Twin Charging

[GTR Dreamer]

when twin charging (superchrger+turbo) is it possible to disconect the supercharger?
e.g- if your supercharger runs from 1000rpm to a max of 4000rpm(without burning it out) then when you get to 4000rpm can you disconect the supercharger so you can just run high boost? so that you dont blow up the supercharger? any help is appreciated

[Matra et Alpine]

yes - and I have to add this text to meet the minimum size requirement for UCP

[GTR Dreamer]

thank you, does it just have a little gear that does something?
by the way im talking about screw type s'chargers.
p.s thanks for the quick reply

[Matra et Alpine]

WHich form of supercharger doesn't matter as the main way to engage/disengage them is the same.

With a clutch - now usually electromagnetic - on the input spindle.

Not sure what you're thinking but here's a precise description of the Toyota s/c clutch foudn by a quick google ......
Supercharger Clutch

The supercharger clutch works in the same way as an air conditioning compressor clutch. The pulley itself spins freely on the supercharger-input shaft. A coil of wire sits behind the pulley and a metal disc sits in front. The front disc is connected to the actual input shaft of the supercharger. When the coil is energized, the disc is drawn against the rotating pulley and they then= rotate together as a unit until the coil is de-energized.

The manufacturer intended this clutch to be operated based on intake manifold vacuum. If vacuum drops below 8"Hg the supercharger clutch is engaged. The clutch should stay on until the intake manifold vacuum has risen to over 10"Hg for a period of 5 seconds. This time delay is required to avoid cycling of the clutch during shifts and momentary throttle transitions. A delay circuit is required to replicate this behaviour when fitting these units to other vehicles

The manifold vacuum during highway driving will be low enough that the SC clutch will stay engaged all the time with an appropriate controller circuit of this type

taken from http://homepages.tig.com.au/~ovlov/technical/blower.htm

[KnifeEdge_2K1]

btw anyone have a good diagram of roots superchargers? the crappy diagram from textbooks and internet dont really give the whole story, like screws are easy to picture and understand as are centrifugal type scs (its just half a turbo, which is confusingly just another form of s/c :P)

[Matra et Alpine]

Courtesy of a uk bike site

http://www.thefang.co.uk/superchargers.htm a wee animation to explain PART of it.

[GTR Dreamer]

thanks Matra!

[Smokescreen]

now, from what you just said matra, this also seems possible that i car could have a blower that didnt run all the time, like the new hemi's MDS. match a blower with a clutch, a manual one that could be run whenever,you could go from daily driver milage to 500+ horse, if that would seem possible. i guess compression ratio would make that harder though.

[Matra et Alpine]

i guess compression ratio would make that harder though.

Unless you use Volvo's variable compression head !!!

[paul]

what volvo has the variable compression head in use?

thought saab was only just thinking of using it now?

[KnifeEdge_2K1]

Unless you use Volvo's variable compression head !!!

last time i checked it was saab who had it, when volvo get one?

[paul]

yea but have they actually put it in a car yet? like production, or is it on its way soon?

[Matra et Alpine]

Yeah I meant Saab, but I've seen they won't introduce it coz there are some long term issues The web search to confirm that DID find that theere is a Volvo TD100 research engine which has variable compression, but no song and dance about it.
I guess it's fair to say EVERYOEN is testing it as I also found VW/Audi have one too

[GTR Dreamer]

how does a varible compression head work?

[Ferrari Tifosi]

This site will help 'ya GTR Dreamer with understanding variable compression engines. It explains Saab's SVC engine.

http://www.saabnet.com/tsn/press/000318.html