[DeTomaso] Has anyone researched hood vent designs?

[Larry Stock]

Understood Chuck, and at about 180 MPH the rear of the Pantera will lift
off due this effect but not the front because of the downward pressure
from the frontal hood area. An aluminum front hood will actually collapse
inward at about the same speed.
Larry

On 8/2/16, 7:26 PM, "DeTomaso on behalf of Chuck and Linda Huber"
<detomaso-bounces at server.detomasolist.com on behalf of lindahuber at cox.net>
wrote:

>I might respectfully disagree (obviously not having tested this on my
>own...)
>
>The airflow over the car (like that over a wing) will be accelerated.  The
>air going over the top of the car will create lift (as in the front of the
>stock Pantera lifting up at speeds above 125 mph, such that handling gets
>squirrely).  This lift is due to low pressure over the top of the car
>(again
>like an airplane wing), which will tend to pull air out through the hood
>vents.
>
>I agree that ducting like GT-40s, Goran's picture, and Comp2 will be much
>more efficient at exhausting air than the hibacci grates that most use.
>
>I do agree this effect would be more pronounced with a flat bottom.
>
>
>Chuck 
>
>-----Original Message-----
>From: Julian Kift [mailto:julian_kift at hotmail.com]
>Sent: Tuesday, August 2, 2016 7:55 AM
>To: James coyne; Rod Kunishige; scottcouchman at yahoo.com;
>detomaso at server.detomasolist.com; Ken Green
>Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>Okay, let's put our engineering hats on and have some fun technical
>discussion..... it sure beats the discussion over POCA of late!
>
>
>I think (but readily admit my engineering degree is not in aerodynamics!)
>hood vents and location play a minor part in overall aerodynamics.
>
>
>Hood vents are a great way to provide additional cooling in traffic, but
>perhaps  limited value at high speed when the front of the hood becomes a
>high pressure area. Now you have opposing forces at play and at speed 'x'
>the pressure is likely enough to overcome that produced by the radiator
>fans
>(I imagine that 'x' would not be excessively high, perhaps even highway
>cruising speed). So outside air now reverse enters the hood vents or at a
>minimum restricts fan flow resulting in air that is forced under the car
>i.e. back to the original Ford design concept. A Gurney lip on the frontal
>edge of hood vents would help create a low pressure area, but I still
>believe the air from the radiators will ultimately be forced under the car
>at some speed now x+y.
>
>
>As testament to the pressures on the hood Larry Stock told me that Mike
>Cooke collapsed an aluminum hood at high speed.
>
>
>As alternative thinking, most cars that employ an aerodynamic frontal hood
>vent do so in combination with a full flat underside. I think this is a
>critical element in the success of the design and one without the other is
>likely non productive. Furthermore most running Pantera's in ORR have
>reported that a front air dam is a key element in preventing front end
>lift
>at +150mph, again attesting to restricting air flow under the car is the
>most critical element.  I'd go for the front air  dam in combination with
>a
>fully enclosed flat floor/tray as my first modifications and leave cutting
>the front trunk aspect (and the ensuing frontal rigidity impact).
>
>
>As an a side the popular radiator fan shrouds also become restrictive at
>high speed and require opening up, some have achieved this with simple
>hinged flaps that can freely open as the pressure through the radiator
>increases.
>
>
>Julian
>
>________________________________
>From: Ken Green <kenn_green at yahoo.com>
>Sent: Monday, August 1, 2016 10:28 AM
>To: James coyne; Julian Kift; Rod Kunishige; scottcouchman at yahoo.com;
>detomaso at server.detomasolist.com
>Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>Probably more correct to say I intend the car to be able to run well over
>150.  Not sure if I want to drive that fast on a country road.  I would
>be a
>lot more comfortable having fun at lower speeds in an ORR, and trying the
>flying mile type events to see how fast the car can actually go.
>
>The older we get, the longer it takes to heal.
>
>Ken
>
>
>________________________________
>From: James coyne <tecnosound at hotmail.com>
>To: Julian Kift <julian_kift at hotmail.com>; Rod Kunishige
><rkunishige at hotmail.com>; "scottcouchman at yahoo.com"
><scottcouchman at yahoo.com>; Ken Green <kenn_green at yahoo.com>;
>"detomaso at server.detomasolist.com" <detomaso at server.detomasolist.com>
>Sent: Monday, August 1, 2016 9:00 AM
>Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>I believe it is indeed Ken's intension to run in the 150mph+ classes at
>open
>road events .
>
>
>________________________________
>From: DeTomaso <detomaso-bounces at server.detomasolist.com> on behalf of
>Julian Kift <julian_kift at hotmail.com>
>Sent: Monday, August 1, 2016 7:49 AM
>To: Rod Kunishige; scottcouchman at yahoo.com; Ken Green;
>detomaso at server.detomasolist.com
>Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>This seems like an awful lot of work for little to no gain, is this a
>dedicated race car that will be running the 150mph+ classes at an Open
>Road
>Race?
>
>
>Julian
>
>________________________________
>From: DeTomaso <detomaso-bounces at server.detomasolist.com> on behalf of Ken
>Green via DeTomaso <detomaso at server.detomasolist.com>
>Sent: Monday, August 1, 2016 7:00 AM
>To: Rod Kunishige; scottcouchman at yahoo.com
>Cc: detomaso at server.detomasolist.com
>Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>My gut feeing is the opening needs to be moved back to reduce air pressure
>over the opening.  And that probably depends on speed.
>Ken
>
>      From: Rod Kunishige <rkunishige at hotmail.com>
> To: "scottcouchman at yahoo.com" <scottcouchman at yahoo.com>; Ken Green
><kenn_green at yahoo.com>
>Cc: "detomaso at server.detomasolist.com" <detomaso at server.detomasolist.com>
> Sent: Sunday, July 31, 2016 10:13 PM
> Subject: Re: [DeTomaso] Has anyone researched hood vent designs?
>
>  I really like the idea of boxing the trunk in your design.
>
>  It means moving the support ribs for the hood.
>
>  Can you enlarge the opening by starting closer to the radiator?
>  From: Ken Green <kenn_green at yahoo.com>
>  I think photos of that car were posted a year ago?  I want the car to
>  look like a Pantera, not a GT40.
>  en
>  From: "scottcouchman at yahoo.com" <scottcouchman at yahoo.com>
>  You should talk with Tony Ortiz in Arizona. He modified his Pantera to
>  install front and rear GT40 clips.
>
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