| e39_touring |
02-17-2023 03:44 PM |
Quote:
Originally Posted by Happy
(Post 1227648)
Over the years, I have come in contact with some very reputable BMW aftermarket engineers / tuners who have taken time to take a quick glance at OLe’GiRL. And one of the discussions that I was quick to elude to was, should I have gone with the “other” blower. And the quick response was always, No!
The Vortech supercharger fitted to the M54B30 was always the suggested choice. I can’t tell you how many times I have read that ESS blower description LoL.. But what I can tell you is, there is some nonsense in there. The main quarrel I have with it is, the statement that a centrifugal blower is only capable of 1 lb of boost at 2200 rpm. By 2200 to 2500 rpm I am already making 5 - 6 lbs of boost. That is only 2 lbs shy of the max boost of 8 lbs for the TS2. And, with the pulley I have on there now, I am topping out at nearly 12 lbs of boost. That is half of the total boost above what the TS2 has to offer.
The ESS is directly charged through that custom manifold. However, my Vortech is direct charge as well, with a RMS discharge tube of only 4 - 5 inches in length. The blower is damn near connected directly to the throttle body. Believe me when I tell you there is zero parasitic loss.
There were a few choices out there before, definitely not the case today. But after all that I have learned though this process, Vortech V3Si is hands down the best blower in my opinion.
E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21
|
Good discussion, and I think which is better for you depends on what you want out of your setup. Boost is an interesting measure that I think gets misused from time to time. Boost is caused by an excess of airflow over what an engine is ingesting at a given time. So, for example, take two engines of equal displacement, but one with higher volumetric efficiency (better cams, heads, exhaust, etc.) than the other. Add the same power-adder to both engines, and the higher VE engine will produce less boost but make more power, generally speaking.
Now, compare the twin-screw 'squeezer' to the centrifugal 'blower'. The centrifugal is a fan/turbine blowing air at the motor, and as the delta between what the motor requires and what the blower is pushing grows, boost goes up. Airflow pushed by the turbine is not linear to rpm but follows an increasing curve (to a point). That's why they say it 'builds boost in a linear fashion'. Airflow is actually increasing as a function of RPM. Put a big centrifugal blower on there, and you can build a lot of boost at low RPM, but that may lead to too much boost at high RPM.
I called the twin screw a 'squeezer' because it grabs air from the outside and literally squeezes it as the air moves between the ever-decreasing gaps between the rotors as they rotate toward each other. Unlike the turbo/centrifugal blower, it's not really an airflow thing. The twin-screw is delivering pre-squeezed (compressed) air to the motor in direct proportion to RPM. Size the twin-screw blower right, and you'll get exactly the same boost everywhere in the RPM range (less efficiency losses). It has the exact same effect as a larger displacement engine. In reality, though, the twin-screw blower is sized close enough but not exact, and people will change the pulley size to increase or decrease boost similar to a centrifugal blower, which then introduces a little linearity of boost vs. rpm.
For a truck and towing, etc., I prefer the twin-screw as it produces more torque at lower RPM. But for spirited performance driving (like Happy), the centrifugal makes more sense and will have a higher limit of power. |
