Quote:
Originally Posted by rh0
Also of interest are these structures inside the 4-2 merges of the OEM header for the 20v Toyota 4age. I've only found a few pictures of them and read even less explanation/speculation about their function.
|
Fascinating indeed! There's an old physics experiment involving an incense stick, a vacuum cleaner that can be set to 'blow', and a sheet of perf-board, illustrating Bernoulli's principle - the air flowing on one side creates a low pressure zone and sucks the smoke through from the other side. I'd hazard a guess that's what they're going for here, it may well provide effective scavenging at lower RPMs than a conventional merge.
It may also provide a very small muffling & detuning effect as the initial pressure increase of the exhaust pulse would partially escape sideways through the holes, before the airflow got up to speed and started sucking.
As for the slot, at first I wondered whether it might be to stop some sort of resonance, like the plate itself vibrating at very high frequency
then I realised that without any external surfaces, it would get a
lot hotter than the walls of the tube - I'd say it's an expansion joint to stop (a) the plate buckling and then pulling away from the walls as it contracts or (b) the plate pushing the tube apart.