Turbo's and Super Charger's.

[Docsamty]

Hi, guys. Fistly I would like to say that I dont have any intention of turboing my sax. Im just keen to learn.

So I understand that the turbo is a device, which gets driven off of a turbine, which inturn gets driven round by exhaust gases. this causes the turbo to 'suck in air' which is pressurised to drive the engine. When it reaches the boost limit (PSI, or BAR) it blows off the air via a wastegate.

Is this correct? Also, is a wastegate the same as dump valve?

My next query, is superchargers which produce lower to mid power as opposed to the turbo's top end power, get driven off of the engine rather than exhaust gases.

Is this correct? and What in the engine drives them?

Finally why do you usually require an intercooler with turbo's? And what are the benefits of front mounting it, like in some perfor manceSupra's for example.

Thanks for any input, Sam.:wink:

[Ryan]

intercooler is needed due to the fact cooler gas = better combustion.

ill reply with the rest 2mo if i have time

[Furio_Matt]

Pretty much sums it up. An intercooler is needed because pressurising the air causes it to heat up and become less dense. Cooler more dense air means more power...hence the intercooler. Reason for front mounting is is rather obvious xD

Edit: Beaten to it -.-`

[Docsamty]

ok thanks, and yes please Ryan.:A:

[col101]

My next query, is superchargers which produce lower to mid power as opposed to the turbo's top end power, get driven off of the engine rather than exhaust gases.

Is this correct? and What in the engine drives them?
It's not so much that the charger delivers lower to mid. It'll deliver good gains throughout the rev range, where as the turbo requires a certain amount of exhaust gas going through it before it'll spin up.
Chargers are run off an extended bottom pulley via a belt to the charger. More boost can be run by using a smaller pulley.

[Docsamty]

This brings me on to another question? If a turbo is kept at a constant boost, via use of a wastegate. How does a supercharger keep constant boost without ever increasing the engine revs, until it blows up? Do these have a wastegate? Or is this where something called a rev limiter comes into play?

[Quick]

Try http://en.wikipedia.org/wiki/Turbo for some reading to start you off.

[saxmad88]

People put restrictor plates on the superchargers so less air can be 'sucked' in.

As said above when the air becomes compressed it will become hotter and therefore less dense. Also because of the massive heat gains in a turbo setup the air will become hotter.

A wastegate regulates the pressure via a spring (inside the wastegate) and a vaccum pips coming from the snail of the turbo. It opens a lets say 'trap door' on the exhaust side of the turbo, which lets air out and into the downpipe. With the use of an electronic boost controller, a solinoid is used to manipulate the pressure to the wastegate, thus creating more boost.

As said above superchargers are driven off a belt and auxilary pulley from the engine (crank usually) As the revs of the engine increase the revolutions of the supercharger increase, this gives a much more linear power delivery (no real lag) and therefore gives a smoother power curve, unlike a turbo that will need a certain amount of revolutions to give good gains, This is what gives you that kick feel in a turbo car.

And the benifits from a front mount intercooler, direct air flow through the cores of the ic, and the air would be cooler. unlike say a top mount where you would have radiant engine bay heat.

[yr51ocw]

it should be noted that top mount intercoolers are sometimes used on OEM applications due to shorter pipework. The more pipe work the more apparent any turbo lag becomes, due to a larger volume of pipe work that needs to be pressureised.

The same princile applies to a intercooler that is too large for its appliction.

[Docsamty]

So if a turbo is a device for sucking in air, do you still require an air filter, or induction kit aswell?

[dannygti]

So if a turbo is a device for sucking in air, do you still require an air filter, or induction kit aswell?

yes......a big one :y:

[Ryan]

So if a turbo is a device for sucking in air, do you still require an air filter, or induction kit aswell?

unless you want a rogered turbine very quickly then you deffinately need some form of filtration system.

[liam-o]

the air filter serves no other purpose than filtering air, the air filter casing directs the air to the engine

cool air = more dense = more oxygen
hot air = less dense = less oxygen

you should read up on air filters separately for them, but the reason for having large front mounted ones is to get as much air as is needed (and front because as your moving the air is forced in and is cooler outside) if its sucking air from the engine bay, its going to be hot air

[Docsamty]

Sorry, It appears that I phrased my question wrong. What I meant is, does the filter go direct to the turbo, and replace the need for a throttle body?

[Ryan]

Sorry, It appears that I phrased my question wrong. What I meant is, does the filter go direct to the turbo, and replace the need for a throttle body?

you allways need a throttle body, else you will have permanenet open throttle.

You run the air filter before the turbo on the inlet system, the pipe from the intercooler then runs to the throttle body.

[yr51ocw]

i appreciate your asking questions to learn, everyone has to learn from somewhere. But most people learn to walk before they can run. asking questions like:

does the filter go direct to the turbo, and replace the need for a throttle body?

shows you have very little knowledge of how an SI engine works, you should read up on the basics of an otto cylce engine before asking about forced induction. This will enable you to take your learning onto a higher level, with greater understanding of the complicated physics involved