So when I hit throttle, I can feel the turbo kick in and the electronic gauge increases in psi.

What does that mean? Its obviously telling me how much of the charged turbo im using? Is 0.5 slower than 1.0?

Just questions about turbos in general.

Thanks

 

I'm sure you are new in the turbo world.
for sure .5 is slower than 1 bar

 

Yes rather new!

I understand the top level of how turbos work, but not really familiar.

I remember in my friend's Cayenne turbo, he had a gauge that showed a certain amount of turbo available, then decreased as he hit the throttle. Is there nothing similar in the 997 turbo?
Also, how do I know when the turbo is charged up and ready?

 

First of all, welcome to the site.
Second in your dash there is a bar show you how much is the boost, if you have Crono package so in the sport mod you can reach 1.2 bar.
the turbo will start to kick around 2600 RPM if i'm not mistaken (please correct me)

 

the gauge number indicates the amount of boost requested by the ecu, your actual boost may differ.

 

I remember in my friend's Cayenne turbo, he had a gauge that showed a certain amount of turbo available, then decreased as he hit the throttle.

This sounds more like a vacuum gauge than a boost gauge.

 

As I understand it a supercharger is on the intake side of the combustion chamber and "pumps" a fuel/air charge into the combustion chamber. The turbo charger is on the exhaust side of the combustion chamber and "sucks" a fuel/air charge into the combustion chamber.

The turbo charger is activated by the exhaust gases passing through it, so it is always "spinning" to some extent. When you accelerate more exhaust gases are created and the turbo charger spins faster thus sucking in a larger fuel/air charge. This is called "spooling up". Porsche has in its' Sport Chrono package come up with a way to speed up this "spooling up" process and in fact increasing the fuel/air charge.

And that is the extent of my meager knowledge of the subject.

 

thanks guys!

What is turbo overboost? I know im getting more turbo, but what does that really mean?
Also, is the stopwatch on the dashboard, it is always illuminated? Mine is always lit up, even when not in use.
In my cayman, it only lit up when I went into stopwatch mode via the computer (stalk). Otherwise it was not lit up.

 

Read the owners manual. You'd probably enjoy the car more if you read it.

 

bobby,Read it back to back man!!

No info on whether the stopwatch remains lit all the time or not.
Also, not much info on overboost. Just that it provides 0.2 bar more for 10 seconds between 2100 and 4000.

 

it is apparent that you are very new to the world of forced induction, and the mechanics involved in it.

A simple explanation of how a turbo works and abit of common sense and physics would give u an idea to work with. Both a turbo and a Supercharger enhance engine performance by inducing high pressure air into the combustion chamber to enhance efficiency and give u a more potent bang within the cylinder (more air = better fuel combustion... pressurise that within a cylinder and u get a more powerful bank as well), hence the name Forced Induction. However the way in which a turbo and a supercharger differ is how they create the said pressure.
As far as im aware of, and simply put, a Turbo is more efficient at this than a supercharger as is does not use engine load to create boost. It works by having the exhaust pipe pass through a turbine (hence the name turbo), which works as a some-what air-powered compressor (air being disposed exhaust emissions); therefore the more air passing through the turbine the more air pressure it is able to create. spooling occurs quickly once the turbo starts to work and force more are into the cylinders thus as a result more pressurised exhaust emission come through the turbines again, which in turn allows for more pressure to be created, thats when the turbo spools up and and boost suddenly shoots up. However the down side to this is when idling the turbine is not getting enough exhuast flow to allow it to start the chain of pressure creation, but once it starts its good to go from there, this delay is the downside of a turbo, which is named turbo Lag, u can test this in ur car by hitting the throttle from idle and u will notice that the it does not suddenly go fast untill the turbos start spooling. The bigger the turbos (turbines), the more effort they require in order to spool, however bigger turbines are able to generate more pressure just like bigger windmills are able to generate more power, hence two smaller turbos (twin turbos) are used instead of 1 big turbo to achieve the same boost while requiring less time and effort to spool up.
Superchargers on the other hand work by using the engine power to compress air and induce it into the chamber. This is more like a conventional compressor, requiring a belt from the engine to work the compressor. The positive side to this is that it gives near instant boost, no need to spool. However the down side is that it uses some of the engine power to work the compressor hence its not as efficient as the turbo, which is uses waste exhaust. Moreover in a Turbo, higher boost maybe reached at lower revs, as it is concerned with the exhaust air pressure ( the higher is it the more boost u will be able to generate, and once the turbo starts it will take care of that on its own), however in a supercharger, pressure generation is stable with engine revs, the higher the revs the more it can generate, so it goes up with the revs.
The whiny sound in a superchared car is the mechanically driven compressor working, and in a turbo car u can notice the turbine noise as it spools (at least in a 997TT u do :P)

Car manufacturers including porsche have been seeking to reduce the problems with turbos, and at the forefront is turbo lag, and loss of boost betwee shifts. Porsche has developed the Variable Turbine Geometry in the 997TT in order to lower turbo lag by placing valves that reroute air when there is low pressure running through the turbines , allowing them to keep spinning at a somewhat higher speed than what it would during idling, however it does not eliminate it.

I hope this isnt too complicated to understand, and gives u a brief idea of how it works, although this is only a brief explanation, and there other variables involved in the process.

Here is a very good and simple explanation of how it works : [media]http://www.youtube.com/watch?v=Xp-EVOPBhIo[/media]

 

Thanks a lot Dubai!

Any idea about the lit up stopwatch on the dash board?

 

u must have left the stopwatch on.... just reset it and it should go off ... the light does not remain on when the stopwatch is off... should be exactly the same as ur cayman

 

am i missing something? I thought the dash only had (from left to right)
oil temp, speedo, tacho, engine temp/gas, and oil pressure...

Did I miss something or did i just not order the "full package"... i've got the sports chrono, with the super cool stopwatch on the dash.

Thanks.

 

in the speedo there is a bar show yo how much is the boost