Supercharged with Silicon

The Dawn of the Digital Hot Rod! 

By Barry Winfield 


As six hot cars career along the Firestone test track at Fort
Stockton, Texas, competition and apprehension reign among one group of
spectators: the guys who, to the tune of more than a half a million
dollars, have tweaked these cars into terrifying shape. Taken
together, these six monsters produce 2,400 horsepower - enough to run
a fleet of stock Toyotas or Fords. A Corvette modified by drag racer
John Lingenfelter scarfs up the long, banked track at 189 mph. Race
driver Peter Farrell's dangerously red Mazda RX-7 has been pumped up
from the stock 255 horsepower to a mind-boggling 360. A transmogrified
BMW 850 boasts a V-12 engine that now belts out 475 horsepower. A
flag-yellow Mercedes-Benz 500SL - upgraded by RENNtech of Delray
Beach, Florida - struts its US$200,000 stuff, running out of revs
before it runs out of power: It screams off at 182 mph and 6,200 rpm. 

The aim here, obviously, is to go as fast as physics will allow. In
the not-too-distant past, cars were hot-rodded exclusively by the
addition of larger carburetors, free-flowing exhausts,
high-compression pistons, wider camshafts, or big bore jobs. Some of
these techniques are still in use, but any engine modification these
days also requires new engine-computer chip strategies to manage the
revised operating parameters. The revolution in automotive electronics
has spawned an $80 million industry supporting more than a dozen
aftermarket chip companies. 

Thus, with the BMW 850, the original engine's computer chip was
ditched. With it went the 155-mph automatic speed limiter that many
current German and Japanese manufacturers have adopted. In keeping
with the car's brutal new persona, the replacement chip promises a
much less sanctimonious attitude. 

The car's tuners - from a company called AutoThority - have already
run the car faster than 155 mph, and they are confident that their
various tweaks will see it clocking top speeds in the 190-mph range on
the Texas circle track. As the car pulls out, a ripple of interest
runs through the assembled participants. But then, to our collective
surprise, after streaking eagerly to 170 mph, the car hangs there as
if held back by an invisible rein. It turns out that the BMW, which
sports an all-electronic fly-by-wire throttle system instead of the
mechanical linkage most cars use, has two speed limiters. The first
one is in the engine-control module chip, the second - at a slightly
higher speed - is in the throttle-control circuitry. The guys from
AutoThority are mortified. 

Such are the pitfalls facing aftermarket car-computer hackers, those
guys in the arcane business of recalibrating the chips in car engines
to defy the original intentions of their makers. 

Now, car manufacturers are not by nature killjoys, but among the
factors they must consider when setting up the many values that
control the function and performance of an engine are drivability (the
smoothness, response, and predictability of a car), durability
(manufacturers have to stand by their products for many years and many
thousands of miles), and, of course, exhaust emissions (the car has to
meet federal or state tailpipe regulations, for a specified period of
time, under warranty). 

Some owners are less preoccupied with these considerations than they
are with power and speed. These people give performance a higher
priority than durability. And, until recently, many of them neglected
tailpipe emissions altogether. But that's not an attitude the
aftermarket chip industry can afford these days. Thanks to aggressive
policing by the Environmental Protection Agency (EPA) and by the
California Air Resources Board (CARB) (much of the car chip
aftermarket is, predictably, in California), aftermarket automotive
companies have to be sure - dead sure - that they do not degrade the
exhaust quality of a car they modify. The penalties are dire, with
hefty fines levied for each car modified. A few year's worth of
vehicles on the wrong side of the law, and you're as good as broke.
And manufacturers will void vehicle warranties if aftermarket
modifications cause cars to fail legal emissions requirements. 

Not to exaggerate the problem. Tailpipe emissions tests run by the EPA
and CARB - though differing in some details - are programs run on a
dynamometer to simulate a cold start followed by an urban driving
cycle with periods of idling, as if the car were caught in traffic.
Prolonged wide-open-throttle bursts are not tested. So some makers of
aftermarket engine-control chips focus on the top end, leaving the
original manufacturers' calibrations much as they were at start-up,
idle, and part-throttle settings. 

