Supercharger
11-05-2007, 04:02 PM
#2
3rd Gear Member
Join Date: Oct 2006
Location: Ohio
Posts: 889
RE: Supercharger
Twin screw = boost from lower RPM. high effiiciency (great power for PSI), quieter, more expensive. Twins are KB, Whipple, and Saleen.
Centrifugal = build boost more mid range and top end, less expensive. Not as versed in these but itseems like a lot of guys have Vortech, Paxtons, and Prochargers.
For a street car, I'd rather have (and do have) the screw. No wrong choice though.
Centrifugal = build boost more mid range and top end, less expensive. Not as versed in these but itseems like a lot of guys have Vortech, Paxtons, and Prochargers.
For a street car, I'd rather have (and do have) the screw. No wrong choice though.
11-05-2007, 04:23 PM
#5
2nd Gear Member
Join Date: Feb 2007
Location:
Posts: 162
RE: Supercharger
This is a very opionated topic because there is no wrong answer. I personally would go with the centri because I feel you dont need to be in boost all the time. For one thats more gas being burned and at part throttle theres just no need to be in the boost. Also when it comes to adjustability if you were to build a motor later on its easy to push a lot of boost out of a centri and turn up big numbers. But like I said its all opionated and any kind of power adder will be a great time.
11-05-2007, 04:38 PM
#6
6th Gear Member
Join Date: Sep 2006
Location: Gainesville, FL
Posts: 11,278
RE: Supercharger
ORIGINAL: iwannagofast
This is a very opionated topic because there is no wrong answer. I personally would go with the centri because I feel you dont need to be in boost all the time. For one thats more gas being burned and at part throttle theres just no need to be in the boost. Also when it comes to adjustability if you were to build a motor later on its easy to push a lot of boost out of a centri and turn up big numbers. But like I said its all opionated and any kind of power adder will be a great time.
This is a very opionated topic because there is no wrong answer. I personally would go with the centri because I feel you dont need to be in boost all the time. For one thats more gas being burned and at part throttle theres just no need to be in the boost. Also when it comes to adjustability if you were to build a motor later on its easy to push a lot of boost out of a centri and turn up big numbers. But like I said its all opionated and any kind of power adder will be a great time.
11-05-2007, 04:39 PM
#7
3rd Gear Member
Join Date: Oct 2006
Location: Ohio
Posts: 889
RE: Supercharger
ORIGINAL: iwannagofast
This is a very opionated topic because there is no wrong answer. I personally would go with the centri because I feel you dont need to be in boost all the time. For one thats more gas being burned and at part throttle theres just no need to be in the boost. Also when it comes to adjustability if you were to build a motor later on its easy to push a lot of boost out of a centri and turn up big numbers. But like I said its all opionated and any kind of power adder will be a great time.
This is a very opionated topic because there is no wrong answer. I personally would go with the centri because I feel you dont need to be in boost all the time. For one thats more gas being burned and at part throttle theres just no need to be in the boost. Also when it comes to adjustability if you were to build a motor later on its easy to push a lot of boost out of a centri and turn up big numbers. But like I said its all opionated and any kind of power adder will be a great time.
I average 22 mpg on the highway even with the 4.10s.
11-05-2007, 04:41 PM
#8
2nd Gear Member
Join Date: Feb 2007
Location:
Posts: 162
RE: Supercharger
Do you have a blow off valve that releases it? I havent really gotten a chance to look into the newer supercharger packages so I very well could be wrong. But youve gotta love the whine of a centri.
11-05-2007, 04:56 PM
#10
4th Gear Member
Join Date: Jul 2007
Location:
Posts: 1,062
RE: Supercharger
Twin screws do not build boost all the time. Centris do. The boost may not make it to the engine, but due to the placement of the throttle, Centri's will produce boost at part throttle/high RPM that gets dumped to the suction.
A centrifugal supercharger produces a suction at the inlet based on RPM. The higher the RPM, the more suction it produces, and the more air it compresses. If your throttle is open only part way, the compressor is still using engine power to compress air, but it is being bypassed back to the suction side of the compressor, via a surge controller. Surge is when a centrifugal or axial compressor's flow goes backwards due to the discharge pressure being to high, flow rate to low. This reversal in flow happens many times a second when surge line is reached. A bypass valve allows the compressor to discharge and maintain a flow/pressure curve above the surge line. So when you are part throttle and high RPM, the Centri supercharger uses power to create boost that is being dumped back to the suction line. Full thottle, the bypass valve closes, and the pressurized air goes to the engine.
Twin screw is positive displacement, with the throttle valve on the inlet. This is called inlet pressure control, and is more efficient. During part throttle, less air is fed to the supercharger then it can handle (volumetric eff. is way down) so it takes very little power to turn the compressor, regardless of RPM. Part throttle, high RPM with a TS potentially uses less power then the Centri, because not only are you limiting the air flow to the compressor, they also have a bypass which dumps the discharge back to the suction line. If the throttle was placed after a twin screw compressor, it would become less efficient then the centri at part throttle/low RPM because of its positive displacement.
A centrifugal supercharger produces a suction at the inlet based on RPM. The higher the RPM, the more suction it produces, and the more air it compresses. If your throttle is open only part way, the compressor is still using engine power to compress air, but it is being bypassed back to the suction side of the compressor, via a surge controller. Surge is when a centrifugal or axial compressor's flow goes backwards due to the discharge pressure being to high, flow rate to low. This reversal in flow happens many times a second when surge line is reached. A bypass valve allows the compressor to discharge and maintain a flow/pressure curve above the surge line. So when you are part throttle and high RPM, the Centri supercharger uses power to create boost that is being dumped back to the suction line. Full thottle, the bypass valve closes, and the pressurized air goes to the engine.
Twin screw is positive displacement, with the throttle valve on the inlet. This is called inlet pressure control, and is more efficient. During part throttle, less air is fed to the supercharger then it can handle (volumetric eff. is way down) so it takes very little power to turn the compressor, regardless of RPM. Part throttle, high RPM with a TS potentially uses less power then the Centri, because not only are you limiting the air flow to the compressor, they also have a bypass which dumps the discharge back to the suction line. If the throttle was placed after a twin screw compressor, it would become less efficient then the centri at part throttle/low RPM because of its positive displacement.