Date:         Fri, 12 Oct 2001 05:13:34 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Torque Curves for Key Vanagon Swap Candidates
Content-Type: text/plain; charset="US-ASCII"

Gentlemen and Ladies,

For some time there has been an ongoing philosophical discussion as to the
best engine swap possibility as well as intangible discussions of the
propulsive merits of the stock versions. I have maintained, in a similar
polemic vein, that everything is straightforward and understandable if one
compares the torque curves for the various possibilities, scale those curves
by the leverage generated through the transmission and wheel combination and
compare these values to the force needed to propel the typical Westfalia
through the ether.

As I have said, torque is everything (next to the engine fuel efficiency map)
to understanding the performance of these vehicles. Well, anyway, for some
time, I have collected the engine performance curves from VAG technical
publications. I'll publish the references if anyone wants to know.

Back to the point. I have collected the horsepower, torque and fuel
consumption maps for the 8V 1.8L Digifant, the 2.1L Waterboxer, the 1.9L
Waterboxer, the 2.0L Air-cooled boxer, the Vanagon 1.6L Diesel, the Vanagon
1.6L TurboDiesel, the 2.0L Audi 3A, and the Turbocharged Audi 3A nee SAAB
2.0L Turbo. I have digitized the curves (all representing flywheel torque)
and plotted them together in a series of plots for direct comparison. The
plots are available to any hardy soul who sends an email request.

The data is quite interesting. Obviously the diesel is at the bottom of the
pack in torque, but the curves for the 1.6L turbo diesel and the 2.0L
gasoline air-cooled version are essentially identical. When coupled with the
transmission gearing, the 1.6L TD clearly out performs the air-cooled
version. The 1.9L waterboxer outperforms the A/C engine, but is significantly
inferior to the I-4 1.8L 8V engine. However, the 2.1L waterboxer is a
credible performer clearly outdoing the 1.8L I-4. The curve for the Audi 3A
2.0L which should be representative of the ABA block and the SA/TIICO
offering is stronger than the 2.1L WB, but not by much. Of course the Turbo
Audi 3A blows them all out of the petroleum.

BUT the curves show that the so-called lack of low end torque on the part of
the I-4 engines is a function of displacement only. The 1.8L I-4 engine has
identical low speed torque as compared to the 1.9L WB, and puts out more umph
at higher RPM. Likewise, thank you, for the 2.1L WB as compared to the 2.0L
I-4 blocks. Of course the Waterboxers may have been already sucking water on
the dyno for these tests (extra power through OH assist!).

Furthermore, when you take into account the drive train leverage, the 1.8L
I-4 engine mounted with the Diesel trans has significantly more torque on the
road as compared to the stock 2.1L WB. Putting the 1.8L I-4 in a vehicle with
a WB or AC transmission reduces the available thrust to that of the 1.9L WB
versions. The impact of switching from 185-14 tires to 215/75-15's represents
a drop in torque of 8.7% depending on brand (I'm comparing Michelin to
Yokohama Geolanders).

So how much performance will you lose switching to the larger tires in your
misguided attempt to reduce wear and increase fuel economy? The Sanden Air
Conditioning compressor requires more than 8 HP at 4000 rpm. So, if you want
a pretest of the performance hit, run out with your friendly
van-o-box-on-wheels, take 'er up to 55 mph and turn the AC on! The kick in
the slats will show you the importance of those ponies. Remember, 37 kW to
move the Vanagon through the air at 60 mph.

I also have curves for thrust at the wheel, as well as HP and real fuel
consumption. No data for the Subaru crowd, the Chevy or Buick group, the Audi
V6, the VR6 gang or the Mazda Rotary crew

Hope someone finds this as entertaining as I did.

Frank Grunthaner