[Diy_efi] formulas for CFM rates

Oolan Zimmer ozimmer at softhome.net
Tue Dec 16 01:00:24 GMT 2003


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MessageIt's more complicated than just bore size, you need to consider =
changes in air velocity too.

I would guess somewhere around 600 CFM for a 75mm throttle body.  But =
again, other things influencing turbulence and air velocity will have =
the biggest impact here.

Oolan Zimmer
ozimmer at softhome.net


  ----- Original Message -----=20
  From: Mark Linder=20
  To: 'A list for Do-It-Yourself EFI'=20
  Sent: Monday, December 15, 2003 6:34 PM
  Subject: RE: [Diy_efi] formulas for CFM rates


  Sorry, I should have been more specific - I need to calculate the CFM =
of air through a throttle body.


  Thanks!

  Mark
    -----Original Message-----
    From: diy_efi-bounces at diy-efi.org =
[mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Oolan Zimmer
    Sent: Monday, December 15, 2003 4:18 PM
    To: A list for Do-It-Yourself EFI
    Subject: Re: [Diy_efi] formulas for CFM rates


    Isn't the CFM of a 4-cycle engine just the displacement/2 x RPM?  1 =
liter =3D .0353147 CF.

    Oolan Zimmer
    ozimmer at softhome.net

      ----- Original Message -----=20
      From: Mark Linder=20
      To: diy_efi at diy-efi.org=20
      Sent: Monday, December 15, 2003 5:50 PM
      Subject: [Diy_efi] formulas for CFM rates


      Back on the old list someone had posted the formula for =
calculating CFM based on bore size.  Does anyone have that formula?

      Also, if anyone knows the CFM rating of a 75mm Mustang style =
throttle body, please post it.

      Thanks!

      Mark



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<DIV><FONT face=3DArial size=3D2>It's more complicated than just bore =
size, you need=20
to consider changes in air velocity too.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>I would guess somewhere around 600 CFM =
for a 75mm=20
throttle body.&nbsp; But again, other things influencing turbulence and =
air=20
velocity will have the biggest impact here.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Oolan Zimmer</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><A=20
href=3D"mailto:ozimmer at softhome.net">ozimmer at softhome.net</A></FONT></DIV=
>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3Dmark.linder at verizon.net =
href=3D"mailto:mark.linder at verizon.net">Mark=20
  Linder</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Ddiy_efi at diy-efi.org=20
  href=3D"mailto:diy_efi at diy-efi.org">'A list for Do-It-Yourself =
EFI'</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, December 15, 2003 =
6:34=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> RE: [Diy_efi] formulas =
for CFM=20
  rates</DIV>
  <DIV><BR></DIV>
  <DIV><SPAN class=3D414163300-16122003><FONT face=3DArial =
color=3D#0000ff=20
  size=3D2>Sorry, I should have been more specific - I need to calculate =
the=20
  CFM&nbsp;of air through a throttle body.</FONT></SPAN></DIV>
  <DIV><FONT face=3DArial color=3D#0000ff size=3D2></FONT>&nbsp;</DIV>
  <DIV>&nbsp;</DIV>
  <DIV align=3Dleft><FONT face=3DArial color=3D#0000ff =
size=3D2>Thanks!</FONT></DIV>
  <DIV align=3Dleft><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT>&nbsp;</DIV>
  <DIV align=3Dleft><FONT face=3DArial color=3D#0000ff =
size=3D2>Mark</FONT></DIV>
  <BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
    <DIV></DIV>
    <DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr =
align=3Dleft><FONT=20
    face=3DTahoma size=3D2>-----Original Message-----<BR><B>From:</B> <A =

    =
href=3D"mailto:diy_efi-bounces at diy-efi.org">diy_efi-bounces at diy-efi.org</=
A>=20
    [mailto:diy_efi-bounces at diy-efi.org] <B>On Behalf Of </B>Oolan=20
    Zimmer<BR><B>Sent:</B> Monday, December 15, 2003 4:18 =
PM<BR><B>To:</B> A=20
    list for Do-It-Yourself EFI<BR><B>Subject:</B> Re: [Diy_efi] =
formulas for=20
    CFM rates<BR><BR></FONT></DIV>
    <DIV><FONT face=3DArial size=3D2>Isn't the CFM of a =
4-cycle&nbsp;engine just the=20
    displacement/2 x RPM?&nbsp; 1 liter =3D .0353147 CF.</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <DIV><FONT face=3DArial size=3D2>Oolan Zimmer</FONT></DIV>
    <DIV><FONT face=3DArial size=3D2><A=20
    =
href=3D"mailto:ozimmer at softhome.net">ozimmer at softhome.net</A></FONT></DIV=
>
    <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
    <BLOCKQUOTE=20
    style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
      <DIV style=3D"FONT: 10pt arial">----- Original Message ----- =
</DIV>
      <DIV=20
      style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
      <A title=3Dmark.linder at verizon.net=20
      href=3D"mailto:mark.linder at verizon.net">Mark Linder</A> </DIV>
      <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Ddiy_efi at diy-efi.org=20
      href=3D"mailto:diy_efi at diy-efi.org">diy_efi at diy-efi.org</A> </DIV>
      <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, December 15, =
2003 5:50=20
      PM</DIV>
      <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [Diy_efi] formulas =
for CFM=20
      rates</DIV>
      <DIV><BR></DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN =
class=3D938244723-15122003>Back on the=20
      old list someone had posted the formula for calculating CFM based =
on bore=20
      size.&nbsp; Does anyone have that formula?</SPAN></FONT></DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN=20
      class=3D938244723-15122003></SPAN></FONT>&nbsp;</DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN =
class=3D938244723-15122003>Also, if=20
      anyone knows the CFM rating of a 75mm Mustang style throttle body, =
please=20
      post it.</SPAN></FONT></DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN=20
      class=3D938244723-15122003></SPAN></FONT>&nbsp;</DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN=20
      class=3D938244723-15122003>Thanks!</SPAN></FONT></DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN=20
      class=3D938244723-15122003></SPAN></FONT>&nbsp;</DIV>
      <DIV><FONT face=3DArial size=3D2><SPAN=20
      class=3D938244723-15122003>Mark</SPAN></FONT></DIV>
      <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
      <DIV align=3Dleft>
      <DIV align=3Dleft><FONT face=3DArial size=3D2><A=20
      href=3D"http://www.newsolutionsnw.com/"></A></FONT></DIV></DIV>
      <P>
      <HR>

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