I don't think I support that theory, if I recall correctly a simple approximation to the ammount of a fluid (or gas) that can flow through a pipe of a certain diameter is proportional to the crossection of the pipe - ie the bigger the pipe, the more fluid you can flow. For a set ammount of flow a liquid will certainly flow faster through a smaller diameter pipe, however faster flow will lead in general to higher friction - ie more backpressure. The design of the extractors is certainly going to have a big effect like Brad said. Out of curiosity I wonder if the weight makes much difference? Assuming the wall thicknesses are the same a 3" exhaust is going to weigh twice that of a 1.5" exhaust - may not be much in it though.
On Tue, 2004-04-27 at 16:12, maldat wrote: > I use 4-1 headers that are quite long, the 4-1 collector is just about > under the seat. > I also use a exhast thats one size down from 2"..everyone else had 2+" > and my car was faster..?? > > Malcolm > "new theory, you can move more air quicker thru a smaller pi[pe than a > big one.... what do you guys think of that?. > > ----- Original Message ----- > From: Jeff Oldham > To: [EMAIL PROTECTED] > Sent: Tuesday, April 27, 2004 1:51 PM > Subject: RE: exhausts questions > > There is some debate about exhausts being too big & not > providing enough back pressure. > But i think its only the first part of your exhaust (the > headers) that affect this. > that why some new exhaust systems run variable exhaust > manifolds as it affects your torque at various revs. > > go to about halfway down on this web page for some info. > > http://www.autospeed.com/cms/A_46/article.html > > > I am running 4-2-1 motivator extractors into 2 1/2 with 3" > tail pipe & turbo muffler. > the 4-2-1 (or "y" extractors) give a slightly more spread > torque range than 4-1 > I think 2 1/2 inches is biggest that will fit in the rear > cross member of a 510 > without enlarging the hole :) > > When i got rid of the bit of curtain rod that was on my car i > noticed not more power > but that the engine felt like it could rev out further easier. > > BUT i could have it all wrong so ask some professionals :-) > cheers Jeff > > > > > > > > > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf > Of kla > Sent: Sunday, April 25, 2004 12:47 AM > To: [EMAIL PROTECTED] > Subject: exhausts questions > > > I've been wondering about sports exhausts, as i was > thinking of getting a system installed (extractors to > the back) > and i was wandering. as a general rule. sizes. > obviously too small means not enough flow, but what > about big? > what happens when you get too big, and what is > generally the best size for a 1.5litre (standard, > non-turbo etc.) > if its too big do you get a dead space effect where it > cant move enough of the air or what? > cheers. > > --membersozdat------------------------------------------------------- > OZDAT Mailing List Please Note:- > Send (un)subscribe requests to > [EMAIL PROTECTED] > Send submissions to [EMAIL PROTECTED] > No unauthorised redistribution of this email > http://www.ozdat.com/ozdatonline/index.htm > http://www.ozdat.com/ozdatonline/listindex.html > http://www.mail-archive.com/[EMAIL PROTECTED]/ > --------------------------------------------------------------------- > > --membersozdat------------------------------------------------------- > OZDAT Mailing List Please Note:- > Send (un)subscribe requests to [EMAIL PROTECTED] > Send submissions to [EMAIL PROTECTED] > No unauthorised redistribution of this email > http://www.ozdat.com/ozdatonline/index.htm > http://www.ozdat.com/ozdatonline/listindex.html > http://www.mail-archive.com/[EMAIL PROTECTED]/ > --------------------------------------------------------------------- > > --membersozdat------------------------------------------------------- > OZDAT Mailing List Please Note:- > Send (un)subscribe requests to [EMAIL PROTECTED] > Send submissions to [EMAIL PROTECTED] > No unauthorised redistribution of this email > http://www.ozdat.com/ozdatonline/index.htm > http://www.ozdat.com/ozdatonline/listindex.html > http://www.mail-archive.com/[EMAIL PROTECTED]/ > --------------------------------------------------------------------- --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[EMAIL PROTECTED]/ ---------------------------------------------------------------------
