"Injection is nice, but I'd rather be blown." —old timey drag racer T-shirt saying. Blatant sexual reference aside, there's a lot of truth in that statement. Since the dawn of the internal combustion engine, those who tinkered with motors realized that getting more power out of an engine meant getting more air in, which brought about the birth of forced induction in all of its many forms. Neuspeed's new supercharger for 2.0L VW engines has its roots (Excuse the pun.—MAX) in almost 100 years of high-performance technology but with a definite 21st century spin (Yet another pun, sorry.—MAX).
Like many other automotive buzz-words, the term supercharging (Like its cousin, turbocharging.—MAX), gets used a lot, but not always in the right way. True, they are both bolt-on power-adders, but the principles behind them are very different. For that matter, there are different types of superchargers, and each has its pros and cons. If you're considering adding forced induction to your VW, you should understand the principles behind the process. Then we'll take a close look at what makes the Neuspeed supercharger tick.
Forced Induction Basics
A naturally aspirated engine—one devoid of a forced induction system—relies on atmospheric pressure to fill the cylinders with air during the combustion cycle's intake stroke (Okay, we understand that's a gross generalization, since it doesn't take into account the vacuum effect of the piston's downstroke, or the scavenging effect of the exhaust as a means to draw intake air in, but just go with it. —MAX). Any type of forced induction uses a mechanical means to increase the pressure of the intake air charge. That increased pressure is commonly known as boost.
By increasing the pressure of the intake charge, you push more air into the cylinder. More air, when mixed with more fuel, makes for a stronger combustion burn. The stronger burn pushes harder on the piston, which pushes harder on the crankshaft, which creates more operating power.
The two most common methods of forced induction are supercharging and turbocharging. A supercharger is an air pump that is driven by a mechanical link with the engine, often a belt that's connected to the crankshaft. A turbocharger is also an air pump, but it is driven by exhaust gas that is routed to it.
The supercharger's mechanical link to the engine means it is an "instant-on" device. As soon as the engine is turning over, the supercharger is working. The turbocharger, on the other hand, requires a build-up of exhaust gas pressure to spool up, so there can be a lag between the application of throttle and the boost in power.
So, the basic advantage of supercharging over turbocharging is that you get power increases right off idle with no waiting for turbo lag. Those in the pro-turbo camp will be quick to point out, though, that there is a certain parasitic loss of power from the crank having to drive the blower. So when choosing a forced-induction system, here's your first decision: Do you want instant, off-idle response? Or are you willing to trade a little low-end grunt for every last ounce of horsepower your engine can create? Don't make your decision yet; what we've yet to tell you about, Neuspeed's supercharger, may make this question moot.
Supercharger Types
Superchargers used for today's engines fall into two main types: Roots-style and centrifugal. The Roots-style blower, named for the brothers who invented it in the mid-1800s, is a positive-displacement air pump. It consists of a pair of lobed rotors that, by turning inside a case, push a high- pressure, dense air charge into the intake manifold. Most of the blowers you see on NHRA dragsters are Roots-style units, easily identified by their big, squarish, finned cases that sit on top of the engine blocks.
Roots-style blowers are also called external compression pumps because no compression of air actually takes place inside the blower case. This is the key point of difference between the Roots and centrifugal blowers. Centrifugal blowers are considered internal compression superchargers, since the impellers in a centrifugal blower compress air inside the unit itself, and then send the compressed air to the intake manifold. Many centrifugal blowers have round, snail-like cases that resemble turbochargers.
As with the turbo versus super- charging debate, there are arguments for and against the Roots and centrifugal blowers, too. Those who are pro-centrifugal point at heat as the Roots blower's number-one problem. The external-compression nature of the Roots pump creates more heat in the inlet air charge than the internal- compression centrifugal blower does, thereby making the air from a Roots blower less dense. So, the argument goes, even if the boost levels are the same, you'll get more power from five pounds of boost from a centrifugal blower than you will from five pounds of Roots blower boost.
However, Neuspeed's Bill Neumann chose a Roots-style blower as the basis of his 2.0L VW supercharger for several reasons, primarily for its reliability and longevity. "It requires less horse- power to drive it, and it doesn't have to turn as high rpm as a centrifugal blower to make horsepower," he said. "With a centrifugal you have to spin it 10,000 or 12,000 rpm to get any kind of pressure. With a Roots blower you get three pounds of pressure right off idle. The speed of the engine doesn't matter. Whether you're at three grand, or six grand, you get the same five pounds of boost."
Intake heat isn't being ignored by Neumann. His company is already developing an intercooler that can be easily retrofitted to those engines running his new blower.
Even without the cooler, and pushing a relatively mild five to seven pounds of boost, the new supercharger will deliver a "50-percent increase in horsepower," Neuspeed promises. While exact power output figures will vary depending on the engine, the company's first two Golf test cars fitted with the new blower are putting out 160 to 170 horsepower on the chassis dyno.
Let's put those numbers in perspec-tive: We're talking about an engine that, in stock trim, is rated at 115 hp at the flywheel. Typically, the drivetrain will soak up anywhere from 20 to 30 percent of the engine's power, so the stock 2.0 sends anywhere from 75 to 85 hp to the ground. Do the math. Those 160 to 170 horses are easily double the stock motor's output. How did Neuspeed do it?
Inside the Neuspeed Supercharger
Neuspeed spent nearly a year developing its 2.0L supercharger. The process began with the company examining what was already on the market, paying particular attention to "the failures of others," said Neumann. Neuspeed worked closely with the supercharger division of Eaton, which also manufactures blowers for Ford Motor Company and Jackson Racing, among others.
