Rotrex superchargers

[Caustic]

So, as I'm poking around other car websites looking at forced induction, I noticed a name continuing to pop up. Rotrex superchargers. There are a lot of different car makes out there using their superchargers in kits, many decently priced. There is even one for the MDX.

http://www.rotrex.com/Home/Supercharger_Experience/Kits_Cars.aspx
That a list from Rotrex themselves, but I'm sure there are more kits out there than they list.

I really don't know much about them, but continually seeing the name pop up made me curious. Is there a reason we only see Autorotor, Whipple (essentially the same kit) and the occasional Paxton? Could an economical (relatively) kit be created with real intercooler options? Is this a better possibility to avoid heat soak like the Comptech kits do? Anyone know or have experience with the Rotrex stuff?

 

[liftnot]

There are many Rotrex kits out there BUT not for our car:frown:
It doesn't appear to have the common heat soak problem with SC and it runs much cooler overall unlike the turbo which cooks everything around it. and its small, not heavy= nice packaging with little plumbing.

I am not knocking the hp/torque increase from SC/Turbo.....but they have been around forever and I like to have another option.

During 2006 Atom Fest in Hallett OK, Pete from OC had a Honda atom with Rotrex/IC and it sounded like a turbine coming down the straight....so Wicked!

Here is a pix in a F-car

 

[RYU]

It's a popular and proven design. Though I doubt any vendor will step up since tooling involved for even the pulley system alone will be decently high. Coupled with a small niche market... there's slim to no chance of seeing a commercially available kit for the NSX.

It's not like a turbo system where any good welder can put a kit together relatively easily. Pulley setups require a lot more machining and precision.

 

[pvmike]

There is a long running ad on autotrader, a 92 with 50k miles, with a rotrex.

This 92 NSX is a custom one of a kind rocket. Rotrex supercharger and custom made intercooler. 100hp and 80 ft-lbs. of torque increase over stock. Custon stainless steel piping, brackets, pulleys. Cantrell headers, custom exhaust piping and Billy Boat tuned muffler. New clutch installed at 40k miles All engine work performed and dyno-proven by Mechanics Direct Modifiers of Boston in 2008 at 48k miles

Hatch scoop and intercooler set up kills visibility.

 

[docjohn]

The gruppe M also obstructs the rear view,but looks impressive sitting atop the engine.

 

[Caustic]

Hmm, Rotrex in a Novitec Rosso. I never knew!

But that setup in the NSX is crazy. I know that was a one off, but I would never want to lose my rear vision like that. I'm sure there is a better way.

Just kind of a shame because everything liftnot said is true, its small, doesn't sit on top of the engine to bask in the heat, and seems pretty efficient. I see kits for 370z's pushing their whp to almost 450. Is it really that much easier to turbo?

 

[NetViper]

I have wondered myself why there was never a Rotrex sc NSX. They sound excellent. Not many downsides that I saw.

 

[Nukem]

I have never even heard of this system before. What makes it different from other superchargers that are available for the NSX?

 

[CL65 Captain]

Self contained oiling system, extremely efficient, more like a belt driven turbo than a roots type like the Whipple/Autorotor

Also a Russian company is making a two speed auto transmission for one. Last I checked it was still in development, but cool as hell.

 

[liftnot]

As much as I like to have more hp/tork, Roots type SC are just too heavy especially its all top end static weight (more with IC) and its based on 1960 technology, not that is a bad thing like NASCAR, just saying. I know, our cars should came this way and you won't feel the weight gain and Comptech SC is a fine product.

Turbo is also been around for a long time(ball/journal bearing), although you can mount a single/twin turbo at a very low CG position like F1 or Le Mans, it frys everything around it if you don't exit the hot air effectively which is ok on a race car app, a street car wiring harness become crispy over time. And even w/o lag, lots of plumbing affect the throttle response and that is just physics. Again, lots of fine selections for our cars and I wish the Borg-Warner unit can be more street friendly.

