MuscleJunkie
Elite Explorer
- Joined
- April 14, 2007
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- 1,078
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- Year, Model & Trim Level
- '00 Ford Explorer LTD AWD
So I’ve come to the determination that I need to switch out my Ford Motorsport SVO Powerdyne Supercharger ( Big White - Ford Racing Powerdyne Installation Thread ) which is belt driven, for the Powerdyne XB-1A Supercharger - a gear driven supercharger.
I’ll later post a detailed explanation about the reasons for my choice but from my previous posts a lot of that has already been explained.
In the meantime, here is some information on the XB-1A for those who are not familiar with it. I know that there have been one or two forum members here many years ago who went this route as well.
See attached photos
(Impeller photo)
No problem spotting the differences here. The taller impeller at left is from the belt-drive blower, the shorter impeller at right is from the gear drive. The gear-drive’s impeller also features more heavily curved blades, which trade some lower-rpm airflow for more top-end cfm.
Powerdyne says that whereas the belt-drive blower has always had a smooth, linear power delivery, the gear drive has a distinct hit, coming online in the engine’s midrange, “like nitrous”
This was the impeller available 20 years ago. Now you can chose impellers comparable to all of the Vortec supercharger trims with similar expectations. I’ve decided to go with a mid range billet SI trim option.
(Internals photos)
Following traditional centrifugal blower practice, the large input shaft - the one the blower drive pulley is attached to - is a two-piece assembly. The shaft and the large gear are separate pieces. The output shaft - the one the impeller bolts to - is a single piece. As with a transmission input shaft, the blower output shaft has its gear cut right into it. In this photo the input shaft is taller and is showing a keyway; the output shaft is mainly covered by its bearing. A belt-drive Powerdyne lurks in the background.
Powerdyne blanked out its own gears, and had a specialist company put the final finish on the gear teeth. As do other blower makers, Powerdyne had its volutes cast at a foundry, but did all machining and assembly in-house. With the help of multiple CNC-machining centers, Powerdyne was able to whittle out the rest of the blower itself. The units built today are said to have many additional small improvements since the original builds.
(Seal photo)
The trickiest place to seal on a centrifugal blower is between the gearbox and the volute, where the output shaft passes through. Powerdyne used this trick double-lip seal for that job. Run your finger over it and you’ll find the seal is surprisingly hard, being graphite impregnated. It also looks unusual, with the two seal lips pointed in opposite directions. I’m assuming the newly built units use the same type of seal, but that hasn’t been clarified.
(Dowl Photo)
Standard-style dowel pins are used to locate the blower cover to the blower housing. For many years most centrifugal blowers used precision-ground diamond pins for this job, but they have proven unnecessary with CNC-machining, and they are troublesome to work with as they often break off when removal is attempted. Dowel pins have eliminated such troubles.
(Breakdown photo)
Although it shows a clear family resemblance, the Powerdyne XB-1A gear-drive supercharger does not share one major part with its belt-drive brother. Yet the two interchange in the same brackets, allowing the gear drive to replace a belt drive, if desired.
(Bearing photo)
Each of the two shafts in the XB-1a rotate in bearings. The large ball bearing on the input shaft is garden-variety stuff, but this smaller bearing on the output shaft is more than that. An “angular contact” bearing, it uses a special separator internally to handle the unusual loads made on it by the impeller. Pricey specialty bearings such as these are one reason superchargers cost so much. I’m assuming that the newly built units use a comparable or improved bearing of those used originally on the XB-1A as pictured in this photograph from 20+ years ago.
I’ll later post a detailed explanation about the reasons for my choice but from my previous posts a lot of that has already been explained.
In the meantime, here is some information on the XB-1A for those who are not familiar with it. I know that there have been one or two forum members here many years ago who went this route as well.
See attached photos
Powerdyne Gear Drive XB-1a Supercharger
Not only is the gearbox different between Powerdyne’s belt- and gear-drive blowers, but the impellers and volutes are too. Note the gap between the flat disk area and the outer housing of these two volutes. The one with the wider gap (at right) is for the new gear-drive unit; the one at left is a belt-drive volute. Clearly the turbine sections of the two blowers are not interchangeable. Pay little attention to the difference in outlets; the 90-degree outlet as shown here on the belt-drive volute is what yoi see on Mustangs with the gear drive too. The straight outlet on the gear-drive volute is what is used on our Explorer.(Impeller photo)
No problem spotting the differences here. The taller impeller at left is from the belt-drive blower, the shorter impeller at right is from the gear drive. The gear-drive’s impeller also features more heavily curved blades, which trade some lower-rpm airflow for more top-end cfm.
Powerdyne says that whereas the belt-drive blower has always had a smooth, linear power delivery, the gear drive has a distinct hit, coming online in the engine’s midrange, “like nitrous”
This was the impeller available 20 years ago. Now you can chose impellers comparable to all of the Vortec supercharger trims with similar expectations. I’ve decided to go with a mid range billet SI trim option.
(Internals photos)
Following traditional centrifugal blower practice, the large input shaft - the one the blower drive pulley is attached to - is a two-piece assembly. The shaft and the large gear are separate pieces. The output shaft - the one the impeller bolts to - is a single piece. As with a transmission input shaft, the blower output shaft has its gear cut right into it. In this photo the input shaft is taller and is showing a keyway; the output shaft is mainly covered by its bearing. A belt-drive Powerdyne lurks in the background.
Powerdyne blanked out its own gears, and had a specialist company put the final finish on the gear teeth. As do other blower makers, Powerdyne had its volutes cast at a foundry, but did all machining and assembly in-house. With the help of multiple CNC-machining centers, Powerdyne was able to whittle out the rest of the blower itself. The units built today are said to have many additional small improvements since the original builds.
(Seal photo)
The trickiest place to seal on a centrifugal blower is between the gearbox and the volute, where the output shaft passes through. Powerdyne used this trick double-lip seal for that job. Run your finger over it and you’ll find the seal is surprisingly hard, being graphite impregnated. It also looks unusual, with the two seal lips pointed in opposite directions. I’m assuming the newly built units use the same type of seal, but that hasn’t been clarified.
(Dowl Photo)
Standard-style dowel pins are used to locate the blower cover to the blower housing. For many years most centrifugal blowers used precision-ground diamond pins for this job, but they have proven unnecessary with CNC-machining, and they are troublesome to work with as they often break off when removal is attempted. Dowel pins have eliminated such troubles.
(Breakdown photo)
Although it shows a clear family resemblance, the Powerdyne XB-1A gear-drive supercharger does not share one major part with its belt-drive brother. Yet the two interchange in the same brackets, allowing the gear drive to replace a belt drive, if desired.
(Bearing photo)
Each of the two shafts in the XB-1a rotate in bearings. The large ball bearing on the input shaft is garden-variety stuff, but this smaller bearing on the output shaft is more than that. An “angular contact” bearing, it uses a special separator internally to handle the unusual loads made on it by the impeller. Pricey specialty bearings such as these are one reason superchargers cost so much. I’m assuming that the newly built units use a comparable or improved bearing of those used originally on the XB-1A as pictured in this photograph from 20+ years ago.
