A very popular food product on the market is Activia Fat Free Yogurt. Lauded for it’s nutritional benefits, many health conscious patrons choose it because it is “Fat Free.”
In actuality, Activia Fat Free yogurt contains 0.4g of fat per 100g serving. You astutely point out that this is a contradiction, but according to legal guidelines, any product with less than 0.5g of fat per serving can be entitled, “Fat Free.”
Certain products or machines have intrinsic details or properties that cannot be removed. These details can be minimized or optimized, but never completely removed by definition. Dairy products will always contain a measure of fat content. Turbos will always contain a measure of lag. We know all about yogurt now, but how little Turbo Lag constitutes ‘No Lag?’
In it’s simplistic form, a turbo uses discharged exhaust gases to pressurize intake gases, thus producing more power. There is tremendous energy in the flow of expelled exhaust gas leaving the engine. This is where the turbo kicks in – pun intended.
For the sake of brevity, this article will not delve deeply into the technical makeup of a turbo, but we will consider the basics as they relate to turbo lag.
During the ‘Exaust Phase’ of a four cycle engine, the exhaust valves open and the piston forces the combusted fuel/air mixture out of the cylinder with a plunging movement. Since at the same time as this cylinder is being plunged of exhaust gases, another cylinder on the crankshaft is in it’s power stroke, this exhaust gas is expelled with the full force of the engine’s power. The inertial energy of the flywheel also plays into this. The force of expelled exhaust gases is what “spools” or spins the turbo.
A turbo essentially has two halves, an exhaust turbine and a compressor turbine. The exhaust gas always acts upon the turbo first. The exhaust turbine translates the motion and pressure of the fluid hot gases into rotational inertia. The subsequently spinning half-shaft is connected to the drive shaft of the intake compressor, and this in turn compresses the intake gases from below atmospheric pressure to well above.
Continued at BMWBLOG.com
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