[DeTomaso] Fw: Elephant ears

Sat Jun 20 19:52:58 EDT 2009

I have a holley 650 which has a four inch intake opening. I am using a dual
plenum that has two 4 inch openings . The two 4 inch openings are connected
to two completly enclosed K&N style cone shaped air filters. The feed end of
the two air cleaners are feed by two 3" ducts that lead to the back of the
car and pick up air through two naca ducts that are placed to pick up air as
it  passes under the rear of the car. The naca ducts are not parralell to
the road surface put are tilted slightly so that the front of the ducts (
the narrow part of the opening is slightly closer to the  ground ) I wasn't
able to place the naca ducts in a position that would provide a smooth
surface to allow the ducts to work the way they are supposed to. I didn't
want them to "scoop" the air which I felt would create drag and possibly
create a "ram air " effect which I am trying to avoid . I used the two ducts
instead of one because I know that the longer the ducting the more
restrictive the flow. I felt that doubling the ducting diameter would
provide sufficent air flow. I had to reduce the ducting from 4" diameter  to
3" diameter due to the availability of matreials.The corrogated ducting
allowed me the lattitude to experiment with differnt placement locations.
the position of the naca ducts is not permenant and they are held in place
temporarily by nylon ties. I have an infra red non-contact laser themometer
to identify air temp differences and an annenometer that is the ducted fan
type that is also 4 "diameter. It measueres airflow in several  diiffernt
scale including cfm and also has records temperature. Although I did not use
advanced mathematics to design the system I do plan on using my annenometer
to measure the results and the actual air flow volum and air temp. Once I
have determined the omptimal position for the naca ducts to pick up the cool
air source. I remember when I worked for Toyota and the first came out with
the MR2  they had new induction system that used two ducts of unequal
lenghts  to feed the fuel injection air intake. the principle was similar
tothe way air travels across a wing . Air passes across a wing that has
unequal distances (the top surface distance vs the bottom surface
difference.Since the air enters the wing surface at a constant speed but has
to travel a greater distance over the top of the wing vs the bottom of the
wing when the air flow exits at the back of the wing the air on the top side
is traveling at a greater speed( they enter point A. the front of the wing
at the same time and exit at point B the back of the wing at the same time.
Sine air flow on top has to travel a greater distance it has to travel at a
higher rate of speed. The air exiting is at the back of the wing is very
turbulent as the two flows join back together traveling at different speeds.
The resulting joining of the two flows creates vortices of high turbulance.
The way this is related to the air intake of the fuel injection system is
this by having the air intake travel down two different paths of un equal
distances When they rejoin at the combustion chamber the vortieces create at
more thorough air fuel mixture which improved total combustion.. So I was
operating under the beleif that a turbulent air fuel flow at the entrance to
the combustion chamber was a good thing. Once I have determined the final
postion of the naca ducts I can switch to smooth cylindrical tubing that is
4" in diameter so two ducts of 4" diameter will provide twice the diameter
of the intake at it's narrowest point ( weak link theory) so I should have
more then enough air flow to provide for the maximum air flow  my 351
cleveland engine and Holley 650 could possiably use. Although I don't have
the education to do the math calculations to determine the maximum air flow
demands I beleive I have enough of a fundemental understanding of the
dynamics and with the tools i have ( anomometer and infra red thermometer)
as well as measureing  apparent performance improvements or reductions of
performance i believe I will ultimately end up with an impprovement over the
stock set up. I would welcome any input from  Göran or anyone else that has
mathematics or engineering background ( or just has an interest in the
subject matter) The important thing to me is that I believe there are
improvements to be had and the satisfaction of the experimental process (If
the end result is an improvement). My ability to test my modifications so
far has been put ob hold by my broken leg.
Boyd

On Thu, Jun 18, 2009 at 3:21 PM, Göran Malmberg <hemipanter at hemipanter.se>wrote:

> The samed goes for water hose that looks like an accordion!
> Goran
>
> -----Ursprungligt meddelande-----
> Från: detomaso-bounces at realbig.com [mailto:detomaso-bounvvces at realbig.com<detomaso-bounces at realbig.com>
> ]
> För JDeRyke at aol.com
> Skickat: den 18 juni 2009 20:39
> Till: wdemelo at cogeco.ca; detomaso at realbig.com
> Ämne: Re: [DeTomaso] Fw:  Elephant ears
>
> An article in a recent Circle Track magazine by an aerospace engineer
> said
> that corrugated flex tubing is very bad at transferring air in any
> quantities, due to the corrugations causing massive turbulence inside,
> reducing flow.
> So a 3" or 4" dia corrugated duct (for instance) will transfer far less
> air
> than one might think, whether you're talking about engine air or brake
> cooling. And while this is one of those 'jeeeez, of course' things, it
> never
> really occurred to me and I tend to pay attention to such details. So
> with no
> data and Holley carbs having a 5-1/4" entry flange, maybe a 6" duct?
> FWIW,
> y'all- J Deryke
>
>
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