‘ The carbon builds up and reduces the area that air has to flow through the inlets to the cylinders and there is a dramatic reduction in power’
The R8’ s V8 differs from the RS4’ s slightly, the changes make no difference to its susceptibility to carbon buildup though
In an ideal world, the air in the intake would always be clean and pure, but oil and deposits creep into the intake.‘ Over time, they gather in areas of lower pressure – particularly on the back of the valves and in the back radius of the head-valve area,’ says Steven.‘ It greatly restricts the intake port flow and reduces the engine’ s knock threshold.’
What are the effects of the issue?
Unfortunately, the buildup of carbon doesn’ t just restrict airflow.‘ The carbon buildup can also clog rings and stand valves off the seat, affecting compression.’ But even worse, the problem itself compounds the issue.‘ As airflow stagnates and more and more drop out builds up, the worse it gets. It’ s exponentially worse after a certain point.’
Air flow is the major issue, though. The carbon builds up and reduces the area that air has to flow through the inlets to the cylinders.‘ Port flow is critical to engine performance. With this [ carbon buildup ], port flow is lost and there is a dramatic reduction in power. We recommend that the job is tackled before it is required – that is, before the owner experiences a reduction in performance.’
‘ The carbon builds up and reduces the area that air has to flow through the inlets to the cylinders and there is a dramatic reduction in power’
How to fix the issue?
If you’ re taking an engine apart completely, which, of course as a reader of the Engine Rebuilder, you may well do, then you can clean the valves and head in whatever way you like without damaging other parts of the engine. But the removal of carbon deposits within the intake can be solved without taking the entire engine apart. There are potions and liquids on the market that can supposedly remove carbon buildup, but there’ s only one way to be sure all of the deposits have been removed: to physically get to the inlet and valves and clean them until the buildup has gone. So, some dismantling is required.
To get to the Audi 4.2’ s intake ports, Regal removes the engine’ s air intake, intake manifold and the‘ air splitting’ dividers from the head. Then any loose deposits are removed before ensuring that the remaining carbon buildup is
54 The Engine Rebuilder Issue 04