Quote:
Originally Posted by garagelogic
If you think screws are "all hype", then you really need to do some more research. Here is a graph of the KB on my car:
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This is on my 331cid engine and pushing ~12.5lbs of boost. Torque drop off on the big end is minimal and if you notice, the HP was still climbing when I let out of it at 6250. Those curves are quote a bit different than these:
What you don't see is the amount of heat being generated. The TVS (Roots) is going to produce a greater charge temperature per pound of boost than the twin screw. If you configured both blowers to produce 20lbs of boost, the TVS would proably see about 18,000rpm and a discharge temp of about 340 degrees whereas the twin screw would only need about 12,700 to produce the same 20lbs of boost and have discharge temps somewhere around 282 degrees.
Not only does the twin screw incur less parasitic loss (about 147hp is need to turn the TVS at 20lbs vs. the twin screw's 110hp) but it requires less rpm to do it with a significantly reduced inlet temperature. These are pretty much guesses on my part, but I think if you did a comparison of the two, the data would hold up for the most part. |
I need to do my research?
What are your discharge temps at 12 psi with that bell blower?? Spinning a 2300 in exess of 25K + RPM we never saw temperatures above 40* over ambient. In other words on a 100* day the discharge temps were 140 * +/- 10*. That being said, at 8 psi on my 1900 I NEVER see anything over 25-30* ambient.
As for the parasitic loss, if you can explain to me how you are able to unload the screw and make it as efficient at the Maguson @ highway speeds it would be great. A screw compressor by definition is a COMPRESSOR and is ALWAYS compressing. There is NO way it can be bypassed and there is no way it can possibly be cooler due to the simple fact that is always compressing the air.
As for your comment about a comparison, I would LOVE to do that. I have the engine, the dyno cell and the staff.....Bring the blower, the magazines and the beer and I am game.