[DeTomaso] New engine now air scoops

[Julian Kift]

Mike wrote; "Air will *have* to flow inward because the engine will be creating vacuum and the airbox will be sealed so air can't come from anyplace else."
 
Not if there is enough of a reduced pressure zone on the exterior of the air scoops (are they in the boundary layer?) where you'll just starve the engine of air and run rich. That could also be very dependent on vehicle speed and air flow around the vehicle, possibly also resulting in a shift in fuel/air ratio with speed. The F/A portion is fairly easily solved if you have EFI, but still doesn't ensure adequate overall air flow.
 
Have the folks that have done the aerodynamics testing established that the air flow out of the removed windows is a) due to a high pressure zone within the engine compartment causing outflow or b) a reduced pressure zone on the exterior creating vacuum flow?
 
Julian
 
Date: Mon, 8 Dec 2014 17:56:06 -0500
To: guson at home.se
CC: detomaso at poca.com
Subject: Re: [DeTomaso] New engine now air scoops
From: detomaso at poca.com 
In a message dated 12/8/14 13 45 4, guson at home.se writes:
 
 
> There's a lot of body metal between the stock fake gills and the engine 
> compartment. 
> 
>>>True.   But there is NO metal between the rear quarter window glass and 
the engine compartment. :>)
 
> >Not to mention that the right side gill houses the fuel filler on most 
> cars.
> 
>>>True, but irrelevant.   The Amerisport grills are solid in the area of 
the stock body 'gill'/fuel filler on the left side, and body 'gill' on the 
right side.   They are open in the area of the quarter windows (in front of 
these two areas).   When the glass and stock 'gills' are removed and they are 
installed in their place, they merely serve as vents.   If there is no 
plumbing associated with this modification, it's almost assured that air will 
flow out from the engine bay through these vents.
 
Some, like John Taphorn (as seen in the most recent Profiles) have carved 
out metal ducts which will (someday) be attached to hoses connecting them to 
a sealed airbox, and take the place of the glass windows; once they are 
hooked up to the work-in-progress airbox, air will then be taken in through the 
Amerisport grills.   Air will *have* to flow inward because the engine will 
be creating vacuum and the airbox will be sealed so air can't come from 
anyplace else.
 
See the attached photo of his passenger side ductwork (grill removed to 
show it clearly).
 
Mike
 

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-------------- next part --------------
   Mike wrote; "Air will *have* to flow inward because the engine will be
   creating vacuum and the airbox will be sealed so air can't come from
   anyplace else."

   Not if there is enough of a reduced pressure zone on the exterior of
   the air scoops (are they in the boundary layer?) where you'll just
   starve the engine of air and run rich. That could also be very
   dependent on vehicle speed and air flow around the vehicle, possibly
   also resulting in a shift in fuel/air ratio with speed. The F/A portion
   is fairly easily solved if you have EFI, but still doesn't ensure
   adequate overall air flow.

   Have the folks that have done the aerodynamics testing established that
   the air flow out of the removed windows is a) due to a high pressure
   zone within the engine compartment causing outflow or b) a reduced
   pressure zone on the exterior creating vacuum flow?

   Julian

   Date: Mon, 8 Dec 2014 17:56:06 -0500
   To: guson at home.se
   CC: detomaso at poca.com
   Subject: Re: [DeTomaso] New engine now air scoops
   From: [1]detomaso at poca.com
   In a message dated 12/8/14 13 45 4, guson at home.se writes:
   > There's a lot of body metal between the stock fake gills and the
   engine
   > compartment.
   >
   >>>True. But there is NO metal between the rear quarter window glass
   and
   the engine compartment. :>)
   > >Not to mention that the right side gill houses the fuel filler on
   most
   > cars.
   >
   >>>True, but irrelevant. The Amerisport grills are solid in the area of
   the stock body 'gill'/fuel filler on the left side, and body 'gill' on
   the
   right side. They are open in the area of the quarter windows (in front
   of
   these two areas). When the glass and stock 'gills' are removed and they
   are
   installed in their place, they merely serve as vents. If there is no
   plumbing associated with this modification, it's almost assured that
   air will
   flow out from the engine bay through these vents.
   Some, like John Taphorn (as seen in the most recent Profiles) have
   carved
   out metal ducts which will (someday) be attached to hoses connecting
   them to
   a sealed airbox, and take the place of the glass windows; once they are
   hooked up to the work-in-progress airbox, air will then be taken in
   through the
   Amerisport grills. Air will *have* to flow inward because the engine
   will
   be creating vacuum and the airbox will be sealed so air can't come from
   anyplace else.
   See the attached photo of his passenger side ductwork (grill removed to
   show it clearly).
   Mike

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References

   1. mailto:detomaso at poca.com