In four - stroke engines the exhaust ports are generally opened just prior to bottom dead centre piston position, thus giving a maximum expansion ratio. (mechanics.stackexchange.com)
Meanwhile sitting dead centre of the bottom bezel is the only button this machine uses in navigating the interface — it maximises and minimises apps — though it's not actually needed as a gesture also takes care of the same duty. (trustedreviews.com)
The engine features a crankshaft - mounted rocker assembly that can be tilted to vary the Top Dead Centre position of each piston and therefore change the combustion - chamber volume. (motoring.com.au)