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RE: engine decision's... I have made up my mind.

To: "Fry, Larry" <LEF@chem-tronics.com>
Subject: RE: engine decision's... I have made up my mind.
From: Brian McGarvey <brianm@zbt62.eastnet.gatech.edu>
Date: Mon, 6 Aug 2001 18:27:07 -0400 (EDT)
Cc: <scirocco-l@scirocco.org>
In-Reply-To: <2E3CDB9892E8D31181F40060080A3040010A3E7B@com.chem-tronics.com>
Sender: owner-scirocco-l@scirocco.org
On Mon, 6 Aug 2001, Fry, Larry wrote:

> Brian-
> Another fallacy.  There is nothing  to force "cold" air BACK up the pipes,
> my friend.  Even if something could, by the time the "cold" air got to the
> valves, it would not be cold enough to "shock" your grandmother, let alone
> steel components.  Sorry, but this stuff has been passed
> along for so long that people think it is the truth.  It isn't.

hmm. Me thinks he's right. Esp thinking from an Engineering point of view.
( I was repeating what my old man told me a longish time ago.,... not his
fault tho.

SO just to reason this out. If I have a very large heat sink with lots of
heat stored radiating it tho conduction of a fluid. unless you pour cold
water on it (this could be the source of the fallacy. ie. if it was
raining and you had straight pipes coming out of a flat head motor. water
gets in it and poof...

feeling dumb...