But Neumann didn't want a "me, too" blower. "It had to be an entirely new product," he told us, one that was "easy for the customer to install. That's the Neuspeed way." So the company bought a couple of junkyard engines, mounted them on stands, and began prototyping. Wooden mock-ups came first, to see what exactly would fit and where. Then came months of CAD drawings, refinements to the wooden mock-ups, and then molds for the prototype aluminum casting. Let's not forget the added worry over where to fit all the miscellaneous related parts and pieces—the brackets, throttle cable, intake plumbing, and the like.
The end result is an aluminum piece that integrates the top of the intake manifold and the blower case in one unit. It's held in place using only five bolts, hooks up to all the stock plumbing locations, and can be installed in only two to three hours. The supercharger will work on eight-valve 2.0L engines in Golf IIIs and Jetta IIIs ('93–'99½), Golf IVs and Jetta IVs ('99½ and up), and New Beetles ('98 and up), though only the Mk IV engine versions currently carry CARB emissions approval (More on that later.—MAX).
The guts of the blower are in Eaton's 45-cubic inch rotor group—the rotors, back bearings, front-bearing group and drive gears. These are the same pieces used in Mercedes-Benz and Jaguar superchargers, so Neumann was confident in the equipment. Eaton made a significant improvement to the Roots brothers' original blower pump design in the form of a helical twist to the rotors. This twist, along with proprietary inlet and outlet port geometry, reduces air pressure variations, improves the pump's efficiency, and lowers the blower's noise level. Another Eaton feature, a vacuum-operated bypass valve, recirculates the blower's air flow when boost is not needed (At idle and during light throttle, cruising applications.—MAX) to lighten the pressure on the engine and help to maintain near-stock fuel economy levels.
Neuspeed also works with another company, Magnuson Products, which machines the supercharger's nosepiece and drive-belt pulley, and then assembles and installs the complete assembly in the housing. Magnuson, located in Ventura, California, is the sole aftermarket distributor of Eaton superchargers and rotor groups. It is also Eaton's sole remanufacturing facility, so if any blowers develop a problem, they will go to Magnuson for troubleshooting. Neumann also did some tweaking to the manifold itself. Though the ports match perfectly where they join with the lower manifold, the intake runners are longer and smoother for better airflow. The plenum has been reworked, too, to provide a ram effect to the air entering the lower manifold.
Related Modifications
As we mentioned in our initial explanation of how a supercharger works, it is essentially a pump that pushes more air into the cylinders, which takes care of one half of the combustion equation. But what about fuel? Ignition timing? And are there other modifications needed to use a blower on a stock VW engine?
While the blower unit was under development, Bill Neumann's son, Aaron, was working on computer programming to get the air/fuel/spark combination just right. "It wasn't just a matter of fattening up the fuel," Aaron explained. "At certain points in the rpm range, you don't need a lot more fuel, so the chip fattens, or leans, the fuel delivery as needed." As for ignition timing, "an engine wants advance to make horsepower," he said, "so we wrote a special program that makes the engine more lively, more driveable." The timing advance they could put into the engine "was dependent on the fuel octane available today," which is 91 or 92 octane at best, Aaron added. So those customers running the new blower should make sure they buy their gas from a "major fuel supplier to make sure they're getting the full 91 or 92 octane."
If you're buying a blower for a Mk III engine, the new computer program comes on a P-Chip that plugs into the engine's computer. For the later cars with soldered chips, the entire ECU must be sent to Neuspeed for custom programming. Neuspeed promises one-day service on the computer.
There's another big difference between the Mk III and IV engines: intake plumbing. While Neuspeed tried to keep the installation looking as factory as possible, it faced one big packaging challenge. On the Mk III cars, the airbox is on the passenger's side, unfortunately, so is the supercharger's snout and drive belt. The new throttle body is on the driver's side. So, Neuspeed had to develop an intake tube that runs around the engine compartment to the other side of the blower. In Mk IV cars, where the throttle body and the airbox are both on the driver's side, the intake plumbing is simpler and can utilize the factory flex hose and couplings.
As we mentioned earlier, currently only the Mk IV version of the supercharger is 50-state smog-legal. Was that a function of the intake plumbing, we asked? "No, CARB says that engine carries the latest emission devices—the OBD II equipment," Neumann explained. "If it passes testing with that stricter level of emissions control, it's easier to retro to the earlier models." So look for an E.O. number on the Mk III cars soon.
We also asked if any other engine modifications were necessary to run the blower. When you're building a blown version of a big Detroit V-8, for example, it 's often necessary to beef up the motor's bottom end with four-bolt main bearings, stouter rods, and so on. A lower compression ratio is also recommended to keep the cylinder heads from blowing right off the block.
But Neumann said no. "You have to go back to the engine's German roots, the way they're driven back there. In every single gear the engine is maxed to the rev limiter with the accelerator to the floor. That's just the way those guys drive. VW builds bulletproof engines, designed for flat-out driving. Back in the '70s and '80s, in the early days of turbocharging, we were running 25 pounds of boost, and there weren't any mods needed. We had no problems with the head gaskets or the rods." Okay, so there aren't any necessary modifications. What if a customer wants to make some tweaks of his own? Like maybe add a P-Flo filter to the intake? Or one of Neuspeed's exhaust systems? "Those are already smog-approved, so it should be fine," Neumann said. In fact, he hinted that a Stage 1 stainless steel intake housing with a P-Flo filter is on the Neuspeed drawing boards, as are the aforementioned intercooler and camshafts. So, 2.0L fans, it sounds like the horsepower gains seen in the test cars are just the beginning.