My 1999 540iA Sport is plenty fast, but nothing's perfect. Shortly
after I took delivery of it in February 1999, I called Dinan
BMW to inquire into the availability of performance modifications.
Because the 1999 engine and Steptronic transmission were new to the
US in the 1999 model year, they didn't have anything ready to go, but
they sent me a catalog of their suspension kits and other products,
and promised to call me when their performance products were ready.
I bought a G-TECH/Pro accelerometer
for use with my previous car, a 1992 Nissan Maxima SE. I could get 060
times in the low seven-second range, which is nothing to brag about
but nothing to be ashamed of either.
My very first attempt with the 540 gave me a 0-60 time of about 5.9
seconds. Careful experimentation eventually taught me how to get times
just under 5.5 seconds. If everything went right, I got 5.48 or 5.49
seconds. (I got a 5.25 once, but it didn't seem like a particularly
good run, so I assume that was a glitch.)
One of my goals in buying the car was to get something capable of 060
in under six seconds. Since BMW's official claim for the car is 6.1,
and car-magazine tests of the same car with the conventional automatic
transmission showed even higher numbers, I expected I'd need to do performance
work to get a five-point-something result. Getting under 5.5 with an
unmodified car was just wonderful.
But heck, I knew it could get faster. Everything can. As they say,
"How fast do you want to go? How much money do you have?"
In April, I got that long-awaited call from Dinan. It was Steve Dinan
himself, in fact, but he wasn't calling to let me know I could bring
in my car to get the mods installed. No, they wanted to know if I would
loan them my car so they could develop the mods! Dinan planned
three performance enhancements for this car: their popular engine-computer
"chip" (two versions, actually), a separate chip for the Steptronic
transmission, and a shroud to bring cold air from the front grille to
the air intake. Each of these makes the car a little faster; even together,
there's no dramatic improvement, but they're all cost-effective improvements.
At this writing, the engine software and cold-air intake are $499 each
while the tranny software is $299; all require some labor to install,
so the whole package would run nearly $2,000. (Check Dinan's Web site
In exchange for loaning them my car, I'd get the mods at no additional
cost. In effect, instead of paying cash to make my car faster, I'd just
have to do without it for a while and drive a rental instead. (Dinan
paid for the rentals, of course, and there are some stories to tell
about those... but back to the story at hand.)
My car was at Dinan for a couple of weeks, and when it came back it
was already noticeably improved in some respects. Dinan had installed
new software for the engine and transmission, but the parts for the
cold-air intake had not yet arrived so they gave me back the car while
we waited. The transmission shift speed and throttle response were definitely
improved and it felt stronger at higher speeds. The following graph
(a 616x486-pixel image; click to open in a separate window at full size)
shows the reported performance after this first set of work. There are
clear improvements in high-end RPM and time-to-speed, but the graph
also shows a problem: the 0-60 time is something over 6.0 seconds!
Figure 1. Graph of 0-100 performance:
RPM and speed vs. time.
This wasn't just a problem with their testing; the
car really was slower. As you can see from the slow takeoff (0-5 mph in
slightly over one second) the problem was with the initial launch. I spoke
with Dinan about this problem, and they agreed to take a look at it when
they took the car back for the cold-air intake.The car went back
a few weeks later, and Dinan confirmed the problem was present and was
not related to their software changes. They took the car to a local dealer's
service shop, which determined that the transmission torque converter
had failed. After that part was replaced (under warranty) and the new
cold-air intake was installed, Dinan performed a few more tests on the
car and returned it to me.
One more graph shows the final results in terms of horsepower and torque.
Dinan estimates the new maximum engine horsepower at 302 based on the
factory number of 282 HP. The new torque peak is shown as 338 lb-ft,
vs. the factory claim of 324 lb-ft.
(Yet to be scanned; patience please!)
Figure 2. Graph of engine horsepower
and torque vs. RPM.
I've been accumulating additional runs with my G-TECH/Pro, and I'm
getting reliable 0-60 times of about 5.35 seconds, and I've even seen
a few 5.30-second readings. This isn't a huge improvement, but it's
more than merely statistically significant. I wish I'd had a chance
to get quarter-mile times before the mods, but the car is said to be
capable of reaching 105 mph in a quarter mile even in factory trim,
and it just wouldn't be safe to run tests like that except on a track.
With any luck I'll get a chance to try quarter-mile runs on a track
in the next year. I'll be sure to report my results here.
Note that Jim Conforti is also working on a new performance chip for
the E39; keep an eye on his company's Web site, Bonneville
Motor Werks, for more information.