It’s all about sucking and banging this issue.
No, not what you and Polly Pretty Pants get up to in your spare time, rather, what an engine needs most for big power!
Last month we talked about the importance of getting air out of our engines via exhausts, so this month it’s only prudent we discuss sucking that air in for a bigger bang.
Generally, the more you can get in, the better, but the density of air, altitude, humidity and ambient temperatures play a massive part, which is why modern fuel-injected bikes share all these extra sensors and sensory technology to make allowances for variables.
A lot of bikes nowadays use self-mapping tech, using closed loop systems and lambda sensors to pick up exhaust gases before sending the info back to the ECU. The ECU then reads these signals and changes the fuelling accordingly. The same applies for MAP sensors (Manifold Absolute Pressure), which measures the amount of air being sucked via the inlet tract, giving a second indication to TPS (Throttle Position Sensor).
There are exceptions to getting as much air in as possible. It depends on the condition of the air; that air might be slow moving, and that’s the secret with gas flowing heads – getting air into a form that is much more efficient than a standard engine, so modifying an inlet port or exhaust port to increase the volume/speed of the air passing through, be it burnt or un-burnt gases.
You may think that removing metal from that port will increase airflow but in all honesty, it may reduce it. Engine tuning really is a fine art. You can’t just pick up a textbook, get the Dremel out and learn how to tune a motor.
As temperatures rise, air rises with heat and the oxygen content reduces, and you need plenty of oxygen for the bang, but you need to monitor that oxygen content (with an air temperature sensor). We are just above sea level here. If you’re below sea level, you’re probably Jacques Cousteau. The bike has to perform the same, whether it’s here or in the Alps where air is getting thinner and oxygen is reduced, and the bike will constantly adapt along the way without sacrificing performance.
Very hot, humid countries have wet air – light air carrying less oxygen. Here it’s wet but bloody cold, so the air is heavy, highly oxygenated and doesn’t want to flow very fast. So a fish out of water would last longer here than it would in, say, Malaysia. Aerodynamics also play a part in varying air types – if the air is thick, then you’ll need more force to break that air. Anyway, I digress.
Getting air into the engine is obviously a vital task. The easiest, most direct way is through the headstock, although it’s not necessarily the best way. Honda and Suzuki still use twin air tubes on either side, suiting