A lot of todays motorbikes have exhausts that go from 4 down to two down to one (low down torque), then this flap opens and it is a 4 into one for high reving?? (something l;ike that)
My mates bike has this setup, it also has a flap in the airbox, that when low revs, the airbox is somewhere close to being 1/2 the high rev size. Very interesting stuff, but I would hate to be trying to get parts for it in 10 years time. Rick White. ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, April 27, 2004 4:48 PM Subject: Re: exhausts questions > Mazda actually did something similar with the RX7's where they had both a > pea-shooter exhaust and a big monster exhaust system on the same car, and > there was a lever or a switch in the cabin that let you change between the > two, so you could have great economy with crap performance, or crap economy > with awesome performance. > > As an offshoot, mazda were also tinkering with variable length tuned inlet > runners on their racecars, the inlets were two pipes one inside the other > that slid in and out to make the runners long at low rpm and as the revs > climbed the runners got shorter and shorter. This gave them some fantastic > torque capability right thru the rev range. > Very clever stuff at the time, but I think it got outlawed because of some > stupid rule or another. > > There's a lot to be said on the subject of variable lengths and tube sizes > both inlet and exhaust. Unless you have a few million dollars backing you > with scientific testing, you can only do what we all do and settle on a > happy medium. > > > ----- Original Message ----- > From: "Richard Webb" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Tuesday, April 27, 2004 6:15 PM > Subject: Re: exhausts questions > > > > > > > > > > > > I'm sure I read on autospeed or somewhere about flanges to make your > > exhaust effectively smaller. It was something to do with noise but if > > Geordies theory is correct this would be great to have to progressively > > open as the rpm's increase. Anyone know of such a system? or would the > > complexity of it outweigh (literally) the benefits? > > > > > > > > > > From: [EMAIL PROTECTED]@datascribe.com.au on 27/04/2004 16:48 > > ZE10 > > > > Please respond to [EMAIL PROTECTED] > > > > Sent by: [EMAIL PROTECTED] > > > > > > > > To: <[EMAIL PROTECTED]> > > > > > > cc: > > > > > > > > > > > > > > Subjec Re: exhausts questions > > t: > > > > > > > > > > > > > > > > > > No scientific basis here, but I am under the impression there is an > optimum > > pipe size for flow > > too small and it's restrictive, too large and you don't get the air speed > > you need. > > > > Ideally, you would have a small pipe for low rpm and a larger pipe for > > higher rpm when more gas needs to flow. and everything inbetween but we > all > > know that pipes can not change size all by themselves :D > > > > So a typical exhaust system is a compromise of some sort, whether it is > > midrange pipe size optimised for midrange power or larger pipe size > > optimised for high end power. > > > > ----- Original Message ----- > > From: maldat > > To: [EMAIL PROTECTED] > > Sent: Tuesday, April 27, 2004 4:12 PM > > Subject: Re: exhausts questions > > > > 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]/ > > --------------------------------------------------------------------- > > > > > > > > > > > > > > > > > > > --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]/ ---------------------------------------------------------------------
