the mk3`s two.slow nickname is well earned, but bahn brenner aims

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WORDS & PHOTOS
SAM DU
THE MK3’S TWO.SLOW
NICKNAME IS WELL EARNED,
BUT BAHN BRENNER AIMS TO
ERADICATE THIS SLUR WITH AN
AFFORDABLE SUPERCHARGER.
70 eurotuner aug
“I
t’s the only car I’ve been driving since
’04,” began John Betz, owner of Bahn
Brenner Motorsport (BBM). “I beat
the crap out of it, yet still it runs every
time flawlessly!”
For over three years, John has driven his
’96 GTI daily to work in Bend, OR. Under the
hood rests a 2.0 8v motor with a base of 115hp
and 135 lb/ft. But the engine is far from factory
stock. It’s equipped with BBM’s latest stage 3
supercharger kit, which has been dynoed at
216whp and 223wtq.
With its power-to-weight ratio, the 2600 lb
GTI is said to be capable of running down
many of today’s performance cars, including the
BMW 3-Series, Nissan 350Z and Subaru STI.
BBM offers three stages for its supercharger
kits, which are as easy to manage as they are
effective, as John has demonstrated with his
GTI. “These are real world kits that somebody
can drive on a daily basis. It incorporates
power, mileage and reliability.” He stated.
“If you look at cost-to-performance, you’re
going to have performance rivaling $30k cars.”
eurotuner aug 71
1996 VW GTI
Supercharger Selection
There’s no denying the 2.0 8v is weak in stock
form. The best way to gain more power is
forced induction, with either a turbocharger or
supercharger. During BBM’s research, they felt
a supercharger was better suited because of
the immediate torque value.
John revealed some of his experiences with
his stage 3 GTI. “At 2000rpm, the torque hits
200wtq. That’s when most turbos start to spool
and make roughly 150wtq,” he explained.
“Supercharged 8v are ideal because the engine
isn’t super high-revving, but is good for torque.
So when you combine a charger with the
engine, it’s a nice match that raises the
naturally-aspirated style power curve.”
Before developing the product, BBM
experimented with several different blowers in
search for the ideal combination of off-idle
torque and top-end power.
It’s generally considered there are three
types of superchargers: roots, centrifugal and
twin-screw. The centrifugal blower is similar to
a turbo, in the sense that as rpm rises, so does
the boost. Although all blowers are typically
rpm-dependent, centrifugal chargers produce
max boost at the top of the rev range.
This design is essentially a turbo driven off
“Supercharged 8v are ideal because the engine
isn’t super high-revving, but is good for torque.”
Power Stages
(right) From a
stock 115hp and
135 lb/ft to
216whp and
223wtq, thanks
to BBM stage 3
supercharger,
Techtonics
header and
exhaust, Mk4
intake manifold
and larger
injectors
(left)
The Lysholm
twin-screw
supercharger
fits snugly
Do you
remember?
John Betz and BBM are no strangers
to et. You might remember his
race-built, supercharged, six-speed
’90 Corrado 20v from et 1/04.
It competed in etGP two years in a
row, generating impressive power
thanks to its Lysholm supercharger.
Memorably, it put down 317hp and
252 lb/ft, making it one of the most
powerful Rados we’d seen to date.
We look forward to see what they
bring to etGP07.
72
the crank pulley, so they suit a high-spinning
motor with a rev ceiling that can maximize the
blower’s efficiency. However, the 8v doesn’t rev
high enough to produce significant boost.
At the other end of the spectrum are roots
and twin-screw chargers, often referred to as
positive displacement blowers for their ability to
increase power from idle to redline. Unlike the
centrifugal units, these maintain boost from
bottom to top, creating the effect of driving a
vehicle with a larger displacement motor.
The internal design of these chargers
consists of two counter-rotating rotors which
form a helix-shape. As the screws turn with the
crankshaft, air is pulled from the intake towards
the exhaust. It then is compressed by the rotors
and accelerated to create boost and power.
The problem with the roots blower is it
creates heat after 10-12psi. Although the
charger is making more boost, the heat can
negate gains.
With the right set up, both centrifugal and
roots units can make considerable power, but
BBM opted for the twin-screw. This design has
greater internal tolerances, making it more
efficient. The clearance between the screws is
basically the width of two human hairs,
allowing instantaneous boost and less waste,
continuing to build boost up to 20psi.
Mk3 2.0 8v owners aren’t expected to throw a
great deal of money at the car, since the book
value is around $3-5k. However, the BBM
supercharger kit means Mk3 owners can have
the power of a car that costs three times more.
Stage 1 – This non-intercooled kit costs
$2899 and includes all the installation
hardware as well as 22# injectors and BBM
software. The kit produces 8-10psi and provides
a little over 150whp.
Stage 2- Costing $549 extra, power rises to
over 180whp thanks to a 268/260° cam, 9.5:1
low compression head gasket spacer and head
bolt set. The upgrade also includes a smaller
63mm pulley compared to stage 1’s 73mm,
raising boost to 12psi.
Stage 3 – Costs a total of $4647, including a
front-mount intercooler, new software and a
55mm pulley capable of over 15psi. This gives a
reliable 215whp, taking the two.slow far from
its stock base output. Torque is also notably
higher, with the dyno exceeding 220wtq.
The kits fit any Mk3 2.0 8v including the
Golf, Jetta, Cabrio and Passat. “We spent
countless hours on the dyno refining and
testing the kit, especially the software,”
explained John. “It’s now like OEM. You can
even maintain your gas mileage if you’re not
using the horsepower on the freeway because
we use a bypass valve. Yet power is on tap
whenever you need it.”
One of the benefits of BBM’s supercharger
is that it’s oil-fed. It draws fuel from the oil filter
housing and returns it to the pan after first
greasing the helical-cut gears. This increases
supercharger longevity, allowing the bearings
and gears to be properly lubricated.
TECH SPEC
1996 VW GTI
Owner: John Betz
Location: Bend, OR
Occupation: Owner,
Bahn Brenner Motorsport
ENGINE:
two liter ABA 8v with
BBM stage 3 supercharger kit,
software, 268/260° cam,
billet fuel rail and FPR adaptor,
FMIC and 3" billet MAF housing,
Techtonics Tuning race header
and 2.5" exhaust with Borla
muffler, Mk4 intake manifold,
440cc injectors
DRIVETRAIN: five-speed
manual 020 transmission with
Peloquin LSD, ACT four-puck clutch
with BBM lightened flywheel
SUSPENSION: H&R coilovers,
polyurethane bushings, front
and rear sway bars
BRAKES: Girling 60 two-piston
calipers with drilled and slotted
rotors
WHEELS & TIRES: 15x7" Ronal
Racing Rallye three-piece
magnesium wheels, stud
conversion, 195/45-15 Kumho
Ecsta tires
CONTACT
Bahn Brenner Motorsport
541/388-1202,
www.bahnbrenner.com
EXTERIOR: Kerscher front
bumper, OE European textured
bumper top, fender flares and
side moldings, Votex long fogs,
Hella Mk4-look headlights,
color-matched rear valance,
BBM exhaust tip, M3-look tail
lights, carbon fiber hood, JOM
badgeless grille
INTERIOR: Auto Meter boost
gauge, BBM shift knob
AUDIO/VISUAL: Nakamichi
head unit, JL Audio 10" W7
subwoofer, Focal speakers
THANKS: Jeff Atwood at
C2 Motorsports
Rare 15x7" three-piece Ronal Racing Rallye magnesium wheels,
sourced from VW Motorsport’s American race team
eurotuner aug 73