Do some vendors/companies not know the difference ...

cdjnight

Drives: ZL1 A6

Join Date: Nov

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Location: Council Bluffs, Iowa

Posts: 266

Drives: ZL1 A6

A twin screw is similar in design, as it has two rotor but the main difference you will notice is the number of lobes on each rotor are different and they draw air in from one end and return it to engine from the other end of the lobes. The reason for this is because the lobes have a tighter clearance as they move from on end to the other (creating pressure before it leaves the supercharger). (Whipple, KenneBell,)

A roots blower typically has a huge parasitic drag on engine by comparison. But newer designs added bypass valves that essentially let them freewheel.

Hope this helps.

Quote:

The company is the world’s best Twin Screw Roots Blower supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

old motorhead

Originally Posted by

One rotor spins faster than the other on the t'screws? You sure about that?

"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."

True roots style blowers pull air in one side draw it around the outside of the lobes and stack it into the intake manifold creating pressure, They're relying on a restriction to create pressure. They also have an equal number of lobes on each rotor. (Eaton, Wiend, B&M, 6-71, 8-71 etc..) The lobes can be straight or twisted(Helix cut)A twin screw is similar in design, as it has two rotor but the main difference you will notice is the number of lobes on each rotor are different and they draw air in from one end and return it to engine from the other end of the lobes. The reason for this is because the lobes have a tighter clearance as they move from on end to the other (creating pressure before it leaves the supercharger). (Whipple, KenneBell,)A roots blower typically has a huge parasitic drag on engine by comparison. But newer designs added bypass valves that essentially let them freewheel.Hope this helps.And Yes a "Twin Screw Blower" turns the lobes at different speeds. It has to because there is a different amount of lobes on each rotor.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."

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Last edited by cdjnight; 03-12- at

11:04 PM

. Reason: added quote from Eaton

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