20 How can I get more power out my VW?
Description
This article is from the VW Performance FAQ, by with numerous contributions by Jan Vandenbrande others.
20 How can I get more power out my VW?
A:Buy a VW with a VR6 engine :->. It's an FAQ that's worthy
of a book, and that's probably where you should start.
After you go through this FAQ to give you some general
idea, look at the info archive under power upgrades:
http://www.cis.ohio-
state.edu/hypertext/faq/usenet/autos/vw/performance-
faq/faq.html
The actual archives are mirrored at a variety of
locations also mentioned in that FAQ.
Following are a couple of old known modification which are
easy & relatively inexpensive that will increase the power
of the car. In general, the older the car the more room for
improvement. Newer VWs have much less room for easy
improvements because many of the components are already
near optimal.
One easy upgrade path for older VWs is therefore to look at
newer VW (Audi) models, see what they did, and see if you
can swap parts. For example, older VWs have the restrictive
exhaust systems, swapping it with a large diameter one from
a newer model (if possible) or using the catalytic converter
from an SLC will help.
Also be aware when buying "performance" components on their
true benefit. Usually the top horse power gain is quoted
while ignoring the rest of the power band. Your car may
have more top end (high RPMs) while sacrificing power at the
low end (low rpms) which is where most street driving
occurs. The over all effect may therefore be that the car
may actually feel slower off the line, but be great when
passing another car.
So first decide where you want to improve, then research
whether the component in question really achieves that. Also
select performance parts that fit in the stock position over
those that do not. This is probably more true for suspension
components than engine components, but is a good general
rule to follow. Parts that deviate too much may require
extensive modifications, sacrifice reliability, make more
noise, or may even render you car unsafe.
In general: Reduce the exhaust backpressure (performance
exhaust) Advance the timing (recurved distributors,
chips...) Improve breathability (K&N Filter, head port,
throttle body, compressor) Add a hotter cam Enlarge the
engine (change head, pistons, crank) Replace the engine with
a more powerful one.
All cars: Use a K&N Filtercharger air filter element (some
will argue whether this makes any difference). High end
improves a bit. Corrados: 3 HP gain at top. Replacing the
airbox with a filter at the end of the air intake also
provides some additional gain (but you'll also hear more
engine noise...).
Use synthetic oils (motor and transmission).
83-84 GTI:
Change throttle body with a bigger one (Audi?).
[From Peter Tong]: You can get one from a later Audi 5000
of the aerodynamic body style. I think 82 and up.
Another good donor car is the '85 Golf or a Golf that had
CIS-lambda. You have to seal/cap off a vacuum line
coming off it, and in almost all cases transfer your
throttle linkage from your '84 TB to the new TB. Just
make sure that the newer throttle body has a screw
adjustment for the idle speed. You also want to purchase
a really small l screw driver/flat bladed screwdriver bit
to adjust the idle. On the 84s the idle adjustment was a
hex that was easily adjusted on the newer TBs its a screw
and with the TB mounted on your current manifold its
harder to adjust the idle. You also want to make a plate
to put between the new TB and your old manifold to smooth
airflow (your 84 manifold has a TB opening that doesn't
match the newer larger TB). Buy an old style TB gasket,
and a newer style gasket, perhaps new 6mm allen bucket
bolts to attach it, and make the plate to go between it.
If you want a plate cheap just send me $5 and I'll send
you my old one (I had my intake manifold ported and the
opening opened up).
BTW, even with a Fox manifold the TB is good for at most
4hp.
84-87 Scirocco (US):
For the JH 1.8 big-valve engine, use a dual-outlet
exhaust manifold from any early car up to '81, get the
short TT's downpipe (retain cat) for 10 HP, with a 17%
gain at 4200 rpm and more torque Optionally: replace
exhaust system from the cat back (US$150) & factory VW g-
grind camshaft (Autotech, $99)
[From Peter Tong]: What is the difference between the TT
downpipe and the downpipe that come stock with the dual
outlet manifold on earlier cars?
The length is different. The diameter is smaller. The
bends are slightly more abrupt in most cases (some
aftermarket replacement downpipes aren't mandrel bent
even with inner side radius' slightly pinched in). On
most of the earlier cars with cats the stock downpipes
mated before the cat with a flexpipe. The flexpipe
doesn't hurt flow much but is of smaller diameter. Also
the position of the collector on the stock pipe is such
that it would help at higher rpm - the problem is the dp
diameter is too small to support the flow at that rpm
(this is from my experience). In the end count on the
stock dp getting really restrictive around 115hp. When I
first put my 2.0 in and was really revving it - the back
pressure from the stock dp combo was so much that I blew
a nickel sized hole it it! This happened even though I
was running a 2" exhaust and supertrapp rear of the cat.
Kind of funny but it happened to seak out the weakest pt
on my stock dp and took it out. The stock dps also
have two welding methods that I've seen holding the
exhaust manifold flange mating surface. One uses a small
metal "brace" the other type is just welded to the pipe.
