Do the superchargers work all the time or are they kicked in with 100% throttle or above 90%? And if superchargers are linear forced induction then how can they affect driveability. (12/99)
I don't know about superchargers in general, only the Sebring unit. It has a bypass block. When the throttle is closed the intake is under vacuum and the supercharger is bypassed. It still spins (freely) but the air going to the engine goes past it. Once the throttle starts to open the vacuum goes and the bypass closes so the supercharger is "online". There is a slight surge as this happens, but it really is at very low throttle settings so you go from "not much oomph" to "only a tiny bit more". If you floor the throttle suddenly you can feel it if you're already moving along but I always bleed in throttle so I don't really notice it. Passengers never notice it. (12/99)
After seeing all the supercharger stuff of late I feel in need of alittle more power ready for next summer as I only have a 90bhp 1.6. What sort of power increase will I get if I add a supercharger? Then all I have to do is find the cash. (12/99)

The efficiency of the blower varies with engine speed .. at low speeds it is not generating any boost .. then as speed rises it beats the losses around the blades and so makes boost .. this boost then shuts the by pass valve and increases power. The boost is therefore controlled by the efficiency of the blower and the engine .. put a bigger pulley on the crank feeding the blower (or smaller one on blower) and you will get more boost until you meet the upper efficiency limits of the blower .. at which point less boost can be created.

So there is a bit of engine breathing/efficiency interaction with blower breathing/efficiency .. so it is not totally linear.

At idle and cruising there may be no boost as the vacuum level in the inlet manifold opens the by pass valve .. which incidentally must be set at some level below 0" of vacuum .. funny as turbos can cruise at 0" of vacuum with a slight boost but no real boost .. does this area that the super cannot operate in not cause a non linear part throttle response .. guessing here.. (12/99)
Yes it does. But I think I covered this - it's at such a low throttle setting that it's not really worth bothering with. (12/99)
For anyone wishing to learn more about turbos/superchargers (ie me) I've found this site to be excellent, lots of pictures, http://www.overboost.com/story.asp?id=187 This article explains the basic components of a turbo. Theres also a good article on how to install a S/C on an mx5. (12/00)