Jackson Racing Rotrex Supercharger System Info and Discussion

[Sellout]

Originally Posted by Calum

Care to expand on it then? I'd love to know more about what they're doing and how it works. I thought about searching for the patent, but laziness took hold. Well, that and the hangover.

There's a gif on this page that does a pretty good job of explaining how it works. http://www.rotrex.com/Home/Technology/Product_Concept

At least it does a better job than I can explain with my simple vocabulary...

What's not explained well, by Rotrex themselves or the people who sell them, is that the planetary drive is not magic. It doesn't uncouple the impeller from the crank shaft speed and allow the boost to ramp up faster than the other centrifugals on the market. It doesn't spool to full boost early in the RPM band and give you a dyno sheet that looks like a turbo car.

If there's more midrange with a Rotrex, it comes from the efficiency of their traction drive and the impeller design (compressor map) itself. Not from earlier boost onset.

[DJCarbine]

Originally Posted by Calum

Care to expand on it then? I'd love to know more about what they're doing and how it works. I thought about searching for the patent, but laziness took hold. Well, that and the hangover.

I believe this to be correct for the most part.......


So I thought the rotrex was a planetary gear system when they introduced it, but no one ever really got in depth about the gear system...

As I understand it, its basically a planetary gear system BUT smooth rollers instead of gears


Thats why the non-newtonian fluid is needed, as the fluid plays a part in the drive efficiency in the gearset and which allows the impeller to spin faster under high load than it would normally with a newtonian fluid

I could be way off, but its all the info I can find on the net

[Sellout]

allows the impeller to spin faster under high load than it would normally with a newtonian fluid

That's exactly what I was talking about before... This just isn't true. The traction fluid simply makes sure that those smooth surfaces don't slip.

[DJCarbine]

Originally Posted by Sellout

That's exactly what I was talking about before... This just isn't true. The traction fluid simply makes sure that those smooth surfaces don't slip.

It doesn't alter the characteristics of the "slip" due to load? I thought that was the entire point of their traction drive and what made it unique

Off to do more research, its not a very widely discussed topic

[Sellout]

Originally Posted by DJCarbine

It doesn't alter the characteristics of the "slip" due to load? I thought that was the entire point of their traction drive and what made it unique

Off to do more research, its not a very widely discussed topic

They (rotrex) claim that it alters the transfer of torque as needed. What that means is that only as much torque as is needed to spin the impeller gets transferred to the impeller drive shaft.

Clever marketing. An all wheel drive Porsche pulling a wheelie on a drag-strip only transfers enough torque to the front wheels to make them spin in the air. This is just how the physics of a drivetrain work.

The reality is that in order to dynamically accelerate the impeller shaft at a higher rate as needed, something in that drive system absolutely must be adjustable for a different gear ratio. (Think CVT) Otherwise it's just not possible.

As for adjustments based on load, the supercharger will never see anymore "load" than what is needed to spin the impeller, and that load isn't going to change from one pull to the next. The real benefit of their drive system is that it's nearly silent. That's pretty much all.

I can remember when the Kraftwerks system was being developed for the S2000. There was a whole lot of speculation about Rotrex's wording and what it meant. The general consensus among damn near everyone on S2Ki was that it was going to be magical. The planets were going to align, polar ice would stop melting, the middle east would be peaceful, and a centrifugal supercharger would rival a twin screw for torque delivery. Then the system was finished, and there were a few of us who were not surprised in the least to see that the boost curve and resultant dyno sheet was damn near identical to every other centrifugal. I can't call it snake oil because clearly the traction drive does work, and rotrex doesn't come out and say that it does what everyone on the forums expects it to. You just can't forget that the impeller is tied directly to the crankshaft. As such, if you want 10 psi at 3k rpm, you're going to have more than 10 psi and much warmer air at 6k rpm.

[DJCarbine]

Originally Posted by Sellout

They (rotrex) claim that it alters the transfer of torque as needed. What that means is that only as much torque as is needed to spin the impeller gets transferred to the impeller drive shaft.

Clever marketing. An all wheel drive Porsche pulling a wheelie on a drag-strip only transfers enough torque to the front wheels to make them spin in the air. This is just how the physics of a drivetrain work.

The reality is that in order to dynamically accelerate the impeller shaft at a higher rate as needed, something in that drive system absolutely must be adjustable for a different gear ratio. (Think CVT) Otherwise it's just not possible.

As for adjustments based on load, the supercharger will never see anymore "load" than what is needed to spin the impeller, and that load isn't going to change from one pull to the next. The real benefit of their drive system is that it's nearly silent. That's pretty much all.

