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Intake ports: what are they telling us abt the S4 manifold?
OK - have at last attacked the filler neck oil leak = manifold removal.
Has been 12 years since I last saw these intake ports, however in that time I've done much study of port airflows and shaping so I'm looking at the ports (and manifold) with new eyes, so to speak.
What struck me were the different burnt oil patterns on the walls of every port. Pics below.
Some ports looked to be scrubbed clean c/- airflow, while others had large areas of discoloration, that IMHO represent areas where airflow is reduced or stagnant, allowing oil to settle and char. There are also color variations in the bowls of some ports.
The ends of the manifold runners show matching patterns.
Poking around a bit further I find the inlet ports are angled at approx 55 deg to the block face, while the exit angles from the manifold runners are all over the place like a dog's breakfast (technical term there), but mostly 70-90 degrees, meaning the airflow hits the floor of the port rather than flowing parallel to the floor.
Looking back up the intake runners you'd be hard put to describe some as 'runners' in the true sense of the word, rather they appear as a wavy sort of tube.
My view is these flow patterns indicate areas of turbulence and stagnation, all caused by the intake manifold and therefore why it's a total waste of time and money trying to make serious power with this 'thing' stuck on top of the motor.
(Not Dwayne quality pics. Sorry).
Last edited by UpFixenDerPorsche; 11-23-2014 at 02:09 AM.
The spray of gasoline into the ports is what keeps them clean - perhaps the patterns and orientations of the injectors also play a part in the patterns of deposits in the ports.
The spray of gasoline into the ports is what keeps them clean - perhaps the patterns and orientations of the injectors also play a part in the patterns of deposits in the ports.
Fair point Wally, but as it happens I have the manifolds off both the GT and the S4.
The port 'patterns' are 'very close' in both motors, as are the patterns inside the ends of the manifold runners. Clean ports match with clean runner ends and vice versa. Methinks there's a message in there.
What struck me were the different burnt oil patterns on the walls of every port.
It's fuel, not crankcase oil. The same old-gas goop grows even if crank venting is disconnected from the intake. Reflected injector spray and/or reversion - half the injection pulse is sprayed onto closed valves.
It appeared to me that the goop region was approximately the same length for each cylinder. The shape/length of the tube feeding the cylinder moved the region closer or farther from the valves.
It's fuel, not crankcase oil. The same old-gas goop grows even if crank venting is disconnected from the intake. Reflected injector spray and/or reversion - half the injection pulse is sprayed onto closed valves.
It appeared to me that the goop region was approximately the same length for each cylinder. The shape/length of the tube feeding the cylinder moved the region closer or farther from the valves.
Hey that's a great thread PorKen. Yes, fuel not oil, and linked to batch firing. As you observe some ports are much cleaner than others, the cleaner ones having better flowing runners.
It's fuel, not crankcase oil. The same old-gas goop grows even if crank venting is disconnected from the intake. Reflected injector spray and/or reversion - half the injection pulse is sprayed onto closed valves.
It appeared to me that the goop region was approximately the same length for each cylinder. The shape/length of the tube feeding the cylinder moved the region closer or farther from the valves.
11-21-2014, 07:28 AM
Intake ports: what are they telling us abt the S4 manifold?
