Dear Friends,

as promised, i would like to say a word or two concerning „Carbon build-up“:

What is “Carbon build-up” and how does it come into being:

With fuel direct injection the cylinder heads and valves are no longer “washed” by fuel, which leads to a lacking “cleaning factor”. This is where the exhaust gas recirculation combined with the ventilation vapor of the crankcase ventilation and oil starts to build up. Particles of dirt and jets of water coming through the air intake path form into firmly adhering layer. This layer is taken up within the chambers of the cylinder heads and the admission valves, resulting in a rough surface, the airflow cross-sections become more narrow leading to non optimal air interlacing and cylinder charge. In total the results of “Carbon build-up” can be bad exhaust emissions, lower power output and higher consumption. In worst case the “Carbon build-up” affects the valve train. The valves can not close completely, which leads to low compression on the relevant cylinder, the fuel composition is not “fired”.

Factors that promote “Carbon build-up”:

Low quality fuel

Frequent short range driving

Preventing higher engine temps

Low RPM driving

intermittent driving

long time „not-using“

using non-specific engine oil


Audi RS 5 and „Carbon build-up“, do i have to worry?

As you might already know, the RS 5 engine ist based on the RS 4 V8 version. Main “Carbon build-up” relevant points that have been altered:

Engine production tolerance over again significant improved

Engine oil temp is increased by ~10°C

Modified piston rings


Resume:

The probability of „Carbon build-up“ within the RS 5 engine is nominal.

Qisha

PS: as the RS 4 V8 was also mentioned you migh like to note, that the engines from build date CW20/2007 received a altered cylinder head with different piston rings.