Are you serious with that comment?
1/3 Hp is when you are cruising off boost. With all your car knowledge you think it makes sense that a twin screw producing 15 psi is drawing 1/3 of a HP? LOL... we'd have found the answer to all the world's energy problems.
I don't know what the exact numbers are but at full boost the drag on a twin screw may be costing 50+ HP EASY.
I don't have much knowledge base on the twin screw ones since the one that is on my GTO is a Roots 3-lobe type (the more efficient 4-lobe type that made less heat like the twin screw blowers wasn't out at the time).
Here's a quote from Maggie's site (and I was off by 5mph): "• "Internal bypass valve" virtually eliminates parasitic loss...and delivers a proven 30 to 66% increase in real world "under the curve" power. Best of all, it costs less than 1/3 of a horse at 60 mph. Now that's real efficiency."
http://www.magnacharger.com/sc-gto.htm
Thanks to that, I'm getting 30~MPGs after a good tune at cruising freeway speeds at 65MPH. Of course when I boost the car then the story is more like 10 MPGs. My combined city and freeway driving with me flogging the pedal at every stop light (since the power and sound is like a dam drug) is just over 20 MPGs. Too bad the NSX is a transverse mount engine, otherwise there would be alot of LSx conversions (massive power when needed while sipping gas when cruising).
On Kenne Bell's site here are their efficiency claims:
"30% less parasitic loss and 30% lower air charge temp at same HP."
"More power, cooler charge temp, less power consumption/parasitic loss than stock Eaton."
I'm curious if the Kenne Bell Twin Screw has an internal bypass valve.
The rotary screw compressor has low leakage levels and low parasitic losses vs. roots-type. The supercharger is typically driven directly from the engine's crankshaft via a belt or gear drive. Unlike the Roots type supercharger, the twin-screw exhibits internal compression which is the ability of the device to compress air "within" the housing as it is moved through the device instead of relying upon resistance to flow downstream of the discharge to establish an increase of pressure.
Twin Screw Positive Points:
1) Great Power at Low RPMs (Great for Towing)
3) Factory Fit & Appearance
4) Great Reliability
Twin Screw Negative Points:
1) The Power Doesn't Keep Climbing in the High RPMs (Power curve is very flat)
2) Challenging To Achieve High Boost Levels or CFMs
Of the three basic supercharger types, the Roots has historically been considered the least fuel efficient. However, recent engineering developments by companies like Magnacharger have resulted in an improved Roots-type supercharger, known as the TVS, which is more efficient than their previous models. Most modern Roots-type superchargers incorporate three-lobe or four-lobe rotors. The latest design, introduced for the Ford Mustang GT500 Super Snake, has four lobes per rotor, enhancing its efficiency through a reduction of pulsations.
The Roots-type supercharger is simple and widely used. It can also be more effective than alternative superchargers at developing positive intake manifold pressure (i.e., above atmospheric pressure) at low engine speeds, making it a popular choice for passenger automobile applications. Peak torque can be achieved by about 2000 rpm.
Roots Positive Points:
1) Boost throughout the entire RPM range, right off of idle
2) Highest Potential for Gain (A must-have for all-out drag racing)
3) Excellent Reliability
4) Great Appearance & Stature (Most common supercharger type for show vehicles)
Roots Negative Points:
1) Sometimes Violent Throttle Response
2) Lower boost ratings at higher RPMs
3) Higher Than Normal Discharge Temperatures
