1.8L head on 2.0L block

[MK1Scirocco16v at attbi.com (Dave Ewing)]

Along with Chris's statement, wouldn't you think that the pressure that the
piston creates when forcing the exhaust out of the cylinder is greater than
the vacuum that is created via the throttle body?  As far as exhaust is
concerned (atleast the type of exhaust that most of us are running, fairly
free flowing) I would have to say that the intake is more restrictive than
exhaust.  I realize you can increase intake flow by adding a cam or bigger
TB or whatever but it is limited to some extent or another, the exhaust on
the other hand only has to exit the head into a pipe.  It doesn't have to
pass through the air filter, intake boot, TB, intake, etc.  I don't know if
this is relevant but something that makes sense to me.

One other point to consider is that I would rather have the exhaust flow a
little better than the intake (whether the intake ports are hogged out or
not, either way) so that the heat is leaving the motor more efficiently.
16v motors run hotter due to their increased compression and the higher rpms
needed to make useable torque.

I understand the importance of velocity, speed, etc. but when you consider
that you could make a smaller port flow better than a larger port then this
would be an argument against the 1.8 head considering that the 2.0 heads are
newer and more technology has gone into the port design.  I don't know the
specifics but wouldn't you agree that VW wants to consistantly improve their
motors especially with tighter emmissions standards?

Actually, all of this is rather irrelevant as most power hungry listers have
already ported and polished their 1.8 or 2.0 heads so stock standards don't
really apply but I, again, would much rather have a newer head on my car
that hasn't seen as many miles or as many kids beating it to death.  Since
the 1.8 heads came on the scirocco/jetta/golf and the 2.0 heads only came on
the jetta/golf/passat, I'd think that the 1.8 heads on the sciroccos have
taken the most beating.

Dave
----- Original Message ----- 
From: "Chris DeLong" <green536@hotmail.com>
To: <amalventano@sc.rr.com>; <jdbubb@ix.netcom.com>;
<scirocco-l@scirocco.org>
Sent: Friday, June 27, 2003 3:52 PM
Subject: Re: 1.8L head on 2.0L block


> Ok so then you are saying that increased air velocity due to port size and
> shape DOES NOT flow more air? Hmm, I would think that INCREASED air
velocity
> would yeild more flow due to the forced induction characteristics that you
> mentioned below.
>
>
>
> Chris DeLong
> Fine Tuning
> 206.367.5503
> www.finetuningperformance.com
> Seattle, WA USA
>
>
>
>
>
> >From: "Allyn" <amalventano@sc.rr.com>
> >To: "Chris DeLong" <green536@hotmail.com>,
> ><jdbubb@ix.netcom.com>,<scirocco-l@scirocco.org>
> >Subject: Re: 1.8L head on 2.0L block
> >Date: Fri, 27 Jun 2003 14:05:54 -0400
> >
> > > More airflow=better efficiency=more power.
> >
> >umm
> >depends on runner diameter/taper / rpm
> >rpm change = different intake air pulse size/speed, therefore some
> >configurations make more power at low rpm, where some others make more
> >power
> >at higher rpm.
> >just boring the crap out of intake doesnt give you more airflow in all
> >situations. narrower intake passages cause faster air velocity while
> >filling
> >the cylinder, and that very momentum can actually cause a forced
induction
> >effect, as it squeezes that much more air in the cylinder just before the
> >intake valve closes. this is how some engines can have a volumetric
> >efficiency approaching (and possibly exceeding) a value of 1. the
narrower
> >intake is not perfect though, as it begins to restrict airflow at higher
> >rpm.
> >
> >so... from an intake perspective, a stock 1.8 head is meant to flow most
> >efficiently at a higher rpm than a stock 2.0 head is meant to.
> >Al
> >
> >
> >
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