Full throttle at high engine revolutions often gives the big gains
anyway. According to Blake Carpenter, chief engineer at Texas-based
Hypertech, many production cars run quite rich (a high fuel-to-air
ratio) at full throttle, with less spark advance than is optimal for
maximum power. This is typical manufacturer conservatism. With that
cautious strategy, the car makers are dealing with possible fuel
quality fluctuations. The event they fear most is detonation, produced
by too low an octane rating, too lean a mixture, too advanced an
ignition spark, or a cozy combination of the lot. 

(Detonation is that "pinging" or "run-on" that plagues old cars when
the ignition is turned off. It occurs when the compressed fuel-air
mixture explodes spontaneously in the combustion chamber instead of
burning evenly across a rapidly moving flame front. If the conditions
are right, detonation - or pre-ignition as it's also known - does not
even require a spark from the ignition system; red-hot carbon deposits
or engine parts will do. However it occurs, it's bad news, eventually
leading to serious engine damage and poor performance.) 

From the chip hackers' standpoint, the manufacturers' cautious
approach to full-throttle calibrations leaves them some leeway. At the
right levels, lean mixtures and lots of spark mean better performance.
And that's where Blake Carpenter looks for it. He says many cars
per-form better with more spark advance and leaner mixtures. Except,
that is, for the serious performance cars. Cars like Corvettes and
Camaros, he says, are calibrated close to the edge at full throttle.
Their designers control detonation problems with piezoelectric knock
sensors, which hear the onset of detonation, then instruct the
computer to retard the ignition. 

The new Corvette LT1 engine, says Carpenter, proved a real challenge:
Only after a year of research could any improvements be found. Nothing
in the spark and injector values was worth going after. Lots of work
on what's called reverse engineering (analyzing the original equipment
values) and plenty of data from fifth-wheel equipment (precision
speed-measurement equipment using either calibrated wheels or an
optical device attached to the car) led him to the electronically
controlled coolant thermostat. It was opening at fairly high
temperatures, to speed warm-up in colder climates for better heater
and emissions performance. Carpenter punched in a new, cooler value
(160 degrees versus the 175-degree stock setting), and the car
responded with more power. The LT1, he says, likes cool cylinder-head
temperatures. 

This protracted investigation starkly contrasts with the routine for
tamer vehicles. A 1989 Chevy Lumina Eurosport with a 3.1-liter V-6
engine had so many spark and mixture settings that the car was easily
transformed. In fact, says Carpenter, the new calibrations not only
boosted acceleration - shaving off about 1.2 seconds from standstill
to 60 mph - but also took a surprise toll on Hypertech owner Mark
Heffington: During an in-car demonstration, the fifth-wheel display
unit leapt off the dashboard and smacked him in the face, chipping a
tooth. 

After all that, adds a rueful Carpenter, only about two chips sold for
that car all year. Clearly, the Lumina is not the car
performance-oriented customers snap up. Carpenter says manufacturers
seldom tune for optimum power, preferring to tune for 87 octane fuel
and emissions performance. By changing only the wide-open-throttle
strategies, it's relatively easy for Hypertech to meet EPA and CARB
certification requirements. They submit chip files to show what
they're doing to the chip and usually get an immediate exemption order
that allows them to sell the product. Occasionally, however, they are
asked to run tests with the new chip. 

Ignition and fuel strategies are only two ways to heighten
performance. Modern engine control units also guide transmission
function, setting shift points and locking or unlocking torque
converters at predetermined points. Veteran engine computer hacker
John Adrain, of Adaptive Technologies, says he remembers an Infiniti
Q45 with a chip from Jim Wolf Racing that picked up 1 1/2 seconds
between 60 and 80 mph by simply moving the transmission shift points
400 rpm up the dial. 

Adrain would know about engine control: He invented and markets the
Prompaq, a device that mounts four separate engine control PROM chips
and patches into the car's computer. Any one of the chips can be
engaged by a simple key switch; it loosely resembles the
task-switching software on the computer this is being written on. The
Prompaq is the ultimate car-tuner's toy, enabling a driver to select
from various performance programs, depending on the application. Say
you want a towing strategy that pushes gearshift points up, even on a
light throttle, and stays rich and retarded for good cooling: Switch
to Position One. Want total acceleration to dust off that pesky Camaro
driver? Select Two. Handing over the car to a hyperactive valet?
Switch to the chip with the 3,000-rpm cutoff point and pocket the key.
Or, after parking, switch to the security chip that disables the
engine. Then walk away. 