I can remember when the Kraftwerks system was being developed for the S2000. There was a whole lot of speculation about Rotrex's wording and what it meant. The general consensus among damn near everyone on S2Ki was that it was going to be magical. The planets were going to align, polar ice would stop melting, the middle east would be peaceful, and a centrifugal supercharger would rival a twin screw for torque delivery. Then the system was finished, and there were a few of us who were not surprised in the least to see that the boost curve and resultant dyno sheet was damn near identical to every other centrifugal. I can't call it snake oil because clearly the traction drive does work, and rotrex doesn't come out and say that it does what everyone on the forums expects it to. You just can't forget that the impeller is tied directly to the crankshaft. As such, if you want 10 psi at 3k rpm, you're going to have more than 10 psi and much warmer air at 6k rpm.

This makes sense

[Poodles]

Yeah, the only real advantage the Rotrex system has is that it's more efficient than using gears (supposedly). Less drive loss meaning it doesn't take as much power from the engine to spin.


Twin screws are notoriously bad about this.

[D K]

There are major differences in the overdrive mechanisms between the Vortech superchargers and the Rotrex.

Vortech uses a gear setup where Rotrex uses a planetary type setup.
The issue with any gear driven mechanism is noise. In order to combat noise, the gears are designed as helical gears.
Helical gears create thrust. This axial thrust takes away from the efficiency of the drive unit.
A spur gear would be more efficient, but the noise would be dreadful.
Even a typical gear type planetary setup would be very noisy.

Enter Rotrex.
They came up with a planetary setup that doesn't use gears. It uses roller bearings, so you get the best of both worlds: no noise and no thrust load.
Because of the extra efficiency, the gearing can be more aggressive, which gives the Rotrex a huge advantage at lower rpm.

The tolerances are so tight between the sun/planet roller and the planet/ring roller that the ring gets squeezed during the manufacturing process in order to fit the planet rollers in the gap.
That's the reason for the 'special' fluid.

[OmarGC]

Originally Posted by D K

There are major differences in the overdrive mechanisms between the Vortech superchargers and the Rotrex.

Vortech uses a gear setup where Rotrex uses a planetary type setup.
The issue with any gear driven mechanism is noise. In order to combat noise, the gears are designed as helical gears.
Helical gears create thrust. This axial thrust takes away from the efficiency of the drive unit.
A spur gear would be more efficient, but the noise would be dreadful.
Even a typical gear type planetary setup would be very noisy.

Enter Rotrex.
They came up with a planetary setup that doesn't use gears. It uses roller bearings, so you get the best of both worlds: no noise and no thrust load.
Because of the extra efficiency, the gearing can be more aggressive, which gives the Rotrex a huge advantage at lower rpm.

The tolerances are so tight between the sun/planet roller and the planet/ring roller that the ring gets squeezed during the manufacturing process in order to fit the planet rollers in the gap.
That's the reason for the 'special' fluid.

To this day I've never seen it

[Sellout]

Originally Posted by OmarGC

To this day I've never seen it

That's because it doesn't exist. The advantage is silence and a little less drive-loss as mentioned above.

Enter Rotrex.
They came up with a planetary setup that doesn't use gears. It uses roller bearings, so you get the best of both worlds: no noise and no thrust load.
Because of the extra efficiency, the gearing can be more aggressive, which gives the Rotrex a huge advantage at lower rpm.

You need to think about this a little more. The reason for the huge internal step-up gearing is because they use a small impeller. It needs to be able to spin to 6 digit RPM numbers to deliver the airflow that the other manufacturers get with a larger impeller at half the RPM. This isn't some huge advantage, it's just a different design.

[OmarGC]

Originally Posted by Sellout

That's because it doesn't exist. The advantage is silence and a little less drive-loss as mentioned above.

Exactly what I was getting at.

[Superstar]

How reliable is the CARB tune? Does modify the updated transient timing tables tunes that are related to the direct injection issue?

Forced induction sounds great for this motor, but not when it will impact or accelerate the deterioration of the DI seal.

[CSG David]

Originally Posted by Superstar

How reliable is the CARB tune? Does modify the updated transient timing tables tunes that are related to the direct injection issue?

Forced induction sounds great for this motor, but not when it will impact or accelerate the deterioration of the DI seal.

That is a loaded question since every kit from CARB legal to custom tuned supercharged, turbocharged, or even NA setups will all be at risk for that failure regardless of what you do with stock or FI setups. As for accelerated failure of DI seals, the rate is still going to be the same or possibly slower. Tuning appears to have some effect on decreasing DI failures, but we noticed that changing the way you drive in a performance setting also cuts down on the failure rate too.

[Calum]

I wonder if the rotrex drive system is designed to slip some at high rpm.

I understand that the differences in low end torque delivery aren't there, I've seen some dynos to. But I wonder if that was a part of the design, to make it slip some at high rpm so it can be spun faster at low rpm without over spinning it. Kinda reminds me of quick bleed down lifters if that is the case.