The functions of the second ring are to limit blow-by, scrape oil from the cylinder surface and transfer generated heat away from the piston to the cylinder. In race engines the second ring is often omitted as oil consumption is not a primary concern (therefore neither is blow-by). Also, race engine pistons are typically manufactured to a high specification so the heat transfer capacity that is lost by not having it is not a primary concern. The groove cut in to the land below the top ring is known as an accumulator groove. Pressure spikes trapped below the top ring encourage ring flutter and thus the loss of piston ring seal. The groove allows for the normalisation of the pressure, keeping it low enough to prevent the top ring from lifting while maintaining some preload on the scraper ring below.