How exactly does boost work? Like when does it kick in only when u floor it or...?

 

depends what application youre talking about. you have turbos/centrifugal superchargers & positive displacement blowers (roots/twinscrew) that build boost differently.

 

how exactly does it work? Ill tell, in order for gassoline to burn you need oxygen ( every thing needs oxygen to burn) usually cars ar set up with about 13:1 fuel air ratio. that means the amount of fuel your car can burn depends on how much oxygen it takes in. boost (superchargers and turbos) compress air so that it is more dense. more air=more fuel can be burnt= more power. nitrouse does the same thing, nitrouse oxide has 2 oxygen molicules in it and these come away from the nitrogen molicule some time durring compression freeing up two more oxygen mollicules again more air=more power.

super chargers come in two different catagorys, centrifugal and positive displacement. centrifugal type compress air by flinging it out wards, basicly they use centrifugal force (physics stuff) to get the air to compress. these types useually operate at crazy rpm's to get the job done and dont really make boost untill a certan rpm, they also have a 'peak' rpm which is where they operate most efficiently which is where the concept of turbos came about.
possitive type are like the kenneth bell type. they work by displaceing the air, squeezzing it. they build boost more quickly and more evenly through the engines rpm band, similar to a turbo once it has spooled up.

turbos are really a hybrid beast. they use a turbine which is spun by your exaust. this turns the compressor wich is ussually a centrifugal type. the compressor operates the same as the centrifugal supercharger except if your turbo kit utilizes a waste gate and turbo timer the supercharger will stay at a certan rpm all the time, even as the engine revs from 1k to redline useing inertia (another physics thingy) to keep it going. the more inertia the harder it is to stop and accellerate the turbo which becomes a double edged sword. lots of inertia in the turbo means it will take longer to spool up to little and it will have trouble staying spooled. hope I helped, P.S. type in 'turbos' on how stuff works.com and usually they have nice little animations that help you understand the concept.

 

BTW, turbo is short for turbo supercharger. They are very similar to centrifugal superchargers except they go another step up the efficiency ladder and remove the parasitic drag of a belt and scavenge the escaping exhaust gasses to do the dirty work.

 

I run a Vortech Supercharger. In simple terms, it compresses air and forces it down your engines throat. It makes your engine thirsty for fuel. This is why Supercharged engines require larger injectors and MAFs. More air needs more fuel and that effect gives more power.

On my Vortech, boost kicks in when I floor it. Once the RPMs go over 3000 or so, boost begins and increases with RPM.


When you are driving normally, boost will not kick in.