Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site emacs.UUCP Path: utzoo!linus!decvax!cca!emacs!pz From: pz@emacs.UUCP (Paul Czarnecki) Newsgroups: net.auto.tech Subject: Theory of Turbos Message-ID: <2@emacs.UUCP> Date: Wed, 1-Jan-86 16:54:44 EST Article-I.D.: emacs.2 Posted: Wed Jan 1 16:54:44 1986 Date-Received: Fri, 3-Jan-86 03:17:12 EST Distribution: net Organization: Uniworks Inc., Wellesley, MA Lines: 52 I have a question about the functioning of turbo and super chargers. First, be warned! The early part of this article contains factual errors, do not skim it and then flame me saying "You're wrong!", I know I am, that is why I want the answers. Both turbos and supers compress air and put it inside of the engine. The reason why you do this is that you need more oxygen to burn in addition to more fuel. A super charger is mechanically coupled to the engine. If the engine is turning a x rpm then the super charger is turning at sc(x) where sc() is linear. The same is not true of turbos. The turbo is fluidly coupled (air is a fluid) to the engine. I had thought that `if the engine is turning at x rpm then the turbo is turning at tc(x) where tc() is a linear function ONLY AT TIME t sub zero after the engine reaches x rpm.' This is the source of turbo lag. The turbo must `catch up' to the engine. Well my boss let me drive his car (Saab 900 Turbo w/16 valves and APC, btw, this is a nice car (too bad it's been broken into twice in the past year)) the other day and it became obvious that the above is not true. Take the case where you are charging down the road at 4,000 rpm and you let up on the throttle without depressing the clutch. Under the above theory the turbo would continue spinning at tc(4000) since the engine is still at 4,000 rpm. However the boost guage indicated an IMMEDIATE drop in boost. QUESTION: why is this so? Any takers? (super charger trivia -- back in the 50's a lot of MG owners put superchargers on their cars. Name the city that made (most) of these and name at least one other metal sporting good part that this city made. hint: it's near my hometown :-) pZ -- -- My wife ran off with my best friend, and I miss him. Paul Czarnecki Uniworks, Inc. decvax!{cca,wanginst!infinet}!emacs!pz 20 William Street emacs!pz@cca-unix.ARPA Wellesley, MA 02181 (617) 235-2600