ITB is also been around but many bash it due to little hp/tork gain and high cost but it will lose weight on the top and increase throttle response if that is how you roll. Thx to SOS, at least there is one solid option for ITB.

Rotrex seems to address all of my concerns at least on paper. but like Regan said, our market is too small for any vendor to design a proper set up and to pass CARB is not a value-added proposition.

 

[L_RAO]

Based on its dimensions and its drive mechanism, I don't see why someone could simply buy a used BBSC kit and retrofit it to drive the Rotrex.

That, along with modern-day fuel (ID 725s) and engine managment (AEM EMS), should make for a very nice upgrade for the NSX.

 

[TURBO2GO]

Interesting thought....

 

[E-Nough Logic]

As much as I like to have more hp/tork, Roots type SC are just too heavy especially its all top end static weight (more with IC) and its based on 1960 technology, not that is a bad thing like NASCAR, just saying. I know, our cars should came this way and you won't feel the weight gain and Comptech SC is a fine product.

Turbo is also been around for a long time(ball/journal bearing), although you can mount a single/twin turbo at a very low CG position like F1 or Le Mans, it frys everything around it if you don't exit the hot air effectively which is ok on a race car app, a street car wiring harness become crispy over time. And even w/o lag, lots of plumbing affect the throttle response and that is just physics. Again, lots of fine selections for our cars and I wish the Borg-Warner unit can be more street friendly.

ITB is also been around but many bash it due to little hp/tork gain and high cost but it will lose weight on the top and increase throttle response if that is how you roll. Thx to SOS, at least there is one solid option for ITB.

Rotrex seems to address all of my concerns at least on paper. but like Regan said, our market is too small for any vendor to design a proper set up and to pass CARB is not a value-added proposition.

Center of gravity and weight from the supercharger.....really? You are stretching to convince yourself here. If you're melting wiring harnesses it's not because you are turbocharged it's because whoever made/installed the kit was a moron.

The Rotrex isn't very different than any other centrifugal supercharger, similar to a paxton or vortech blower. All of which can be intercooled in the same fashion, and hopefully not like the NSX pictured above with the intercooler blocking rear view vision. I think an A2W setup would be a better idea. One may be better than the other or more efficient but all function the same.

It does have a couple advantages to consider but no one has mentioned the biggest drawback of this style of supercharger, area under the curve. These superchargers typically make peak torque at peak rpm. They are not instant on like positive displacement superchargers IE whipple or CT. Essentially they combine the worst aspects of the turbo, lag and the worst aspects of the supercharger, efficiency.

 

[liftnot]

Everyone has different approach when they mod their cars. Its physics, thats all.
I like ITB, to increase the efficiency of the engine w/o increase internal stress of the oem design. And to lose 35lbs top end weight makes sense to me. Another Primer who has de SOS twin saz its fast as hell and as reliable as oem and he gets 16mpg overall....he is totally happy.

The few who did the ITB mod got crucified here for spending so much $$ and gaining so little hp/tork but Ravi can get 27 mpg w/ a solid tune, thats pretty good and thats important to me.

I just don't want to chase my tail dealing with the heat issues.

 

[CL65 Captain]

It does have a couple advantages to consider but no one has mentioned the biggest drawback of this style of supercharger, area under the curve. These superchargers typically make peak torque at peak rpm. They are not instant on like positive displacement superchargers IE whipple or CT. Essentially they combine the worst aspects of the turbo, lag and the worst aspects of the supercharger, efficiency.

Not true for the Rotrex. In fact they are partnering with a company that is developing a variable speed drive for it. Do a little reading and you will see that it's not your daddy's centrifugal supercharger.

 

[blodi]

Based on its dimensions and its drive mechanism, I don't see why someone could simply buy a used BBSC kit and retrofit it to drive the Rotrex.

That, along with modern-day fuel (ID 725s) and engine managment (AEM EMS), should make for a very nice upgrade for the NSX.

Not true for the Rotrex. In fact they are partnering with a company that is developing a variable speed drive for it. Do a little reading and you will see that it's not your daddy's centrifugal supercharger.