Of course, Prompaq is great for aftermarket chip developers. It's an
easy way to compare various configurations in back-to-back tests
without carting around a laptop loaded with engine settings. But
Adrain is already moving on. He has filed a patent application for a
novel computer piggyback system that lends much greater flexibility to
an original equipment engine-control computer. He believes that
there's a real need for continual recalibration of car computers. "For
one thing," he says, "the fuel formulas keep changing." 

AutoThority's Paul Misencik doesn't completely agree, but he concedes
that fuel quality varies quite a bit across the United States.
AutoThority's approach to the chip business (concentrating mainly on
Porsches and BMWs) varies from that of a company like Hypertech mostly
in that it works hard to improve drivability and throttle response
across the operating spectrum. It wants to make the car more fun to
drive. "The wide-open throttle work," says Misencik, "is a small part
of our operation." 

Remapping all of an engine's operating values demands more than just
tightening up the wide-open throttle parameters. Reverse engineering
is so complex as to stump the pros. "Dump out the data on a chip,"
explains Misencik, "and it comes out in hexadecimal code. It looks
like gibberish. So it's difficult to see which maps are which." 

Maps are sets of values arranged in two- or three-dimensional grids.
One axis may be the throttle position, another the speed of the engine
at that time. The computer looks at the coordinates of these maps for
data points that initiate appropriate responses. AutoThority designed
graphic tuning software that allows it to identify maps and depict the
various engine-operating curves on chips its technicians have never
seen before. This saves days of reverse engineering. Misencik has
found that data points are often not laid out for optimum smoothness
and can easily be improved. The computer averages values between data
points when the coordinates do not exactly correlate, so the addition
of extra data points helps improve engine response and smoothness. 

AutoThority may be up to speed here, but Misencik points out that as
automotive technology advances, the opportunities for aftermarket work
decline. Right now the company profits from the tuning habits
characteristic of specific market areas. The Germans, says Misencik,
almost universally tune for slow initial throttle response (for smooth
driving in traffic) by maintaining relatively low levels of spark
advance. All the good stuff - suitable for high-speed autobahnstorming
- happens at higher revs during the deep part of the pedal's travel.
By contrast, the Japanese usually go for bright initial throttle
response. Case in point: the latest Mazda RX7 Turbo. "It kicks you in
the butt at the first touch of the pedal," he says. 

"We try to impart that eager feeling at part-throttle that Porsches
and BMWs normally don't exhibit. And we spend far more development
time on transitions, throttle response, smoothness, and crispness than
on full-throttle work. In fact, we knock the full-throttle stuff off
in a day. Because of this approach, it's harder for us to get
emissions certification, and it's more time-consuming and expensive to
do." 

He's not kidding. The application and test procedures (using a
dynamometer at an environmental research laboratory) cost the company
about $4,000, not counting its own development time. That's why
high-end chips can cost as much as $600 per set, compared with the
hundred bucks or so asked for the cheap and cheerful variety. And
although your average driver spends only 3 to 5 percent of the time at
full throttle, this full-spectrum recalibration is harder to sell to
the public. 

But AutoThority's modus operandi suits the upscale German car market
that makes up its primary business. Aside from the extra cost, it
seems the right way to go. If you're going to delve into the guts of
the beast, you might as well do the whole thing the way you want it. 

The possibility of this kind of aftermarket intervention may signal
just a brief interregnum in the course of automotive electronic
evolution. It's ironic: When cars first went electronic, the public
imagined the demise of end-user tinkering. We soon discovered that the
new electronic architecture could be figured out and modified. But
it's possible that accelerating technological innovation, combined
with steadily tightening government regulations, may soon result in
nonadjustable electronic controls on cars. Or will that just be the
ultimate hot rod/hacker's challenge? 

Adaptive Technologies: +1 (805) 488 8832. 

AutoThority Performance Engineering: +1 (703) 323 0919. 

Hypertech: +1 (901) 382 8888. 

Jim Wolf Racing: +1 (619) 472 0680.



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Last Modified: 04:54:21 AM - May 24, 1994 PST 
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