<center><img src="http://www.autoreview.ru/upload/news/tfsi_1.jpg"></center><p>290 hp, 420 Nm of torque.

Jarod.

though I know little about SC's. From my understanding roots blowers are low efficiency, especially at higher boost levels due to the actual compression happening upstream of the blower, ie. in the intake tract. Other blowers (and turbos) compress partially or mostly in the compressor housing.

Note peak hp and tq at same rpm (4850)... I'll bet there's much more available up top which we'll see in the S4 application (350hp according to rumour).

sure why supercharger won over Turbo... it could be for cost/warranty/modding issues

Twin screw and roots is the same.

Jarod.<ul><li><a href="http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Superchargers/TVS/index.htm">http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Superchargers/TVS/index.htm</a</li></ul>

"Unlike the Roots type supercharger, the twin-screw exhibits ..."

http://en.wikipedia.org/wiki/Twin-screw_type_supercharger

No more pulling the engine to switch out the turbos :P

is considered a "compressor." Screw-type superchargers have an internal compression ratio, which is what makes them different from roots-type superchargers. Screw compressors are also much more expensive, so something tells me Audi would avoid using them.

I have heard figures that up to 40% of the engines output is used to drive the SC, about 4% for turbo cars, and that is only if they show backpressure in exhaust.

will draw around 70hp from the engine while under max boost (and less than 5hp when crusing.) My car came from the factory with 300hp, so that loss equals about 23% of the engines original output. That does not bother me though, since the supercharger will add around 150hp (on top of that 70hp loss.) A proper setup should not reduce the engines lifespan by any great amount. An overtensioned belt setup could cause an early main bearing failure though.

The whole fuel economy of S/C vs. Turbos is getting closer these days as alot of companies use bypasses and disengaging mechanisms(edit: look at VW twincharged motors) to have the blower essentially free wheel when not in use thereby draining a grand total of 0% of the engines power(theoretically) it is still somewhat of an intake restriction tho.

Audi probably is using a Lysholm screw type charger as they are more efficient at higher RPMs and arent just glorified fans. The supercharger will make tunning easier as it will just require swapping out pulleys and an ecu remap, unfortunatley simply adding a new pulley can royally **** up your power band.

Personally i'm loving this whole supercharged motor thing because i have a vision of a twincharged mod which is way easier to do starting out with the supercharger and mating the turbos, i would want to change the S/C to a strait up roots blower though...

lastly blowers are a bit wierd as they often make more power with less reported "boost" because often the boost is a result of back pressure which causes the whole system(S/C and engine) to work harder therby putting less air into the motor so minimizing back pressure(not maximizing boost) is key to S/C performance.

--sorry for the long post guys--