pressure in the ADI system moves the derichment diaphragm in the fuel control to close off the derichment jet, reducing the fuel flow to a leaner mixture which produces higher engine power by raising the mean effective pressure. This causes the cylinder head temperature to increase to a very high level, which dramatically increases the risk of detonation (see: engine knocking). Adding the ADI fluid raises the mean octane level of the charge preventing pre-ignition and also lowers the cylinder temperatures to a more acceptable level. As this operation takes the engine well beyond its normal design limits, this power setting is not suitable for prolonged use. Once the ADI fluid is exhausted or if the mixture control valve is moved out of the military position, the fuel control derichment diaphragm pressure is lost, and the derichment jet is opened once again for normal fuel flow. Variants Bendix-Stromberg produced a number of pressure carburetor styles and sizes, each of which could be calibrated to a specific engine and airframe. There are four styles: PS single barrel carburetor PD double barrel carburetor PT triple barrel carburetor PR rectangular bore carburetor Each of these styles is available in a number of sizes, using measurements of the area of the bore on a rectangular bore, or a special system for circular bores, and the actual square inches of the throat area for the rectangular style. PS style Single round throat, can be mounted updraft, downdraft and horizontal with slight changes PS-5, PS-7, PS-9 PD style Double round throat, can be mounted updraft and downdraft with slight changes PD-7, PD-9, PD-12, PD-14, PD-16, PD-17, PD-18 PT style Triple round throat, can be mounted updraft and downdraft with slight changes PT-13 PR style Two or four rectangular throats, can be mounted updraft and downdraft with slight changes PR-38, PR-48, PR-52, PR-53, PR-58, PR-62, PR-64, PR-74, PR-78, PR-88, PR-100 Bendix used a special method to identify round carburetor bores. The first inch of bore diameter is used as the base number one, then each quarter of an inch increase in diameter adds one to the base number. Examples: a 1-1/4 inch bore would be coded as a size number 2 (Base number 1 + 1 for the 1/4 inch over 1 inch) a 1-1/2 inch bore would be coded as a size number 3 (Base number 1 + 2 for the two 1/4 inches over 1