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Velocity and Scavenging...myth?
Posted by Chad [Email] (more from Chad) on Wed, 31 Jan 2007 06:41:03
In Reply to: Re: Performance with muffler/ without!!!!!!!, SWEDISH DYNAMICS, Tue, 30 Jan 2007 15:37:32
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There are two tings that I've heard repeated by the novice and the expert alike...
"Turbos like to be as open as possible"
"An exhaust that is too big will reduce back pressure, drop velocity and eliminate the scavenging effects that will hurt your low end, especially on N/A's"
I've done much reading on the subject, both anectdotal and scientific. I've heard of 2.0L n/a's gaining power everywear by moving too 3" exhaust and 2.0 turbo's losing power by going to 3"....
The answer of come up with is "it depends"
The reason that people have different experiences has to do with one thing...tuning. Ignition advance is set to a certain target, most vehicles will retard under knock, but few will advance if the conditions seem optimal. Exhaust back pressure and ignition timing are very closely related. Basically any turbo that loses response and power from opening up the exhaust can have it's timing advanced to maximize the new flow and will respond with decreased spool and better power.
Scavenging has more to do with headers, where proper length and width in the primaries, as well as careful design of the merge collector can make a big difference in terms of balancing high and low end power.
Posts in this Thread:
- Performance with muffler/ without!!!!!!!, Aerohead
, Tue, 30 Jan 2007 14:34:02- Re: Performance with muffler/ without revealed..., matsuda, Thu, 8 Feb 2007 17:08:15
- Re: Performance with muffler/ without!!!!!!!, SWEDISH DYNAMICS, Tue, 30 Jan 2007 15:37:32
- Velocity and Scavenging...myth?, Chad, Wed, 31 Jan 2007 06:41:03 <-- Viewing This Message
- Scavenging is for increasing the VE of N/A engines..., Jonathan Scupin
, Thu, 1 Feb 2007 20:02:39- Re: Scavenging is for increasing the VE of N/A engines..., Aerohead
, Fri, 2 Feb 2007 16:00:05 - Yea, but the engines are na until the turbo spools!, John Williams
, Fri, 2 Feb 2007 12:00:27- they're really not, TML
, Sun, 4 Feb 2007 13:50:18 - Re: Yea, but the engines are na until the turbo spools!, Chad, Fri, 2 Feb 2007 12:27:43
- good point, John!, Jonathan Scupin
, Fri, 2 Feb 2007 12:18:40
- Re: Scavenging is for increasing the VE of N/A engines..., Chad, Fri, 2 Feb 2007 07:23:52
- Heady stuff, turbocon86, Wed, 31 Jan 2007 08:41:45
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