I am sorry I am going to have to disagree with you here, Martin, ...
I am going to wait for the independent road tests and my own driving experience before I decide which is better. No offence intended, but until then, I am going to take the Audi engineers side on this one.
None taken in the slightest ACE. This is afterall a forum where debate is the essence of learning.
I must first point out the following:
me said:
In short, the quickest way to answer your question is to say this:
No. Supercharged engines do not suffer from lag in the way that a turbocharged engine does.
~~~
So in such cases we can see that turbocharging technology has come a long way (small, twin-turbo'd configurations; twin-scroll turbos) in the interests of reducing lag almost entirely. But, as long as turbo's are spun by exhaust gases - there will always be some small measure of lag.
I most certainly acknowledge that supercharging - especially employing the latest roots-type technology - is more throttle responsive than turbocharging.
However, what I am pointing out is that modern turbocharging has come a long way and that the engine response of turbo'd cars like the MINI Coopers S and, more pertinently, the 335i is massively impressive. I have years upon years of personal acquaintance with turbo'd engines and in my experience the throttle response of the 335i is unbelievable. Surely not better than a new S4 at 2200 rpm and beyond but darn close.
Also, the peak torque of the S4's engine is telling: there is a period of time when the engine is producing less than its peak torque as the supercharger spools to the optimum rpm from low revs. Just like a naturally aspirated car.
What I'm trying to convey is this concept of responsiveness. There are two trains of thought here; the first is where is peak torque created in the rev range - in this case the N54 is superior - and the next is the perception of throttle response i.e. from when the throttle is closed, then fully opened and the time elapse
perceived by the driver between this and the engine "reacting". In the case of the latter the supercharged engine is, without question, more responsive. The problem encountered is that torque figures are always quoted at max throttle openings and this skews the impression of torque availability and hence, engine responsiveness.
Also, we've now seen that the N54 engine is easily good for 245 kW and 440 Nm in the new F01 740i so the output figures are clearly very carefully controlled by electronics and not actual mechanical physics.
It is interesting to note that the Audi engineers (read marketing dept
) have made the comment around the vast superiority of mechanical charging vs turbocharging whilst all the while:
- employing turbocharging in many of their other vehicles
- having turbocharging as a tradition in their stable
- just about every other manufacturer eschewing supercharging for its drawbacks and moving toward turbocharging.
A case of sour grapes that their long time rivals have achieved such considerable success with turbocharging? I'm speculating. But it is fun!
But ja, can't really disagree with you.
I mean the superchargers hooked up to the V8 in the SLR can't be eating 80-120hp or so, no?
I'd like that too, but we need to ask Martin first and if he accepts, i don't think Mark (admin) would hesitate to do so.