> enjoy the ride
> Larry sandiego16V
>
>
> -----Original Message-----
> From: Brian McGarvey [mailto:brianm@zbt62.eastnet.gatech.edu]
> Sent: Monday, August 06, 2001 2:12 PM
> To: Scott F. Williams
> Cc: Brian Wagner; scirocco-l@scirocco.org
> Subject: RE: engine decision's... I have made up my mind.
>
>
> Ok.
> >From the wonderful world of Motorcycles and Really fast really tiny four
> cyln. The problem with zero back pressure is a simple one of temperature.
> Very similar to pouring cold water into an over heated engine. If you have
> zero back pressure possible with only a very staight short pipe as the
> motor is heated up and the exhaust is forced out the short pipe in bursts
> the cool air rushes back in and the temp shock of the "cold" air vs hot
> metal and that would be how you get bent/broken/shattered parts. IFRC.
> brian
>
>
>  On Mon, 6 Aug 2001, Scott F. Williams wrote:
>
> > It isn't the back pressure that makes more torque. It is the proper port
> > velocity and properly tuned acoustics in the exhaust system. A shock wave
> > blasts out of the combustion chambers with each exhaust pulse. Once it
> hits
> > an obstruction, a bend, or other pulse, the wave then reflects backwards
> and
> > pushes any unburned fuel and air mixture back into the combustion chamber.
> > This also promotes greater chamber fill and thusly more low-end torque.
> >
> > Someone educate me about the burnt valves thing, though. I forget why that
> > happens. Is it because you've got oxygen hitting red-hot metal?
> > ______________________________
> > Scott F. Williams
> > Account Manager
> > GENUiTY - Eastern Region
> > 100 Wall Street, 10th Floor
> > New York, NY 10005
> > Voice: 212.416.1745
> > Cell: 917.648.2256
> > Fax: 212.618.5160
> > scott.williams@genuity.com
> >
> > > -----Original Message-----
> > > From: owner-scirocco-l@scirocco.org
> > > [mailto:owner-scirocco-l@scirocco.org]On Behalf Of Brian Wagner
> > > Sent: Monday, August 06, 2001 4:44 PM
> > > To: sfwilliams@home.com; Josh.Hignight@phoenix.edu
> > > Cc: scirocco-l@scirocco.org
> > > Subject: RE: engine decision's... I have made up my mind.
> > >
> > >
> > > BP is essential to the life of the engine, without it you will get burnt
> > > valves and a top end.
> > >
> > > Brian
> > >
> > > 88 16v
> > > 87 16v
> > > 86 8v (sold to neighbor)
> > >
> > >
> > >
> > > >From: "Scott F. Williams" <sfwilliams@home.com>
> > > >To: "Josh Hignight" <Josh.Hignight@phoenix.edu>
> > > >CC: "scirocco List" <scirocco-l@scirocco.org>
> > > >Subject: RE: engine decision's... I have made up my mind.
> > > >Date: Mon, 6 Aug 2001 16:27:15 -0400
> > > >
> > > >Okay, you got me there. Let's say that no *4-stroke* motor needs
> > > >backpressure. :^)
> > > >______________________________
> > > >Scott F. Williams
> > > >Account Manager
> > > >GENUiTY - Eastern Region
> > > >100 Wall Street, 10th Floor
> > > >New York, NY 10005
> > > >Voice: 212.416.1745
> > > >Cell: 917.648.2256
> > > >Fax: 212.618.5160
> > > >scott.williams@genuity.com
> > > >
> > > > > -----Original Message-----
> > > > > From: owner-scirocco-l@scirocco.org
> > > > > [mailto:owner-scirocco-l@scirocco.org]On Behalf Of Josh Hignight
> > > > > Sent: Monday, August 06, 2001 4:15 PM
> > > > > Cc: scirocco List
> > > > > Subject: RE: engine decision's... I have made up my mind.
> > > > >
> > > > >
> > > > > Umm, 2-strokes benefit from backpressure. Since most 2-stroke
> > > > > engines don't
> > > > > have mechanical valves, the back pressure helps to eliminate
> blow-by,
> > > >thus
> > > > > increasing power because it maintains that there is a mixture to
> > > > > burn in the
> > > > > chamber (Hence the reason my r/c car barely runs when the pipe
> > > > > falls off).
> > > > >
> > > > > But that's beside the point when it comes to dubs. Just thought
> > > > > I'd mention
> > > > > it.
> > > > >
> > > > > Joshua Hignight
> > > > > Student Services/Technical Services
> > > > > New Mexico Campus
> > > > > (505) 821-4800
> > > > >
> > > > >  -----Original Message-----
> > > > > From: 	Scott F. Williams [mailto:sfwilliams@home.com]
> > > > > Sent:	Monday, August 06, 2001 1:11 PM
> > > > > To:	jdbubb@ix.netcom.com; Neal Tovsen
> > > > > Cc:	scirocco List
> > > > > Subject:	RE: engine decision's... I have made up my mind.
> > > > >
> > > > > Let's kill the myth that backpressure helps an engine. NO ENGINE
> > > >BENEFITS
> > > > > FROM RESTRICTION IN THE EXHAUST SYSTEM! The reason normally
> aspirated
> > > > > engines may gain more torqe with a smaller diameter exhast,
> > > is because
> > > >the
> > > > > higher velocity in the system creates a greater scavenging
> > > effect that
> > > >in
> > > > > turn allows for cleaner combustion chambers, wich means more
> air-fuel
> > > > > mixture per stroke, which means more power.
> > > > >
> > > > > Zero backpressure is always the ideal. Complete scavenging and
> > > > > high exhaust
> > > > > velocity are always the goal.
> > > > > ______________________________
> > > > > Scott F. Williams
> > > > > Account Manager
> > > > > GENUiTY - Eastern Region
> > > > > 100 Wall Street, 10th Floor
> > > > > New York, NY 10005
> > > > > Voice: 212.416.1745
> > > > > Cell: 917.648.2256
> > > > > Fax: 212.618.5160
> > > > > scott.williams@genuity.com
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: owner-scirocco-l@scirocco.org
> > > > > > [mailto:owner-scirocco-l@scirocco.org]On Behalf Of Dan Bubb
> > > > > > Sent: Monday, August 06, 2001 2:55 PM
> > > > > > To: Neal Tovsen
> > > > > > Cc: Patrick Bureau; scirocco List
> > > > > > Subject: Re: engine decision's... I have made up my mind.
> > > > > >
> > > > > >
> > > > > > somebody, please somebody explain this BS about lower backpressure
> > > > > > causing loss of power!
> > > > > >
> > > > > > Neal Tovsen wrote:
> > > > > > >
> > > > > > > > 2.5" Pipping finishined with stainless Remus or Borla
> > > Muffler.(to
> > > >be
> > > > > > > > decided)
> > > > > > >
> > > > > > > Did you mean 2.25"? 2.5" is pretty damn HUGE for a N/A 2.0L
> > > > > engine. With
> > > > > > > such a loss of backpressure, you might actually lose power.
> > > > > Since you're
> > > > > > > ordering the manifold/downpipe from TT, you could go with their
> > > >2.25"
> > > > > > > exhaust system with a Borla for a sweet full setup.
> > > > > > >
> > > > > > > Looks like a screamin' setup otherwise. Go for it!
> > > > > > >
> > > > > > > Neal
> > > > > > >
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