[DeTomaso] Air to engine discussion
jgkrenton at comcast.net
jgkrenton at comcast.net
Tue Dec 9 13:14:19 EST 2014
All:
Sort of related....
A couple of weeks ago I was trying to test a "4 inch venturi" for an old airplane. (These devices are supposed to generate 4 inches of vacuum at speeds greater than 60 MPH for instrumentation systems in the airplane.) I figured I'd clamp it to the passengers window on my truck. (true, not a Pantera, but I only needed 60 MPH.) The venturi mounted about 4 inches off the passengers side window.
The first test showed absolutely no vacuum.
I finally figured out I needed to hold the venturi almost 18 inches off the side of the truck to get clean enough air for the venturi to work properly. (4 inches vacuum at 60 MPH)
While this isn't a pitot tube or a Pantera it is somewhat illustrative of the air disturbance around a vehicle in motion.
For what it's worth, a pitot tube is relatively simple to make. If you look at vintage airplanes their pitot systems are very simple, often just a pair of 1/8 inch ID tubes (aka something like a steel brake line) sticking out into what should be clear air. One tube with an open end for the "ram effect" and the other tube with a closed end an holes drilled in the sides for the "static" or "reference" air. This would be pretty simple to cobble up so you could set it at various distances from the side vent area of a Pantera to check the depth of the boundary layer. (look for different pressures as the distance changes given a fixed ground speed.)
Good luck.
Jeff/2467
----- Original Message -----
From: "Ken Green via DeTomaso" <detomaso at poca.com>
To: "John Taphorn" <jtaphorn at kingwoodcable.com>, "Will Kooiman" <will.kooiman at gmail.com>, "Mendez, Ed" <edducati at mac.com>, "Matt Wells" <nwpantera at gmail.com>, "Tomas Gunnarsson" <guson at home.se>, "Boyd Casey" <boyd411 at gmail.com>, "Asa Jay Laughton" <asajay at asajay.com>
Cc: detomaso at poca.com
Sent: Tuesday, December 9, 2014 9:35:02 AM
Subject: Re: [DeTomaso] Air to engine discussion
I looked at some boundary layer articles last night, one article used a pitot tube array to measure air velocity and showed the boundary layer not very thick at high speed and the air velocity increases quickly in the boundary layer, so you really don't need to escape the entire layer to benefit:
http://www.consultkeithyoung.com/content/calculating-boundary-layer-thickness-choose-pitot-tube-height-f1-car-using-theory-and-pitot
Has anyone tried using a pitot tube to measure the relative air velocity?
Ken
From: John Taphorn <jtaphorn at kingwoodcable.com>
To: Will Kooiman <will.kooiman at gmail.com>; Ed Mendez <edducati at mac.com>; Matt Wells <nwpantera at gmail.com>
Cc: "detomaso at poca.com" <detomaso at poca.com>
Sent: Tuesday, December 9, 2014 5:36 AM
Subject: Re: [DeTomaso] Air to engine discussion
Does the video dispel the notion that there is poor airflow along the
side of the car? It appears so to me.
If so, that seems pretty noteworthy as many on this forum have
vigorously advocated that air flow along the panels was poor for quite a
while.
Another Pantera myth??
JT
On 12/9/2014 5:03 AM, Will Kooiman wrote:
> I like that video. I remember watching it a while back.
>
> I¹m surprised by the yarn going up. I noticed that it was straight back
> by the fake vents, though.
>
> On 12/9/14, 1:05 AM, "Ed Mendez" <edducati at mac.com> wrote:
>
>> That is cool Matt,
>>
>> I shared it on the POCA Facebook page.
>>
>> Thanks,
>>
>> Ed
>>
>>
>>> On Dec 8, 2014, at 19:52, Matt Wells <nwpantera at gmail.com> wrote:
>>>
>>> A while back I messed around with some yarn and my gopro just to see.
>>> I don't know if this helps figure anything out short of just trying
>>> it.
>>> There were some tendencies I saw with the tufts going upwards
>>> slightlyA
>>> but no vacuum really noticed. This video is shot between 0-120mph.
>>> It was a liitle boring so I added tunes and wrote some corny stuff
>>> which makes little sense now.
>>> Might be enlightening and/or entertaining for some.
>>> Matt
>>> 3584
>>> [1]https://www.youtube.com/watch?v=3AaYJ3pkvR0
>>> ----- Original Message -----
>>> From: "David" <[2]adin at frontier.net>
>>> To: <[3]detomaso at poca.com>
>>> Sent: Sunday, December 07, 2014 8:11 PM
>>> Subject: [DeTomaso] New engine.
>>>> Two comments here about getting air to the engine:>
>>>> I have documented a 50 degree difference in air temps between the
>>> airfilter
>>>> area and the window area.A Something needs to be done.>
>>>> My tuft tests (admittedly at legal speeds)A did NOT show a boundary
>>> layer at
>>>> the quarter window.A Do things change at speed?A (stay tuned!)>
>>>>
>>>> David
>>> References
>>>
>>> 1. https://www.youtube.com/watch?v=3AaYJ3pkvR0
>>> 2. mailto:adin at frontier.net
>>> 3. mailto:detomaso at poca.com
>>> _______________________________________________
>>>
>>> Detomaso Forum Managed by POCA
>>>
>>> DeTomaso mailing list
>>> DeTomaso at poca.com
>>> http://poca.com/mailman/listinfo/detomaso_poca.com
>>
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> DeTomaso mailing list
>> DeTomaso at poca.com
>> http://poca.com/mailman/listinfo/detomaso_poca.com
>
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso_poca.com
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-------------- next part --------------
All:
Sort of related....
