was at the base of the windshield and on the cowl. I saw a full windshield 914-6 racer with an intake duct running through the passenger compartment from the cowl.

Best,
Grady

[Shuie]

How about piping vents from already available GT Racing plexi quarter windows through the rear firewall directly into the intake? The TWM airboxes look like they could work well for this if you mounted them so the inlets pointed towards the firewall

here are the airboxes. I cant get a good pic of the GT Racing windows I talking about, but they are the NASCAR looking ones, not the R units.

[widebody911]

Chuck's and Sherman's ideas make the most sense from an aerodynamic standpoint, and they each have their merits. The mold I have is the result of someone else having this idea at one time and executing it. I don't know that guy, so I can't ask him directly how well it worked. Since I have access to the mold, I figured it might be worth a shot.

Another idea I had was to use the scoop simply to get air into to cabin, for driver comfort. Put a couple small holes in it with directional vents... Just an idea. With a fiberglass roof, you have a lot of options

[island911]

Originally posted by widebody911
.. ..
My question is, does it seem like this would be a valid way to enhance cooling?
.

Not really the best for a 911.

That would pickup some dynamic pressure only. If you were to place an intake . . .say, where the fresh air vent is located, you would get dynamic pressure PLUS static pressure, built-up from the surrounding area (all hte air "stacking-up" against the windshield)

911s have some fairly poorly raked windshields. SO, maybe if you pointed the opening down, over the top edge of the windshield, like a big old nose . . ..


not to mention that would look like crap on a cabrio.

[island911]

oops . ..I just read this. Grady has the right idea.

Originally posted by Grady Clay
I had always heard that the high pressure area was at the base of the windshield and on the cowl. I saw a full windshield 914-6 racer with an intake duct running through the passenger compartment from the cowl.

Best,
Grady

[Shuie]

Out of curiosity, would there be any benefit add to going through airscoops on the quarter windows into something like the TWM airboxes? How much of an air pressure difference is seen there. Would the engine be choking for air when the car was standing still?

[Jack Olsen]

Putting a cap on top of the airbox seems like a bad idea, to me. Aside from track-only cars, a 911 spends a lot of time not going very fast. Under those conditions, you're forcing the cooling system to suck air through a kind of peculiarly-shaped straw. Then, at speed, where it's doing you some good, you're also adding drag. What's more, it's only adding air to the intake (and in some models, the engine-mounted cooler), which isn't a place where 911's are normally starved for lots of rich, cool air (thanks to that big fan).

Again, outside of track cars, temperature problems tend to be more acute in stop-and-go traffic, where this kind of thing would hurt rather than help.

Naca ducts on the quarter windows of your cab tops would make more sense, IMO. But I wouldn't block off the engine lid.

[ted]

Loren from 911 Design used a roof scoop for the intercooler on his 750hp twin turbo.
Rear visablility is reduced.



911 design wing envy...