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Building a Reliable and
Powerful Street Engine
by Jim Ratto
Over
the last decade or so (or, at the very least, since 1995) the Volkswagen
sub-culture has relished the re-birth of the once popular, so-called California
Look style. The traditional style was created within Southern California during
the late Sixties and early Seventies. The band of enthusiasts within this inner
circle were striving to assimilate street-legal Volkswagens that were
kissing-cousins of their drag-race siblings such as the famous Inch Pincher and
Dynosoar gasser sedans of the era. The effect these young zealots had upon the
VW scene was phenomenal. The result was a style that not only improved the
appearance of the Beetle, but also its abilities on the street and strip.
By 1972 or so, numerous VW's in the Southern California area had adopted the
latest style, which included a lack of bumpers and exterior moldings, a lowered
front suspension (and a resultant "raked" stance), lightweight alloy wheels and
in most cases, a modified and highly tuned engine. While the exterior changes
were somewhat subtle, the engine modifications did not go unnoticed. Typically,
many of the California Look VW's roaring around Los Angeles were powered by
1700cc or larger, dual-Weber-carbureted engines, some as large as 2000cc or
more, making such VW's blindingly fast. Pioneers of the VW street-scene such as
Doug Gordon and Don Crane were regulars at Southern California dragstrips,
consistently posting quarter-mile times of 14 seconds or less. Yes, way back
when.
Fortunately the contemporary resurrection of the traditional California Look not
only honors the established key appearance transformations, but also outright
performance without compromise. Indeed, a "genuine" California Look VW is
defined by its high-output engine. It is now quite common to find a street VW
with as much as 210 horsepower. Even VW's utilized for frequent street use can
enjoy the merits of a 2000cc-plus, high-output engine (in the region of 150-160
horsepower), if planned and assembled correctly. Attention to details counts
here, more so than you may think, as does defining your goal, and keeping this
goal in sight. As the planning, machine-work and assembly-work transpires, you
must stick to your initial goal, as this will ensure that all the parts you
select will coexist and operate "together", as a fluid-like package, producing
profuse amounts of horsepower and torque, but remaining completely reliable
while doing so.
The first factor to deal with is the total cost of the project. Be honest and up
front with yourself. Building a reliable, yet powerful Volkswagen engine takes
dedication and a firm financial commitment. The costs can add up fast, and to
search for "the best price" isn't always the key to success. Parts that produce
streetable horsepower never come cheap. To take shortcuts is to design premature
failure into the entire engine system. For example, an individual can select the
wildest cam-grind offered by a camshaft manufacturer, but without the proper
valvetrain, connecting-rods, cylinder-heads, intake and exhaust-systems and
gearing (among other aspects of both the car and engine together), the results
may prove highly disappointing, if not disastrous! The key here is to evaluate
your budget, and use these figures to guide your search for suitable parts.
The next prime consideration to be evaluated during this planning stage is the
first and foremost use you will have for this engine once it is completed. An
all-out drag-racing engine is definitely not the same as a daily commuter engine
(though there are probably a number of VW enthusiasts who'd like to argue with
me here!) Even a "weekend warrior" type of project is far from being suitable
for a daily driver. I feel that it isn't feasible to expect an engine that was
created with top-quarter mile E.T.'s to spend its life drudging back and forth
in highway traffic.
Obviously, if all-out horsepower is your goal, you will follow a very tried and
trued path in gaining it, using very radical cylinder heads, a long-overlap cam,
large carburetors and also a hefty price tag. However, if you plan to drive your
California Look VW every day, you'd be wise to select cylinder heads that
provide good mid-range torque over ultimate-rpm horsepower, along with a more
conservative camshaft and carburetors. Don't be misled though, a reliable,
high-output engine can be built, and be built with fairly regular use in mind.
Not exactly daily use, but more than just the occasional weekend outing as well!
