Talk:Twin-screw type supercharger

technical criticisms of this article

"All supercharger types benefit from the use of an intercooler to reduce heat produced during pumping and compression."

While this is accurate it somewhat of an oversimplification. With the adiabatic efficiency of a lysholm (or at least the smaller ones) being in the high 80's to 90%, the benefit of intercooling is not particulary significant. And while ANY internal combustion engine will benefit from a cooler intake charge, a Roots, CSC, or turbo will benefit to a much larger extent. Perhaps this though could be more completely developed in the article. SteveOak25 (talk) 12:51, 7 May 2009 (UTC)

I think the following critique raises good questions. They should be addressed in the main article. Greg Locock (talk) 05:23, 2 May 2008 (UTC)

"Many cold-air kits, exhaust upgrades, and most often any engine upgrade can often be retained when installing an aftermarket twin screw, excepting throttle bodies outside the range of the twin screw's machining. Though Roots-style blowers like the Eaton are effective, even the newer Eaton TVS series supercharger show much less results from porting (what? this is nonsense). The Roots fails to surpass the twin screw (in what way? adiabatic efficiency perhaps but not in others) due to the more controlled nature of the flow between screws (again, nonsense. Internal airflow inside a Roots supercharger is controlled in the same way it is in a twin screw). Imagine trying to paddle a boat with a flat paddle; water goes everywhere, where if you have a twisted and close knit pair of screws you could easily push far more water with far less turbulence to lose power (this is ridicuous: both are positive displacement superchargers, nothing like an oar moving water around in an open circulatory system). However, the Roots is much easier to manufacture (no, simply less expensive), and the twin screw is somewhat more difficult to refine for use (not true). Unlike centrifugals, the same factor which allows the volume based compressor attitudes of the Roots and twin screws undermine their ability to run coolly at idle when boost is not allowed to flow freely into and out of the chambers of the engine. To compensate, blow-off and bypass valves are often installed and provide extreme benefits (not extreme). Surge is eliminated however (no. only when throttle is pre-supercharger), unlike with centrifugal (turbo-based aspiration driven by crank instead of exhaust) superchargers, the two "volume based" compressors work by forcing their volume through per revolution. Reliability is often improved by the lack of extreme heat caused by exhaust that plagues turbos (no, OE turbo applications have proven this for 30 years now), and self-contained twin-screws (carry their own separate and often self-cooled synthetic oil blends, as the motor's oil is often very much hotter than the supercharger (also untrue. where did you get this silly information about temps?)) are about as effective as their self-contained centrifugals ("about as effective"? Not scientific nor based on fact). However, it is far more beneficial to run a centrifugal blower above 25 psi of boost (25+ ambient 14.7psi @ Sea level) (untrue! this should be deleted) due to ease of inter-cooling (ridiculous: it's just as easy to intercool regardless of the configuration of the air pump aka supercharger) and large, often unwieldy, twin screws of proper output would require a lot more than the average engine would be able to supply (again, ridiculous. If you can intercool X amount of air out of one blower you can do it out of another. Please, people, don't write about things outside your realm of expertise. If you aren't professionally employed in that field please think twice before posting). Compression ratios also play key role in power output, a 8:1 compression ratio is about what most serious racers will shoot for, as much lower than 8:1 compression yields rough and hard idle (untrue. idle is very soft and tame; large camshafts affect idle, not compression!), near gutless power output (how scientific), and high compression ratios like 14:1 will be far too hot alone (untrue - look at late model mass production vehicles with 11:1+ ratios), and the supercharger will work as a function to that with boost which will cause absorbent amounts of heat that will (no. "may", not "will") ultimately cause engine knock and failure. Engine knock is also by far more likely to cause engine damage than boost itself, most modern engine components can withstand 12 psi with no modifications, while some models that are factory fitted with a turbo may handle much higher boost "