Huge argument brewing at work now!
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 2,303
Likes: 40
From: Edmonton Alberta
Huge argument brewing at work now!
The new Edelbrock Supercharger currently being offered for the C6 Corvette to be exact - the discussion: is it a roots style blower or a screw type blower?
Only a bunch of guys, (who should actually be working instead of discussing cars) could build this up to such a frenzy. I'm saying it's a roots and my buddy is saying it's a screw.
Only a bunch of guys, (who should actually be working instead of discussing cars) could build this up to such a frenzy. I'm saying it's a roots and my buddy is saying it's a screw.
Racer
Joined: Dec 2007
Posts: 287
Likes: 10
From: Alamogordo NM
Have your buddy read this, especially the third question from the bottom
http://www.eaton.com/Eaton/ProductsS.../FAQ/index.htm
http://www.eaton.com/Eaton/ProductsS.../FAQ/index.htm
Instructor
Joined: Oct 2009
Posts: 246
Likes: 18
From: Leander TX
Yep its a roots type. I thought it was a screw until ZZMike posted that link!!
Straight from the posted link above...
"Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?'
A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio.
The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns."
Straight from the posted link above...
"Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?'
A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio.
The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns."
Last edited by stivette; Jan 13, 2012 at 09:30 PM. Reason: Add info