This brings us to the next important factor to plan: the displacement. If
economically feasible, you should plan on building the largest displacement
engine you can afford (note the words "you can afford.") I feel it is much more
wise to build a larger displacement engine that makes its power and torque
through its sheer size, rather than a smaller engine that will require high
rpm's to generate decent horsepower (and typically more exotic heads and
valvetrain to attain higher rpm's). The larger displacement engine will
generally prove to be more enjoyable to drive, especially at times when it isn't
practical to see the high side of seven-grand. The next item in the lower end of
the engine to consider is the camshaft. The California Look crowd has always
held very strong views in the choice of camshafts for their street/strip
machines. Often, these street sedans will run a full-blooded race camshaft, and
do so quite successfully. It is quite common to find the serious contenders
erring on the wild side of the camshaft spectrum. A review of many 12 and 13
second VW's will find cams such as the Engle FK-87 or the Web Cam 86C, both very
radical grinds, that normally would run very poorly in a street sedan. Both of
these cams exceed 270 degrees of actual duration (measured at .050" cam lift),
and lift the valve over .550". In comparison, the popular Engle 110 "street" cam
measures 247 degrees actual duration and lifts the valves about .430". Yet, you
are unlikely to find the Engle 110 in a very high-output engine. Not that it
won't produce good driveable power, it just will not allow a large cc engine
(equipped with the right cylinder heads, intake system, exhaust system and
gearing) to wind to rpm's much over 5500 rpm.
So, are the owners of the 12-13-second VW sedans throwing driveability out the
window with their radical cam grinds and large cc engines? The answer is "no",
and there are reasons for this! First of all, most fast VW's run engine
displacements of 2000cc's or larger. This increased displacement generates much,
much more torque than a smaller engine (say a 1776, for example), and this
torque makes up for the loss of bottom-end torque that is usually associated
with radical valve timing. The effect of longer duration has even less effect on
low-end torque with cranks longer than 82mm! The reason is again, that the
longer stroke cranks increase piston speed, offsetting the effects of increased
valve timing.
Secondly, these very fast street cars utilize an intake system that provides a
separate throttle plate and intake port for each cylinder. By providing each
cylinder and intake valve with its own intake tract and throttle plate,
reversions caused by increased cam duration are isolated to each cylinder and
intake tract, allowing for smoother running. If these wild camshafts were used
with an intake system that shared a throttle plate for all four cylinders, the
engine would run very, very poorly. A very rough idle would result, as well as a
very "peaky" powerband, only making good power and torque at high rpm, if at
all. By isolating the pulsations and reversions within each intake runner, the
intake system can more dampen the effects of increased valve timing and overlap.
Another reason these radical cam grinds work well in so many all-out street cars
is due to their transaxle gearing. Most of these cars are primarily used for
drag strip action, and not surprisingly, the cars are geared super closely. The
reason for this is to keep the engine "on the cam" in between shifts. If stock
gear ratios were used by these very fast street cars, their engines would climb
the rpm range very slowly in the second gear to third gear shift and in the
third to fourth shift again, resulting in slower acceleration and decreased
performance. With close gear ratios, these engines fall in the rpm very slightly
between shifts, keeping the rpm's well within the cam's "sweet spot." Typically,
the wilder the cam, the closer the gear ratios will have to be. This is
something to not consider lightly, as close ratio gears will decrease your
street car's ability to be a "daily driver" (increased highway cruise rpm's will
result).
Hopefully, one can see how the successful choice of a camshaft will require
evaluating several factors. As mentioned before, the larger an engine's
displacement is, the more cam it can use. And knowing that added displacement
can be gained by different means (by increased bore-diameter, increased
stroke-length or a combination of both), different camshafts should be chosen,
even for engines of similar displacement. For example, a 1915cc engine can be
built using 94mm pistons and the stock 69mm crank. Assuming we are using
stock-length connecting rods, this engine will have the same piston speed as a
stock VW engine. For this engine, I would think twice before dropping a wild,
long-duration cam in. However, if a 1900cc engine were built by using a 74mm
crank and 90.5mm pistons, because of the increased stroke-length, this engine
would run better with a fairly hot cam. Of course, add 94mm pistons to this
combination, and you'd have a better running engine yet!
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