Ok, now you guys got me thinking.........

My current BBSC setup has a 10lbs pulley on it (hits 9.8 on the logs).
I love the kit, but my only complaint is that it is all top end power....really nothing until 5-6K. I was thinking of putting a 15lbs pulley on and a wastegate setup to limit it to the same top end boost, but this would effectively (in theory) give me 50% more boost across the rpm range and boost up the mid range. But this also would work the whole system 50% harder and drive up the intake temps I'm sure......Maybe its worth some investigation into this Rotex setup......I'm sure Cody could fab something up using my BBSC.....:tongue:

 

[Caustic]

See, this is what I'm talking about! A little experimentation! Blodi, if you do get something going, keep us updated.

 

[E-Nough Logic]

Not true for the Rotrex. In fact they are partnering with a company that is developing a variable speed drive for it. Do a little reading and you will see that it's not your daddy's centrifugal supercharger.

Yes it is true for a Rotrex, take a look at any rotrex dyno graph, they look just like any other centrifugal supercharger. You can't argue with me it is simple gearing, at peak engine rpm the supercharger is at peak rpm as well. Note peak supercharger RPM does not always mean peak airflow. Peak airflow could occur earlier if you run too small of a pulley and overspeed the compressor out of its efficiency range which of course could cause excess heat and possibly long term reliability problems. So when used within its designed limitations peak torque will occur very late in RPM range doesn't matter if its a rotrex, or paxton.

I won't argue that its not more efficient than the others just that it works in the same manner. I believe they use smaller compressor wheels but gear them up more to flow more air similar to turbocharger speeds, at redline of course.

They have not developed the gearbox yet, which I'm sure will cause even more parasitic loss on the drivetrain. Keep in mind the same gearbox could be designed and used on any centrifugal supercharger because they all function the same.

 

[RYU]

I would like to also mention that for a street driven car the stock CTSC works quite well. I've monitored my IATs religiously. The temps come down 20-35+ degs when you're off boost rolling your way to the next stop light after a WOT run even in 85+ deg ambient.

The heatsoak issues are for prolonged high RPM runs such as what one would experience on the track. For the guys considering something different you must be driving your NSX on the track?.... It's still a darn good piece of kit and the instant torque is my preference for a street driven car.

There's no perfect system for everyone. There's probably just the perfect system for you.

Personally, if I wanted turbo performance i'd get a turbo. Not a centrifugal SC.

 

[davidf]

Theres been plenty of Rotrex systems on the M3 forum. A very popular setup for the M series.

 

[blodi]

I'd love to see a comparison of boost levels through the rpm range between a Rotrex and Paxton/Vortech on the same car/setup. I can't seem to find one, anyone know of one?

 

[DDozier]

I won't argue that its not more efficient than the others just that it works in the same manner. I believe they use smaller compressor wheels but gear them up more to flow more air similar to turbocharger speeds, at redline of course.

They have not developed the gearbox yet, which I'm sure will cause even more parasitic loss on the drivetrain. Keep in mind the same gearbox could be designed and used on any centrifugal supercharger because they all function the same.

Prior to my Aerocharger Twin build I looked at the Rotex as an option to meet my FI needs, the biggest advantage the Rotex has over other centrifugal blowers is the clutch and planetary gear drive system that allows the impeller to free-wheel when not being driven under load. Impeller speeds are tied to RPM when the engine is under load but not on engine decel. This lets the impeller maintain a higher RPM and boost level during rapid throttle changes and act more like a turbo with a BOV than a centrifical blower with a fixed gearing tied to RPM. Other than that it is a centrifical blower like most others.

The gear box idea is an interesting idea but it is one that has some huge hurdles to overcome. Shifting any type of gear drive at those shaft speeds is going to be an issue, as well as an intelligent control method for when to shift.

Dave

 

[L_RAO]

There are some interesting developments with this unit.

http://www.rotrex.com/Home/News.aspx

Read the June 2012 news article, Page 18.

Variable-drive Rotrex units are on their way!