[DeTomaso] High Ported Iron Closed Chamber 4V head flow results
Daniel C Jones
daniel.c.jones2 at gmail.com
Sun Feb 9 22:01:45 EST 2014
> Not sure why the Jet engine was used as an example, those S shaped port directors in those engines are designed to slow the air down by several hundred miles per hour before it enters the jet engine. SST and SR71 did too
The 727 is subsonic so no need to reduce the flow by several hundred
MPH. There are vortex generators, turning vanes and stators, none of
which are used to slow air down. The pupose of vortex generators is to
energize the boundary layer (intentionally trip the laminar boundary
layer to turbulent) because turbulent boundary layers are less likely
to separate. Turning vanes are used to direct flow and stators are
designed to cancel the swirling effect of rotating elements like
compressors. On supersonic aircraft, inlets are designed to reduce
flow to subsonic speeds before it flows through the compressor. This
can be done with active geometry (opening up throat area) or by using
a shock wave. The SR-71 used variable inlet geometry and also
directed most of the flow at high speeds around the compressors to the
outside of the engine into ramjet like sections of the engine.
> Why would you want to slow down your fuel air mix? Performance items like Blowers and Superchargers are used to increase the speed and pressure to attain greater performance.
For a normally aspirated engine, there are flow losses that occur as
you get transonic speeds. As speed is increased to 0.6 Mach or so,
the energy required to increase the flow speed is more than the power
increase associated with the increased velocity. The limiting case is
the choked flow that occurs as throat velocity is increased to Mach 1.
In cases like that, increasing the minimum cross-sectional area to
slow the flow will result in increased power. With a supercharger,
you can get an increase in mass flow rate due by compression.
Dan Jones
On Sun, Feb 9, 2014 at 5:57 PM, michael at michaelshortt.com
<michael at michaelshortt.com> wrote:
> Not sure why the Jet engine was used as an example, those S shaped port
> directors in those engines are designed to slow the air down by several
> hundred miles per hour before it enters the jet engine.
> SST and SR71 did too.
> Why would you want to slow down your fuel air mix? Performance items like
> Blowers and Superchargers are used to increase the speed and pressure to
> attain greater performance.
>
> I don't get why that was an example.
>
> Michael
>
> On Feb 9, 2014 6:47 PM, "Sean Korb" <spkorb at gmail.com> wrote:
>>
>> I'm not sure if this is germane but I am utterly fascinated.
>>
>> http://speedtalk.com/forum/viewtopic.php?t=4785
>>
>>
>> On Sun, Feb 9, 2014 at 5:55 PM, Charles Engles <cengles at cox.net> wrote:
>> > Dear Dan,
>> >
>> >
>> > You wrote: "....and shear vanes screwed into the intake
>> > port
>> > floors."
>> >
>> > For the amateur engine builder, what are shear vanes?
>> >
>> > Very curious, Chuck Engles
>> >
>> > -----Original Message-----
>> > From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of Daniel C
>> > Jones
>> > Sent: Sunday, February 09, 2014 4:24 PM
>> > To: POCA list
>> > Subject: [DeTomaso] High Ported Iron Closed Chamber 4V head flow results
>> >
>> > A while back, Dave McLain flowed a set of old iron closed chamber 4V
>> > heads
>> > with the 1970's Pro Stock style high port exhaust plate and shear vanes
>> > screwed into the intake port floors. I thought I'd share the results.
>> > Flowed on a Super Flow bench. Tested at 10" and converted to 28".
>> > 2.19"
>> > intake valve and 1.71" exhaust. Completely stock combustion chambers.
>> >
>> > Lift Intake Exhaust
>> >
>> > Inch CFM CFM
>> >
>> > 0.025 15.9 10.2
>> >
>> > 0.050 33.2 28.5
>> >
>> > 0.100 65.6 60.0
>> >
>> > 0.150 100.6 89.0
>> >
>> > 0.200 137.8 109.8
>> >
>> > 0.250 167.6 124.1
>> >
>> > 0.300 195.8 141.4
>> >
>> > 0.350 224.0 155.4
>> >
>> > 0.400 245.6 166.8
>> >
>> > 0.450 261.4 176.7
>> >
>> > 0.500 278.8 185.3
>> >
>> > 0.550 289.7 194.7
>> >
>> > 0.600 300.9 204.2
>> >
>> > 0.650 312.1 215.2
>> >
>> > 0.700 322.0 225.8
>> >
>> > 0.750 325.7 234.4
>> >
>> > 0.800 307.8 239.7
>> >
>> > Not too bad for 1970's small block cylinder heads.
>> >
>> > Dan Jones
>> >
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>>
>>
>> --
>> Sean Korb spkorb at spkorb.org http://www.spkorb.org
>> '65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
>> "The more you drive, the less intelligent you get" --Miller
>> "Computers are useless. They can only give you answers." -P. Picasso
>>
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