Steve Turner
Former Editor, 5.0 Mustang & Super Fords
June 1, 2000
Photos By: Chuck James

Step By Step

View Photo Gallery
138_71z 1997_ford_mustang_gt Engine_viewP95272_image_large
From this angle the P-1SC prototype looks like any other centrifugal supercharger. The giveaway will always be the dipstick in the top side of the blower. At press time ATI had not decided whether SCs will feature a drain plug or a deep dipstick tube to allow pumping out the lube. All SCs will feature helixed impellers, and ATI is working to standardize the dimensions so those originally built for the street may be upgraded to race specs. The upgrade will consist of new gears and an even better bearing.
ATI has worked hard at keeping this arrangement under wraps while the proper patents were applied for, but we got one of the first looks inside. Most of the internals are standard ProCharger fare, with the large input shaft riding on a heavy-duty bearing and spinning the impeller shaft at a 4.44:1 ratio. The trick is the oil pump pointed out here. According to ATI’s Dan Jones, most centrifugal blowers are tripling the speed rating of their bearings, while working well under the intended load rating. This environment requires strict attention to lubrication. This pump feeds the bearings with near-direct oiling at low rpm and misting at high rpm. Because of the added cost required in building the SCs, they will command prices 5-10 percent higher than oil-fed blowers.
Besides having the blower housing cast in a permanent mold for improved structural durability, ATI is taking a unique approach to building the gearsets for the self-contained blowers. “Our goal is to create a blower that doesn’t crash the same way traditional blowers crash,” Dan explains. “You can say that, we, the gear-driven blower manufacturers, build our blowers with overly strong gearsets, because we want to avoid physically dropping gear teeth into a customer’s oil pan. That said, we will be focusing on more fusible links, if you will. If the gears can be designed so that under a bad failure, the blower goes into Neutral, you’re not going to get pieces of the impeller going into the intake.”
Comparing the P-1SC’s 6-1/2-inch impeller versus the 8-inch D-3 impeller shows the difference between a race blower and a street blower. However it’s not really the diameter of the wheel that controls the “size” of the blower, it’s the area between two vanes that determines the air-moving ability of the blower. What we also noticed about ATI’s latest billet impellers is a much smoother finish. Though ATI has always maintained the rugged impellers never suffered power loss from the grooves left over from the CNC machines, the latest wheels show the attention to detail customers have come to expect. Dan says all SCs will also feature helixed (curved-blade) impellers as a response to customer expectations. Curved-blade impellers are said to help produce low-end boost, but he says, in practice, there is little performance between curved and straight wheels.

We've seen a lot of superchargers here at 5.0 Mustang & Super Fords, because most of the supercharger companies were built by starting with kits for 5.0s. One such company is Accessible Technologies Inc. in Lenexa, Kansas. ATI is the company that first brought intercooled supercharging to the Mustang market. Its D-series blower tore up the first two years of Renegade racing and has now taken the Pro 5.0 world by storm. Something besides barbecued beef is cooking in Kansas, so when the ever-zealous Dan Jones, president of ATI, called us offering a look at the company's latest blower technology in prototype form, we jumped at the chance.

Off the bat we assumed the new technology meant some new giant-slaying race blower or trick new impeller. Without reiterating what my high school English teacher said about assuming, it's not hard to figure out we were wrong, really wrong. You see, ATI has invested considerable time and money to go back to the future. We're not talking DeLorean time machines here, but ATI is breathing high-performance life into a blower concept we had long ago written off as one meant for low-boost street applications only.

It's a risk to say the least, but from what we've seen ATI is about to rewrite the repu- tation of a self-contained supercharger. That's right, installing the new ProCharger SC doesn't require punch- ing a hole in the oil pan!

Don't get started thinking this is some low-performance blower fit only for your sister's V-6 Mustang, however. The street version of the ProCharger SC will be good for up to 20 pounds of boost and 700 hp, while the racier version will support up to 1,100 hp. But we're getting a little bit ahead of the story here. The reason this supercharger offers more durability and more power potential than previous, self-contained iterations is that it retains the rugged gear-drive mechanism we've come to associate with centrifugal blowers.

"...We took the components--that we found through the structural testing and race victories--of the D-series that were of reasonable cost and put them into this blower," Dan explains. "We knew that the bigger, inside-bolted shaft is a critical factor in maintaining shaft rigidity, which keeps the impeller from ever running out of its path. Next, we realized the big input shaft bearings we use in the D-series and the big supporting shaft gave us the ability to carry a tremendous belt force."

Essentially, the internals of the SC are a pared-down version of the original D-series. Rather than using twin bearings, the SC uses a single bearing on the 7/8-inch input shaft. Like the input shaft in the D-series, this shaft uses the aforementioned bolt to retain the impeller. According to Dan, this method does a much better job of ensuring shaft balance than the more commonly used nut.

This improved balance reduces the chance of the impeller crashing into the blower housing. A durable transmission is certainly a reassuring presence in a self-contained blower, but you're probably asking how a gear-driven blower can be run without oil-feed and -return lines. The secret is an oil pump. Thanks to impetus from the rigorous industrial and marine markets the system was originally designed for, ATI was able to expend time and money to develop just the right pump. Owners of high-powered boats are particularly resistant to punching a hole in their engines' oil pans. These engines likely cost more than your car, so even the remote possibility of filling the pan with exploded blower bits is an instant turn-off. Even though ATI has done well supercharging boats, it wanted to take things to the next level.

Fortunately, we get to come along for the ride too, as punching the oil pan has long been a centrifugal cross to bear. What is equally exciting and frustrating is the simplicity of the solution. Why didn't someone do it before? The solution was initially dismissed as too simple to meet Dan's four main requirements: The pump should add little or no heat to the lubricant, it should operate with low oil levels, it should require no priming, and it should be bulletproof.

What could possibly meet all these goals? How about a simple sprocket acting as an oil slinger. This sprocket-shaped wheel works well because it distributes oil in accordance with the bearing's needs. At low rpm it chugs through the oil at the bottom of the blower case like the waterwheel powering the old mill on the river. As such, it provides the bearings with the direct oil they need at low rpm. At higher rpm the slinger creates states of cavitation in the oil reservoir, thus creating the oil mist the bearings want at higher rpm. It's quite ingenious.

The result of this creativity means your life will get easier. Though ATI has spent much of the last year developing this new core technology, its new focus will be packaging the SC blower with brackets, intercoolers, and the like for the applications it already services, like 4.6 and 5.0 Mustangs, plus many more new applications like trucks and SUVs. Dan Jones says he just wants to grow the supercharger market with his new product, but in the process he just may put punctured oil pans in the performance history books.

Horse Sense:
Though the prototype ProCharger SC we tested featured the same 4.44:1 step-up ratio as its D-series predecessor, future versions may feature a 4: or 4.15:1 because ATI is having difficulty getting the boost levels low enough on its base kits featuring reverse-rotation blowers, like those used on 4.6 Mustangs. It seems ATI can't fit a large-enough pulley, given the mounting confines, to sufficiently reduce the boost--a good problem to have.