Date: Fri, 17 Sep 2004 10:31:37 +0200
Reply-To: Calle Fallberg <calle.fallberg@TELIA.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Calle Fallberg <calle.fallberg@TELIA.COM>
Subject: Re: Exhaust Pipe Question
Content-Type: text/plain; charset="iso-8859-1"
So if you put a fat-ass exhaust system on any car, you´ll get better torque,
power and mileage but still keep the same noice level ?
Amazing that the automotive industry has been building cars for over a
hundred years, fighting for one period (late 60´s - early 70´s ) to get the
highest hp ratings and the last ten years or so with getting the mileage up
thus meeting the demands from the environmentalists and nobody has ever
discovered this simple solution !
OK, if you´re ready to put a load of cash in you could get a new exhaust
tuned in for your car but hey, wasn´t the original question on where to find
a cheap aftermarket exhaust ??
Calle
-----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Dennis
> Sent: Thursday, September 16, 2004 6:16 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Exhaust Pipe Question
>
>
> I would disagree. A properly designed exhaust has low or no
> backpressure. On the contrary, by taking advantage of resonant pressure
> waves, a vacuum is actually created at the exhaust valves. Essentially
> the pressure front from the closing of one valve travels down the header
> pipe around the collector and then back up the next primary tube .. and
> bounces off the next exhaust valve about to open. At that point you may
> actually have a vacuum at the valve resulting in increased scavenging,
> decreased pumping loss, and thus better efficiency.
>
> I won't rehash the volumes of information out there on exhaust theory
> but tube diameter, primary tube length and collector location all
> require careful consideration to ensure both high gas velocity and the
> aforementioned resonant effect. It's important to note that this tuning
> is generally focussed to a particular engine's planned power curve.
>
> Check out the dyno tests at www.techtonicstuning.com
>
> A quick intro to the theory:
> http://www.powerflowsystems.com/review/12-00.shtml
>
> A properly designed exhaust means better torque, hp, and mileage. A
> good example is my daily driver car. It started life as a 90hp 1.8L VW
> Scirroco that maxed at about 35mpg (imperial). It now has a tuned 2.0
> litre that delivers 145 HP, yet still delivers 39mpg (imperial) at 60mph
> highway cruise. It's all about efficiency...and internal combustion
> engines (particularly older ones) have lots of room for improvement.
>
> My site http://my.tbaytel.net/guskers has a section on exhaust with
> references to autospeed's muffler tests. It is possible to have a quiet
> exhaust with straight through mufflers if designed properly. The
> exhaust I designed has two straight through mufflers, one five inch OD,
> and one six inch OD. It is only slightly louder than stock...although
> the first design with a smaller OD 2nd muffler was obnoxiously loud.
>
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