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Back pressure; was Re: got my 2.5" centre pipe!
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Neither does a gasoline engine (need overlap).
They have it because that's how you make power.
(something a diesel does not have....)
:)
Larry
----- Original Message -----=20
From: Rick Alexander=20
To: The list=20
Sent: Thursday, March 13, 2003 8:48 AM
Subject: Re: Back pressure; was Re: got my 2.5" centre pipe!
Might I interject that it also has to do with valve overlap. The cams
(diesel vs. gas) have very little in common. A diesel needs no (or =
very
little) overlap.
Rick Alexander
----- Original Message -----
From: "Andrew Basterfield" <list@cemetery.homeunix.org>
To: "Dan Bubb" <jdbubb@ix.netcom.com>
Cc: <drew@scirocco.cs.uoguelph.ca>; <skerocdriver@juno.com>;
<scirocco-l@scirocco.org>
Sent: Thursday, March 13, 2003 11:04 AM
Subject: Re: Back pressure; was Re: got my 2.5" centre pipe!
> On Thu, 13 Mar 2003 10:53:20 -0500
> "Dan Bubb" <jdbubb@ix.netcom.com> wrote:
>
> > Can you elaborate on this statement about why gas motors need
> > backpressure and how this is related to being throttled.
>
> Gas motors need back pressure because the factory fuelling and =
ignition
> maps are set up with the standard air intake and exhaust system. =
These
> are restrictive to make them quiet. Gas motors need tightly =
controlled
> air/fuel ratio or they run like a pig with terrible emissions and =
fuel
> consumption. Also, if you make the mixture richer you need more =
advance
> because it burns slower, so it is all inter-related.
>
> Diesel motors aren't overly worried about the mixture, you throttle =
a
> diesel motor by squirting in more fuel if you want it to go faster =
or
> cutting back on the fuel if you want it to go slower. There is no
> throttle butterfly to limit air flow, you just vary the fuel flow. =
There
> is no ignition to worry about, of course. Because of the way diesel
> burns the mixture strength doesn't have such an effect on the motor
> performance in general.
>
> --Andrew
>
> _______________________________________________
> Scirocco-l mailing list
> Scirocco-l@scirocco.org
> http://neubayern.net/mailman/listinfo/scirocco-l
_______________________________________________
Scirocco-l mailing list
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<DIV><FONT face=3DArial size=3D2>Neither does a gasoline engine (need=20
overlap).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>They have it because that's how you =
make=20
power.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>(something a diesel does not =
have....)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>:)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Larry</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-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 href=3D"mailto:ralexander03@snet.net"; =
title=3Dralexander03@snet.net>Rick=20
Alexander</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A=20
href=3D"mailto:scirocco-l@scirocco.org"; =
title=3Dscirocco-l@scirocco.org>The=20
list</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, March 13, 2003 =
8:48=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: Back pressure; was =
Re: got=20
my 2.5" centre pipe!</DIV>
<DIV><BR></DIV>Might I interject that it also has to do with valve =
overlap.=20
The cams<BR>(diesel vs. gas) have very little in common. A diesel =
needs no (or=20
very<BR>little) overlap.<BR><BR>Rick Alexander<BR><BR>----- Original =
Message=20
-----<BR>From: "Andrew Basterfield" <<A=20
=
href=3D"mailto:list@cemetery.homeunix.org";>list@cemetery.homeunix.org</A>=
><BR>To:=20
"Dan Bubb" <<A=20
=
href=3D"mailto:jdbubb@ix.netcom.com";>jdbubb@ix.netcom.com</A>><BR>Cc: =
<<A=20
=
href=3D"mailto:drew@scirocco.cs.uoguelph.ca";>drew@scirocco.cs.uoguelph.ca=
</A>>;=20
<<A=20
=
href=3D"mailto:skerocdriver@juno.com";>skerocdriver@juno.com</A>>;<BR>&=
lt;<A=20
=
href=3D"mailto:scirocco-l@scirocco.org";>scirocco-l@scirocco.org</A>><B=
R>Sent:=20
Thursday, March 13, 2003 11:04 AM<BR>Subject: Re: Back pressure; was =
Re: got=20
my 2.5" centre pipe!<BR><BR><BR>> On Thu, 13 Mar 2003 10:53:20=20
-0500<BR>> "Dan Bubb" <<A=20
href=3D"mailto:jdbubb@ix.netcom.com";>jdbubb@ix.netcom.com</A>>=20
wrote:<BR>><BR>> > Can you elaborate on this statement about =
why gas=20
motors need<BR>> > backpressure and how this is related to being =
throttled.<BR>><BR>> Gas motors need back pressure because the =
factory=20
fuelling and ignition<BR>> maps are set up with the standard air =
intake and=20
exhaust system. These<BR>> are restrictive to make them quiet. Gas =
motors=20
need tightly controlled<BR>> air/fuel ratio or they run like a pig =
with=20
terrible emissions and fuel<BR>> consumption. Also, if you make the =
mixture=20
richer you need more advance<BR>> because it burns slower, so it is =
all=20
inter-related.<BR>><BR>> Diesel motors aren't overly worried =
about the=20
mixture, you throttle a<BR>> diesel motor by squirting in more fuel =
if you=20
want it to go faster or<BR>> cutting back on the fuel if you want =
it to go=20
slower. There is no<BR>> throttle butterfly to limit air flow, you =
just=20
vary the fuel flow. There<BR>> is no ignition to worry about, of =
course.=20
Because of the way diesel<BR>> burns the mixture strength doesn't =
have such=20
an effect on the motor<BR>> performance in general.<BR>><BR>> =
--Andrew<BR>><BR>>=20
_______________________________________________<BR>> Scirocco-l =
mailing=20
list<BR>> <A=20
=
href=3D"mailto:Scirocco-l@scirocco.org";>Scirocco-l@scirocco.org</A><BR>&g=
t; <A=20
=
href=3D"http://neubayern.net/mailman/listinfo/scirocco-l";>http://neubayer=
n.net/mailman/listinfo/scirocco-l</A><BR><BR><BR>________________________=
_______________________<BR>Scirocco-l=20
mailing list<BR><A=20
=
href=3D"mailto:Scirocco-l@scirocco.org";>Scirocco-l@scirocco.org</A><BR><A=
=20
=
href=3D"http://neubayern.net/mailman/listinfo/scirocco-l";>http://neubayer=
n.net/mailman/listinfo/scirocco-l</A><BR></BLOCKQUOTE></BODY></HTML>
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