hey no problem, that's what I'm here for.
-- Canuck-------------------------------------------- Y2K 4.7L 2wd 5spd ""crm"" <tb.crm@verizon.net> wrote in message news:009501c207f0$92cd78c0$7c6445a1@vatican2... > > wow, excellent explanation...thats what i was looking for! > > thanks > > -adam > > ----- Original Message ----- > From: "Canucker Trucker" <mal5@ualberta.ca> > To: <dakota-truck-moderator@bent.twistedbits.net> > Sent: Thursday, May 30, 2002 9:59 AM > Subject: Re: DML: Exhaust bottleneck? ATTN CRM > > > > > > Hey CRM, I'm not sure if someone answered this question for you yet, but I > > couldn't find a reply to it. So here goes nothing: > > > > Scavenging 101 > > When your exhaust leaves your manifold (or header) it comes out in a > > 'pulse'. This is due to the piston moving up and forcing the exhaust out, > > then the exhaust valve slamming shut. Basically what this pulse is, is a > > high pressure node in your exhaust 'wave'. If you remember back to high > > school physics (and I know, its tough) recall the experiment with the > > slinky. If you held the slinky tight, and gave it a flick at one end, > you'd > > see a pulse travel down the end and back. Now suppose this slinky is your > > exhaust piping. As the pulse travels down, there is a low pressure area > > just behind it. The whole concept of scavenging is for the 'pulse' from > the > > OTHER header to be 'sucked' along by the low pressure pocket just behind > the > > first pulse. The only way to do this is to connect the two headers (via > an > > 'h' or 'x' pipe). This allows pressure communication between the two > > systems. The 'x' pipe is preffered over the 'h' pipe because it has less > > flow impedence. Scavenging is only effective at low RPMs when the exhaust > > is still being sent in pulses ... at high RPMs the exhaust flow is > > essentially uniform and not affected by the pulsing affect (i.e. the > pulses > > are so close together they might as well be a continuous flow). > > > > I hope that explains it a bit better ... now Tuned Length exhaust is a > > different story ... let me know if you want to know about that. :) > > > > -- > > Canuck > > -------------------------------------------- > > Y2K 4.7L 2wd 5spd > > > > > > > > If you are planning for modded truck then go with the 3-inch to the > rear > > > for > > > > a single exhaust and 2.25inch sounds good but add a 'X' pipe (Gibson > > > design) > > > > for a cross-over between the exhaust for back scavenging and a balance > > > > exhaust flow. > > > > > > Okay, pardon the ignorance, but what exactly is "back scavenging"? I've > > seen > > > that term tossed around but dont really understand what it is. Also, > since > > > this is just a dual exit, not a true dual from the headers, would I > really > > > need an X or H pipe? > > > > >
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