PIPE 7W5672 - Caterpillar

Naturally-Aspirated 3304 And 3306 Engines With Precombustion ChambersDescription of Change: High compression pistons can be used in the above engines that are used at high altitudes (more than 1520 m - 5000 ft). These high compression pistons will change the compression ratio to 21:1. This increase in the compression ratio will permit more complete combustion, which will give an increase in performance and decrease exhaust temperatures. When engines with the original lower compression pistons are used in high altitude applications, the service life of the pistons is decreased. The thinner air at high altitudes will cause a "too-rich" condition. This results in an increase in black exhaust smoke, an increase in exhaust temperature, a reduction in power and possible piston failures.
Adaptable To: The 8N3184 Piston Body Assembly and the 9S3068 Piston Ring Group can be used in all 3304 and 3306 NAPC Engines in high altitude applications. Make a reference to the Rack Setting Information charts for the correct fuel settings for the engine. The high compression pistons are used in 3304 Industrial Engine Arrangement 1W2468 and 3306 Industrial Engine Arrangement 1W2469. They are also available for 920 Loaders with Custom Shop Engine Arrangement 2Z639 and on 930 Loaders with Custom Shop Engine Arrangement 2Z606.
The 8N3184 Piston Body Assembly can also be used on some 3304 and 3306 PC Engines that have turbochargers. For these engines, dealers can contact the Engine Product Analyst in their appropriate Service Engineering group. Factors such as the amount of load and the horsepower will have to be considered before a recommendation can be made on which piston design to use.
High compression pistons are not needed on direct injection engines used in high altitudes.