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Improving the über coupe
By Josh Jacquot , Senior Road Test Editor Email | Blog
Date posted: 02-05-2007
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Vishnu is a strange name for an automotive aftermarket company. In Hinduism, Vishnu is the god of preservation, responsible for maintaining balance in the universe — or, in this case, the balance in the BMW 335i.
Balance has become Vishnu's slogan. At Vishnu Performance Systems, tuning for ultimate power is less important than upgrades that deliver all-around drivability.
Moving into a new universe
Vishnu has made its name by selling engine-control upgrades for the Mitsubishi Lancer Evolution and Subaru WRX and WRX STI. But now company founder Shiv Pathak is looking upscale.
The BMW 335i is the perfect launching point.
Its 3.0-liter inline-6 engine delivers 300 horsepower right out of the box, and its two turbochargers mean there's lots of headroom to pack in more power.
Plus, the BMW 335i is fast.
As we learned in our full test, the 335i is substantially quicker than BMW's own claims. Our test car (a questionably tuned press vehicle) smoked to 60 mph in only 4.8 seconds and eclipsed the quarter-mile in 13.3 seconds at almost 106 mph.
This incendiary performance puts the cooking 335i in the same league as dedicated performance pieces like the Audi RS 4 and the Mitsubishi Evo IX — cars that don't come close to offering the Bimmer's stealth factor.
How it works
Vishnu's tuning philosophy is an example of clever engine management. And it's particularly effective with turbocharged cars like the 335i that are already carefully tuned by the factory to deliver measured doses of boost under the narrowly prescribed conditions determined by BMW's engineers.
Making more power means adding boost, then tweaking fuel delivery and ignition timing. Doing so effectively requires that the stock engine-control computer thinks all these parameters remain within the expected range set by the factory. Vishnu uses a combination of electrical and mechanical devices to keep the warning lights off, but manages to keep the factory-set failsafe measures in place.
The biggest tweak is a magic box called PROcede, which intercepts sensor signals in the 335i's wiring harness. It's designed specifically to operate with signals from BMW's high-resolution crankshaft sensor and allows Vishnu's Pathak to make more aggressive tuning changes than would be possible using lower-resolution electronics.
Mechanical changes are limited to careful rerouting of the boost control plumbing and the addition of a small pellet in one of the vacuum lines to control airflow. In conjunction with the electronic controls, these changes make more boost pressure possible without disabling any of BMW's measures to preserve engine durability.
Another bonus is a downloadable software package that allows users to connect a laptop computer to the 335i's ECU (just as a real tuning engineer does) and view digital gauges displaying boost, air/fuel ratio and ignition-timing data. The software also has data-logging capabilities and can produce horsepower figures based on a simulated dyno pull in 3rd gear. It can also calculate acceleration to 60 mph and through the quarter-mile.
Balance
The perfect combination of performance and comfort is what sells thousands of BMW 3 Series every month in the United States. Adding a little more performance without compromising comfort or durability is what Pathak set out to do with the 335i.
It works. A 100 pound-feet increase in torque over a stock 335i from 2,000-4,000 rpm makes the Vishnu 335i not only quicker but also immensely more drivable. It never falls out of the power band. Roll into the throttle from 80 mph in top gear and the improvement in acceleration is, at first, only "meaningful." It quickly builds to "substantial," reaching its zenith at "Holy crap, this thing means business!"
The sound this car makes is as impressive as its acceleration. The Vishnu 335i has been fitted with a prototype cat-back exhaust system that uses dual 2.5-inch, mandrel-bend stainless tubes and oval Magnaflow mufflers with polished 4-inch tips. The system retains the stock downpipes, which contain two catalytic converters each and the tips look utterly stock.
You can get intoxicated from the sound. Few engine notes are more pleasing than a straight-6 with a real dual exhaust. The Vishnu 335i makes a burbling ring that builds to a ripping shriek at redline. We found ourselves mashing the BMW's throttle just to hear it build.
The engine never sounds like it's working hard. Pulling from 2,000 rpm in 6th gear, the engine emits a low-pitched garble that slowly builds in intensity as boost rolls on. Once the engine reaches full boost at 2,500 rpm, the coupe rockets from 70-100 mph in 6th gear with little effort.
How's she run?
In an effort to preserve its stealthy appearance, Pathak has retained the 335i's stock wheels, tires and suspension. With a ton more engine torque than stock, we expected this combination would turn the coupe's 255/35R18 rear rubber into vaporized stench in no time. We were right.
Too much throttle easily cooks the tires and careful pedal work is required for an effective launch. Feed in the clutch at 3,000 rpm while carefully finding full throttle; you get some wheel hop off the line but a very quick launch.
Sixty mph arrives in 4.6 seconds and the quarter-mile flashes by in 13.0 seconds at 109 mph, 0.3 second quicker than the last stock 335i with an automatic transmission that we tested. And that's quicker than any stock Evo or Audi RS 4 we've ever tested.
Combine this acceleration with the 335i's potent braking (114 feet from 60 mph) and handling numbers (0.88 g on the skid pad, 68.4 mph through the slalom) and the Vishnu coupe is capable of beating all but the twistiest roads into submission.
This car also did a real number on the Dynojet chassis dyno at MD Automotive in Westminster, California. Peak wheel horsepower increased 75 hp from 265 hp to 340 hp over the privately owned BMW we tested in our first full test of the 335i coupe. But the real story here is the torque increase, which makes the 335i substantially more drivable than before. As we mentioned, the torque peaks at 390 lb-ft — 114 lb-ft more than stock. The margin decreases toward redline, although there's still a 50 lb-ft surplus.
The bottom line
During our test, the Vishnu 335i had 11,000 miles on the odometer, an indication of the substantial test mileage it had racked up in only about two months of development time. Vishnu currently has about 30 beta versions of the system in the hands of customers. Full production versions are available now for about $1,300.
Outright speed hasn't been the primary goal with the Vishnu 335i and it also isn't the primary accomplishment. The 0.3-second improvement in quarter-mile time over the stock 335i isn't as impressive as the torque-rich driving experience. It's hard to argue with almost 400 lb-ft of torque at the wheels for less than the cost of a decent set of wheels.
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