A couple of weeks ago I was trying to test a "4 inch venturi" for an
old airplane. (These devices are supposed to generate 4 inches of
vacuum at speeds greater than 60 MPH for instrumentation systems in the
airplane.) I figured I'd clamp it to the passengers window on my
truck. (true, not a Pantera, but I only needed 60 MPH.) The venturi
mounted about 4 inches off the passengers side window.
The first test showed absolutely no vacuum.
I finally figured out I needed to hold the venturi almost 18 inches off
the side of the truck to get clean enough air for the venturi to work
properly. (4 inches vacuum at 60 MPH)
While this isn't a pitot tube or a Pantera it is somewhat illustrative
of the air disturbance around a vehicle in motion.
For what it's worth, a pitot tube is relatively simple to make. If you
look at vintage airplanes their pitot systems are very simple, often
just a pair of 1/8 inch ID tubes (aka something like a steel brake
line) sticking out into what should be clear air. One tube with an
open end for the "ram effect" and the other tube with a closed end an
holes drilled in the sides for the "static" or "reference" air. This
would be pretty simple to cobble up so you could set it at various
distances from the side vent area of a Pantera to check the depth of
the boundary layer. (look for different pressures as the distance
changes given a fixed ground speed.)
Good luck.
Jeff/2467
__________________________________________________________________
From: "Ken Green via DeTomaso" <detomaso at poca.com>
To: "John Taphorn" <jtaphorn at kingwoodcable.com>, "Will Kooiman"
<will.kooiman at gmail.com>, "Mendez, Ed" <edducati at mac.com>, "Matt Wells"
<nwpantera at gmail.com>, "Tomas Gunnarsson" <guson at home.se>, "Boyd Casey"
<boyd411 at gmail.com>, "Asa Jay Laughton" <asajay at asajay.com>
Cc: detomaso at poca.com
Sent: Tuesday, December 9, 2014 9:35:02 AM
Subject: Re: [DeTomaso] Air to engine discussion
I looked at some boundary layer articles last night, one article used a
pitot tube array to measure air velocity and showed the boundary
layer not very thick at high speed and the air velocity increases
quickly in the boundary layer, so you really don't need to escape the
entire layer to benefit:
http://www.consultkeithyoung.com/content/calculating-boundary-layer-thi
ckness-choose-pitot-tube-height-f1-car-using-theory-and-pitot
Has anyone tried using a pitot tube to measure the relative
air velocity?
Ken
From: John Taphorn <jtaphorn at kingwoodcable.com>
To: Will Kooiman <will.kooiman at gmail.com>; Ed Mendez
<edducati at mac.com>; Matt Wells <nwpantera at gmail.com>
Cc: "detomaso at poca.com" <detomaso at poca.com>
Sent: Tuesday, December 9, 2014 5:36 AM
Subject: Re: [DeTomaso] Air to engine discussion
Does the video dispel the notion that there is poor airflow along the
side of the car? It appears so to me.
If so, that seems pretty noteworthy as many on this forum have
vigorously advocated that air flow along the panels was poor for quite
a
while.
Another Pantera myth??
JT
On 12/9/2014 5:03 AM, Will Kooiman wrote:
> I like that video. I remember watching it a while back.
>
> IA^1m surprised by the yarn going up. I noticed that it was straight
back
> by the fake vents, though.
>
> On 12/9/14, 1:05 AM, "Ed Mendez" <edducati at mac.com> wrote:
>
>> That is cool Matt,
>>
>> I shared it on the POCA Facebook page.
>>
>> Thanks,
>>
>> Ed
>>
>>
>>> On Dec 8, 2014, at 19:52, Matt Wells <nwpantera at gmail.com> wrote:
>>>
>>> A while back I messed around with some yarn and my gopro just to
see.
>>> I don't know if this helps figure anything out short of just
trying
>>> it.
>>> There were some tendencies I saw with the tufts going upwards
>>> slightlyA
>>> but no vacuum really noticed. This video is shot between
0-120mph.
>>> It was a liitle boring so I added tunes and wrote some corny
stuff
>>> which makes little sense now.
>>> Might be enlightening and/or entertaining for some.
>>> Matt
>>> 3584
>>> [1]https://www.youtube.com/watch?v=3AaYJ3pkvR0
>>> ----- Original Message -----
>>> From: "David" <[2]adin at frontier.net>
>>> To: <[3]detomaso at poca.com>
>>> Sent: Sunday, December 07, 2014 8:11 PM
>>> Subject: [DeTomaso] New engine.
>>>> Two comments here about getting air to the engine:>
>>>> I have documented a 50 degree difference in air temps between the
>>> airfilter
>>>> area and the window area.A Something needs to be done.>
>>>> My tuft tests (admittedly at legal speeds)A did NOT show a
boundary
>>> layer at
>>>> the quarter window.A Do things change at speed?A (stay tuned!)>
>>>>
>>>> David
>>> References
>>>
>>> 1. https://www.youtube.com/watch?v=3AaYJ3pkvR0
>>> 2. mailto:adin at frontier.net
>>> 3. mailto:detomaso at poca.com
>>> _______________________________________________
>>>
>>> Detomaso Forum Managed by POCA
>>>
>>> DeTomaso mailing list
>>> DeTomaso at poca.com
>>> http://poca.com/mailman/listinfo/detomaso_poca.com
>>
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> DeTomaso mailing list
>> DeTomaso at poca.com
>> http://poca.com/mailman/listinfo/detomaso_poca.com
>
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso_poca.com
>
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DeTomaso mailing list
DeTomaso at poca.com
http://poca.com/mailman/listinfo/detomaso_poca.com
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