I test the new Audi RS4...

[Verrückt]

Road Test

Engine Revving

Acceleration 1

Acceleration 2

Acceleration 3

[Alcora]

I like it but the sound is too soft and quiet...

[RabidPony]

I think it sounds pretty badass on the outside. It is kinda quiet inside but what do you expect from a luxury/performance car?

[Bellamacchina]

Error!!!!

[Darkness]

I like it and the performance is there. But I was reading on the piston speed and its wayyyy past the reliable speeds in all the engineering books and classes that I took. I mean seriously the piston speed on that car when its past 6500rpms is just too great for long term reliability. Those piston rings and cylinder sleeves are going to need replacement in less than 50.000 miles.

Here's a simple chart that examples that. The Audi's piston speed is 25.7m/sec which in Ft/min is 5088ft/min.
Mean Piston Speed Result
------------------ ------
Under 3,500 ft/min Good reliability
3,500-4,000 ft/min Stressful, needs good design
Over 4,000 ft/min Very short life

Draw your own conclusions on it. Nice car though!

[Verrückt]

Originally Posted by Darkness

I like it and the performance is there. But I was reading on the piston speed and its wayyyy past the reliable speeds in all the engineering books and classes that I took. I mean seriously the piston speed on that car when its past 6500rpms is just too great for long term reliability. Those piston rings and cylinder sleeves are going to need replacement in less than 50.000 miles.

Here's a simple chart that examples that. The Audi's piston speed is 25.7m/sec which in Ft/min is 5088ft/min.
Mean Piston Speed Result
------------------ ------
Under 3,500 ft/min Good reliability
3,500-4,000 ft/min Stressful, needs good design
Over 4,000 ft/min Very short life

Draw your own conclusions on it. Nice car though!

Those numbers are somewhat old. Technology has advanced so the envelope can be pushed more, but I agree with you. I think it's too much...which is somewhat why I made such a big point about it in the article.

It's my personal opinion that the engine will have problems.

[Darkness]

Originally Posted by Verrückt

Those numbers are somewhat old. Technology has advanced so the envelope can be pushed more, but I agree with you. I think it's too much...which is somewhat why I made such a big point about it in the article.

It's my personal opinion that the engine will have problems.

The technology is basically putting better piston rings. ie thicker and better material. But there's not a whole lot that can be done, friction is still going to be there and thats what's going to kill it. I guess we'll just have to see what happens in the long term.

[Verrückt]

Originally Posted by Darkness

The technology is basically putting better piston rings. ie thicker and better material. But there's not a whole lot that can be done, friction is still going to be there and thats what's going to kill it. I guess we'll just have to see what happens in the long term.

Not really. The trend is to use thinner rings (made of stronger materials) with lower tangential loads to reduce friction and increase conformability.

At those speeds, I'd be concerned about the stability of the rings, the bearing loads, and the fatigue on the reciprocating parts.

[Real1ty]

Nice, the RS4 is a monster, I love the sound by the way.

[Tarmangani]

Audi A4/S4 as luxury car ? It's a joke ?

[Gilly]

Clarkson was testing this on Top Gear last weekend and he couldn't say enough good things about it, and even went as far to say he thinks he was sitting behind one of the best engines ever made and even the new M3 will need to come with a free moon to be better :lol:

I'd certainly have 1

[Verrückt]

Originally Posted by Gilly

Clarkson was testing this on Top Gear last weekend and he couldn't say enough good things about it, and even went as far to say he thinks he was sitting behind one of the best engines ever made and even the new M3 will need to come with a free moon to be better :lol:

I'd certainly have 1

Personally I think he gushed a little too much about the car.

[Darkness]

Originally Posted by Verrückt

Personally I think he gushed a little too much about the car.

Yeah if it was Jeremy that talked about it, then it must've been biased. I like the car and to tell you the truth I wish I had bought the S4 instead of the A6 I now have. But oh well, its the commuter, not the playing car.

[ski84cas]

looks like it's kinda quick from 30 to 90 :thumb: but no top end acel.:mecry:

[Verrückt]

Originally Posted by ski84cas

looks like it's kinda quick from 30 to 90 :thumb: but no top end acel.:mecry:

The speedometer slows down after 100 because the difference between the numbers changes.