[DeTomaso] Has anyone researched hood vent designs?

Tue Aug 2 10:55:07 EDT 2016

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.

_______________________________________________

Detomaso Email List is not managed by POCA
Posted emails must not exceed 1.5 Megabytes
DeTomaso mailing list
DeTomaso at server.detomasolist.com
http://server.detomasolist.com/mailman/listinfo/detomaso
DeTomaso Info Page<http://server.detomasolist.com/mailman/listinfo/detomaso>
server.detomasolist.com
This is the DeTomaso mailing list, a free and open forum for the discussion of issues surrounding all DeTomaso automobiles. This is an unmoderated mailing list ...

DeTomaso Info Page<http://server.detomasolist.com/mailman/listinfo/detomaso>
server.detomasolist.com
This is the DeTomaso mailing list, a free and open forum for the discussion of issues surrounding all DeTomaso automobiles. This is an unmoderated mailing list ...

DeTomaso Info Page<http://server.detomasolist.com/mailman/listinfo/detomaso>

server.detomasolist.com
This is the DeTomaso mailing list, a free and open forum for the discussion of issues surrounding all DeTomaso automobiles. This is an unmoderated mailing list ...

To manage your subscription (change email address, unsubscribe, etc.) use the links above.

Members who post to this list grant license to the list to forward any message posted here to all past, current, or future members of the list. They also grant the list owner permission to maintain an archive or approve the archiving of list messages.

-------------- next part --------------
   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.
   _______________________________________________
   Detomaso Email List is not managed by POCA
   Posted emails must not exceed 1.5 Megabytes
   DeTomaso mailing list
   DeTomaso at server.detomasolist.com
   [1]http://server.detomasolist.com/mailman/listinfo/detomaso
   [2]DeTomaso Info Page
   server.detomasolist.com
   This is the DeTomaso mailing list, a free and open forum for the
   discussion of issues surrounding all DeTomaso automobiles. This is an
   unmoderated mailing list ...
   [3]DeTomaso Info Page
   server.detomasolist.com
   This is the DeTomaso mailing list, a free and open forum for the
   discussion of issues surrounding all DeTomaso automobiles. This is an
   unmoderated mailing list ...
   DeTomaso Info
   Page<[4]http://server.detomasolist.com/mailman/listinfo/detomaso>
   server.detomasolist.com
   This is the DeTomaso mailing list, a free and open forum for the
   discussion of issues surrounding all DeTomaso automobiles. This is an
   unmoderated mailing list ...
   To manage your subscription (change email address, unsubscribe, etc.)
   use the links above.
   Members who post to this list grant license to the list to forward any
   message posted here to all past, current, or future members of the
   list. They also grant the list owner permission to maintain an archive
   or approve the archiving of list messages.

References

   1. http://server.detomasolist.com/mailman/listinfo/detomaso
   2. http://server.detomasolist.com/mailman/listinfo/detomaso
   3. http://server.detomasolist.com/mailman/listinfo/detomaso
   4. http://server.detomasolist.com/mailman/listinfo/detomaso