19Hawkins86

Hello,

i thought that the essential advantages of a supercharger are the throttle response an the higher boost at low rpm.

But when i look at the technical specifications of e.g the TT-RS, we have 450nm at 1600rpm, the S4 has 440nm at 2900rpm.

Can anybody explain that?

Please excuse my poor english

Aggie88

I am not familiar with these 2 engines. Are they both four cylinders or six? Which engine is larger displacement? Don't forget, Audi's philoshophy (and many other MFRs) is to use smaller engines and forced induction to achieve equivalent power but less fuel consumption. So the SC version of the same car may have an engine with lower power output than a normal apirated engine with larger displacement.

For example, for the Q7, the outgoing engine is a 4.2 V8 normal aspirated with 350 hp, and the new SC engine is 3.0 V6 with 330 hp. But the torque output is same at 350 lb-ft. Quite impressive for six cylinders.

19Hawkins86

The TTRS has a turbocharged 5-Cylinder ,the S4 a supercharged V6, but with 450nm at 1600rpm the RS has higher boost at low rpms, so i dont unterstand why audi decided to put that SC on instead of a TC.

Aggie88

Good point - it may be simply consolidation of engine varieties to reduce costs - unfortunately.

volsfan0911

The big advantage of a blower (supercharger) is responsiveness. Turbos are exhaust gas driven and even the best designs (BMW dual scrolls, very small quick spooling as in my VW GTI, etc.) still have some lag between hitting the throttle and boost coming on. Since the supercharger is literally connected with the engine via an actual belt there is no lag. The best of both breeds have gotten so good it's amazing but any turbo motor is going to have some delay coming off idle before you're up to full pressure. That's why you see drag cars with blowers rather than turbos. Some car mags also credited the Audi engineers wanting to 'try something new' and seeing what they could do with supercharging versus the typical turbo setup. I think they came up with a very well done product and it definitely works as a fantastic motor IMHO.

volsfan0911

Sorry - meant to add above. Blowers also can have a packaging advantage - since it's living in the V of the engine, it takes up less room under hood and doesn't generate the heat load that a turbo would. Less engine compartment heat makes makes a difference. BMW with the N54 had several instances reported on their forums of owners under hard driving or extreme environmental conditions overheat their cars necessitating the use of an additional oil/air heat exchanger. More plumbing, more cost, greater complexity, one more thing to go wrong.

dtmurf

Drove the 3.0 V6T in a S5 Sportback this afternoon…all in all a Very impressive engine

Jay Christianson

volsfan0911 has a solid point - Turbos add complexity while, relatively speaking, superchargers keep that to a minimum. Heck I have a TRD supercharger on my old 4Runner that took a couple of hours to install, and is a fully sealed unit with 100K mile warrantee. Turbos on the other hand usually require oil from the engine oil system, and with the high heat they can degrade the oil for the whole car, but of course the first point of failure will then be the turbo as it is operating at super high RPM. The flip side of course is that the supercharger is not as efficient as the turbo as it is leeching power from the engine.

Either way I am a supercharger person.

Dino757

Straight up.... I miss the low end torque of twin turbos. A 3.5 ecoboost makes 350-420 lb/ft of torque from 1700-5500 rpms (depending on the application). In real world driving, it's much more satisfying. My 3.0 is fun to drive, but the eco's have effortless driveability. Like a diesel, the torque is always present. Comparatively, a 3.0 is more like a motorcycle. ring ding ding ding. There's no hiding the fact that you're trying to go fast.