Twin Centrifugals VS Single

Walter Sherwin wsherwin at home.com
Fri Apr 13 02:25:24 GMT 2001


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Forwarded from another list.....



>Here's something I've been tossing around in my mind, for street toy =
use, and I'd love to hear more from the group........

>Let's say you have a large displacement stroker motor, and you desire =
to artificially stuff it's hunger with centrifugal supercharging (non =
manufacturer specific at this >point).  The typical approach today would =
be to seek out a largish single centrifugal unit that would do the dirty =
job, and pulley it to gain the max desired air flow/boost at >a specific =
engine speed.  This would net you a large diameter centrifugal, =
operating at a somewhat less than maximum impeller speed, hung from one =
side of your >engine.  This would work, and you would prolly have a cog =
belt drive arrangement as a result, if you wanted serious manifold =
pressure.  Of course this will generate a new >force/belt vector load at =
the nose of the crank, that may or may not affect your front bearings.  =
One might even direct the output of this large compressor to a single =
>inter/aftercooler device for post cooling.

>Let's consider a different approach......

>What about mounting two smaller centrifugals, low on the motor, perhaps =
directly opposed to the crank centerline so as to cancel the belt load =
vectors.  Further imagine >the discharge(s) from these compressors being =
directed thru two parallel inter/aftercooler exchangers (ala: Porsche =
twin turbo setups).  The twin intercoolers might be a >bit easier to =
position within a street vehicle.  At an esoteric design level, twins =
could allow a person to fabricate an engine bay setup that has a =
symmetric and artful >appearance.

>Cost aside, does anyone see any further advantages/disadvantages to =
running two slightly smaller compressors in place of one larger unit?  =
Obviously, the cost will be >higher with twins.  I'm more wondering =
about airflow versus crank speed, throttle response, boost response =
profile, parasitic drain at a given combined flow/pressure, >etc.   =20

>Thoughts would be appreciated;
>Walt.




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<DIV><FONT size=3D2>Forwarded from another list.....</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2></FONT><BR></DIV>
<DIV><FONT size=3D2>&gt;Here's something I've been tossing around in my =
mind, for=20
street toy use, and I'd love to hear more from the =
group........</FONT></DIV>
<DIV><FONT size=3D2></FONT><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>&gt;Let's say you have a large displacement stroker =
motor, and=20
you desire to artificially stuff it's hunger with centrifugal =
supercharging (non=20
manufacturer specific at this &gt;point).&nbsp; The typical approach =
today would=20
be to seek out a largish single centrifugal unit that would do the dirty =
job,=20
and pulley it to gain&nbsp;the max desired&nbsp;air flow/boost at &gt;a =
specific=20
engine speed.&nbsp; This would&nbsp;net you a large diameter =
centrifugal,=20
operating at a somewhat less than maximum impeller speed, hung from one =
side of=20
your &gt;engine.&nbsp; </FONT><FONT size=3D2>This would&nbsp;work, and =
you would=20
prolly&nbsp;have a cog belt drive arrangement as a result, if you wanted =
serious=20
manifold pressure.&nbsp; Of course this will generate a new =
&gt;force/belt=20
vector load at the nose of the crank, that may or may not affect your =
front=20
bearings.&nbsp; One might even direct the output of this large =
compressor to a=20
single &gt;inter/aftercooler device for post cooling.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>&gt;Let's consider a different =
approach......</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>&gt;What about mounting two smaller centrifugals, =
low on the=20
motor, perhaps directly opposed to the crank centerline so as to cancel =
the belt=20
load vectors.&nbsp; Further imagine &gt;the discharge(s) from these =
compressors=20
being directed thru two parallel inter/aftercooler exchangers (ala: =
Porsche twin=20
turbo setups).&nbsp; The twin intercoolers might be a &gt;bit easier to =
position=20
within a street vehicle.&nbsp; At an esoteric design level, twins could =
allow a=20
person to&nbsp;fabricate an engine bay setup that has a symmetric and =
artful=20
&gt;appearance.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>&gt;Cost aside,&nbsp;does anyone see any further=20
advantages/disadvantages&nbsp;to running two slightly smaller =
compressors in=20
place of one larger unit?&nbsp; Obviously, the cost will be &gt;higher =
with=20
twins.&nbsp; I'm more wondering about airflow versus crank speed, =
throttle=20
response, boost response profile, parasitic drain at a given combined=20
flow/pressure, &gt;etc.&nbsp;&nbsp;&nbsp; </FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>&gt;Thoughts would be appreciated;</FONT></DIV>
<DIV><FONT size=3D2>&gt;Walt.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV></BODY></HTML>

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