The mathematics of the 8V vs16V problem

[jason at scirocco.org (Jason)]

At 02:07 PM 10/20/2003, Dan Bubb wrote:
>This dyno reflects my current state of tune although the mixture has been
>richened up some since then since it's alittle lean here.
>http://home.netcom.com/~jdbubb/sitebuildercontent/sitebuilderpictures/Sciroc
>co_dyno.jpg

Now that, ladies and gentlemen, is a beautiful curve.    Dan, I assume it 
took a lot of work to get to that point -- and congrats, that is by far the 
best example of a high-performance 8V I've seen.

It's interesting to compare to the 16V curve I posted earlier... You 
obviously have a quite aggressive cam in there - your HP peak is around 
6000rpm; which is where you'll find it on cammed 16Vs.  You have a nice 
torque curve.  It's only slightly less torquey at low rpms than a 16V of 
comparable HP output would be -- so not only does it breathe well, but it's 
also not miserable down low.


>Micropenis!! Ouch!

lol -- a medical term, not an insult. :)
Jason





>----- Original Message -----
>From: "Jason" <jason@scirocco.org>
>To: <scirocco-l@scirocco.org>
>Sent: Monday, October 20, 2003 12:27 PM
>Subject: RE: The mathematics of the 8Vvs16V problem
>
>
> > Heya Patrick,
> >          Thanks for posting that graph.  Your torque curve illustrates
> > exactly what I pointed out in my last mail:
> >
> > Even though your engine pushes out a very, very healthy peak of around 118
> > lb-ft of torque to the wheels, it manages only 98hp.  Exactly as I said,
> > the 8V concentrates its torque output down low in the rpm range - yours
> > peaks at around 2700rpm.  This is ideal for a daily driver -- around town
> > at leisurely rpms, your car is at its happiest.  It'll squirt off the line
> > like a beast...
> >
> > As you can see though, the torque curve peaks early and then falls off
> > gradually as you approach redline.  Horsepower is nothing more than torque
> > at high rpms.  Since your car is making relatively little torque at high
> > rpms, its Horsepower number is so much smaller.  Horsepower isn't my
> > favorite number when used to gauge the overall driveability and feel of an
> > engine, but it's the only number you need when you're talking about
>all-out
> > acceleration.  At full-tilt, if geared correctly, a 240hp, 3000lb Honda
> > with 180 lb-ft of torque will still be even with a 240hp, 3000lb V8 with
> > double the torque.
> >
> > The reason why is simple:  Under full acceleration, you're between, say,
> > 4000rpm and redline all the time... save for the initial launch, which
> > admittedly, if done properly, will be in that range, too.  Ignore what
> > happens at low revs on your chart, and you'll see why a stock 1.8 16V with
> > the same gearing will outrun your car... it puts more torque down at those
> > speeds and can rev 1000rpm more.
> >
> > Now, with that said:  Driving your car and driving that stock 1.8 16V will
> > feel completely different.  Let's say you and the 16V are puttering along
> > in 2nd gear at 2500rpm next to each other, and you both realize that your
> > two lanes are about to turn into one, and you both gun it.  The 16V will
>be
> > eating your hard-earned 8-Valve dust.
> >
> > Now, if you both kept your foot in it, the 16V would eventually catch up
> > and walk away from you.  But your subjective impression from the short
>race
> > will be of course, that your car is faster than a 16V.
> >
> > This is why I say quite clearly that the 8V is certainly not without its
> > merits.  The 8V versus 16V war is certainly akin to the V8 and big
> > displacement versus VTEC and revs debate, albeit on a lesser scale.  Flat
> > out at the 1/4 mile, the VTEC Honda can keep up with the V8s.  The reason
> > is because the high revving motor will let you take advantage of gearing,
> > where the big V8 just pulls and pulls from low revs.  You have to work
> > harder to keep up in the Honda, but if you do, you'll be rewarded with the
> > same acceleration times as the big boys.
> >
> > So yes, your car will, without a shred of doubt in my mind, be a whole lot
> > more fun around town than a 1.8 16V would.  Low-end torque is what the
> > American public wants -- that's why we have Buicks with pushrod 3800
> > V6s.  They give fantastic acceleration off idle and feel powerful, smooth,
> > and fun -- until it's time to really get moving. When it comes to the
> > stoplight race - or racetrack - or 1/4 mile track - or high speed race -
>or
> > Autobahn cruise, all of that advantage is lost, and indeed a stock 16V
> > would be faster than your fun-to-drive, torquey and happy built 8V.  It's
> > just a matter of physics... not me trying to diss ya!
> >
> > Jason
> >
> >
> >
> >
> >
> >
> >
> > At 10:40 AM 10/20/2003, ATS - Patrick Bureau wrote:
> > >jason how about this 8v (mine) I think my torque curve is quite broad,
>you
> > >got 133ft'lbs, I got 118ft'lbs torque and in the same manner of the 16v
>it
> > >instersecs the HP curve. stock JH head and 2L bottom end with only a g
>Grind
> > >in it.
> > >
> > ><http://www.longcoeur.com/scirocco/various/dyno/dyno%5Fatsgtx01%2EJPG>
> > >
> > >is this what you where looking for ? or perhaps I did not understand the
> > >question.
> > >
> > >
> > >
> > >ATS - Patrick Bureau - txrocco@sbcglobal.net
> > >----------------------------------------------
> > >MSN:ATSGTX@hotmail.com |YAHOO:ATSGTX@yahoo.com
> > >ICQ:32918816           |AIM:Texasscirocco
> > >----------------------------------------------
> > >
> > >
> > >=>-----Original Message-----
> > >=>Case in point, please see the following curve:
> > >=>http://www.scirocco16v.org/dyno/16V.jpg
> > >=>This is a dyno plot from one of our veteran list members.  It's a 2.0
>16V
> > >=>with a slightly P+P and shaved head; Schrick 260/276 cams, and an
> > >=>exhaust.  That's a relatively stock motor in my book -- the entire
>bottom
> > >=>end is completely stock.
> > >=>
> > >=>You'll see that not only does it peak out at 144whp and almost 133
>lb-ft
> > >of torque, but the torque curve itself is tremendously broad and
> > >=>beefy:  This engine puts more than 120 lb-ft of torque to the wheels
>from
> > >3000 until 6250rpm.  That is a simply awesome number from a 2-liter
> > >engine... and
> > >=>flies directly in the face of any complaints of the 16V being a dog
>down
> > >low.   And further, this particular motor puts down about the same torque
> > >=>at 2000rpm that the 1.8 16V does at its peak -- just under 100 to the
> > >wheels -- which is, as we know, more torque than any VW 8V motor
> > >=>(including the ABA) did from the factory.  So there's monumental
>high-rpm
> > >power (VR6 territory) with low rev torque besting all other VW
>4-cylinders.
> > >=>You just can't do that in an 8V VW motor.
> > >=>
> > >=>http://neubayern.net/mailman/listinfo/scirocco-l
> >
> >
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