The TT downpipe is nicely made and has worked well on my
car. It is stiff in many ways compared with the stock
system, and tends to transmit more vibrations than the
stock system (perhaps due to the stiffness). The
collector joins about 2.5-3" before the cat and is 2"
diameter pipe. Tubing is mandrel bent and the angles
aren't quite as severe as on the stock dp. Also you
eliminate the flexpipe with the TT cat dp. What did it
do? When I installed it - the midrange really improved.
Top end also to a lesser degree.
As for actual #s for what they did on my car:
40-60 in 3rd gear: 4.6s before and 4.3 after. This
tests 3k to 4.5k rpm.
50-70 in 4th gear: 7.9s before and 7.5 after. 3rd
is 1.29 and 4th is .91.
r&p is 3.89.
So you can see it improved the midrange by about a 6%
average. Is it worth $115? It is I guess - it depends on
if you are a geek like I am at trying to extract as much
out of your engine as possible. As it is that pipe, the
G-grind and the TT adjust cam sprocket are the only
aftermarket items that were necessary for me to purchase.
Oh BTW, fuel economy should improve slightly as well.
Fox:
Remove exhaust restrictor (see also further and EuroCar:
April 89, Aug. 89, Dec. 89, Apr. 90, Aug. 90)
90-92 Passat (4 Cyl):
Remove air-intake restrictor, APS Chip, cam. APS chip for
automatics that is supposed to do wonders for low end and
shift points. Applicable to all cars with 9A engine (inc.
16V GLI).
85-92 8VGolfs/Jettas:
The biggest gain can be had with a better down pipe and
exhaust system.
85 GTI:
Change ignition map by cutting wire #11?? on the ignition
control unit and grounding #3 (which was connected to
#11). Yields 2 HP additional, torque peak occurring at a
lower rpm. See also 85-87 GTI for additional power.
85-87 GTI: KE-Jetronics:
Advance ignition idle timing to 12 degrees BTDC or until
knock. (factory specifies 6 degrees +/- 2). Gains 5-8 HP
with >= 92 octane fuel, very noticeable at the low end.
Note, it may reduce the life of your catalytic converter.
90-92 16V GTI/GLI:
Motronic Power chips from Autothority & APS.
Corrado G60:
Stage 1, 2 & 3 chips/packages from APS & Autothority (&
others).
Stage 1/P-Chip: Chip swap, improves low end by torque
18%, high end by ~5%. Gas consumption
improves but you do need Super Unleaded. One of
the BEST improvements you can make to this car.
Stage 2: Pulley change, chip & fuel pressur regulator
(AT) or exhaust (APS) => Power boosted to 180 (APS)
or 200 (AT).
Noisy, too powerful for the car, APS is more
drivable,
AT's not CARB approved. Gas consumption near stock.
Stage 3: Like Stage 2 but with a cam, affects mostly high
end.
Remove cold air snorkel (too restrictive) => 1-2 HP gain
at the top end (Note: WAY too noisy).
Use Neuspeeds Generation 2 system. It solves the airleak
created by the idle stabilizer valve. This mod
seems to work with most of the above mods as well
and provides better boost under all conditions.
See also archive G60_Power_Upgrades and Air_Intake_Mods.
VR6 2.8l & 2.9l Models (Corrado SLC/VR6, Passat GLX, Golf
III, Jetta/Vento):
Power chips available from both APS & AutoThority &
others.
Stage I/P-chip: Gain of 7-10 HP at the top end. Most
people reported little or no gain. Some have
complained that AT's chip seems to produce knock.
Replace throttle body w/o internal air ramp (10% more
airflow). This is nothing more than the European
progressive TBody. It does make the low end a tad
weaker, which, combined with other enhancements
will make the car less jumpy.
K&N P-Flow filter. APS recommends the above 3 combined to
produce the best effect to produce an additional
30 HP.
Remove cold air snorkels (too restrictive). Their
technical name is "Helmholtz resonator", and it's
indeed a sort of muffler.
Get a new set of cams, such as those from Schrick. Note:
Mostly improves the top end.
Use VW Motorsport's Variable Inlet Manifold (VSR). See
archive on this. An alleged gain of 30-50 HP at
3000 rpm! Expensive (2300US$), but chances are that
certain shops may produce a low cost immitation.
Buy a turbo charger kit. VW is about to release a Van
called the Sharan that uses a 250Bhp Turbo VR6.
Other turbos on the Vr6 have produced around 300Bhp
making the car virtually unmanagable.
There are a few 3.1 liter conversions available. Not
enough info on that as yet.
>>>Probably LOTS MORE...
Caveat: Most of the above are merely small fixes that do not
require replacement of a major engine component such as the
cam or the exhaust system, which is usually the next step
towards major engine improvements. Those enhancements
require a lot more work and expertise to install.
Caveat II: Most of the above improvements are approved by
the air resource boards for street legal use, but some are
not (Stage II, Corrado). Before you install any equipment,
make sure that you understand the full implications.
Tampering with pollution control equipment is a serious
crime, punishable with a 20 000 US$ fine in many states of
the USA.
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