Written By, Mike McGlothlin
CAT 3408
History
Call it excess, call it overkill, or call it king of the hill, the CAT 3408 engine is one of the more unique diesels ever offered in the heavy-duty segment. Released in 1975, this 1,099 cubic inch (18.0L), industrial strength V-8 boasted wet linters, the same 5.40-inch stroke as the 3406 offered during the same timeframe, and a 6.00-inch stroke. It also featured a highly exotic crankshaft, with offset rod journals to improve balance, as the 3408 was a 65-degree V-8 and not a 90-degree power plant. The 3408 was topped off with 4-valve cylinder heads, anchored to the block via six head bolts per cylinder, benefitted from mechanical injection, and most were of the direct injection, turbocharged configurations—hallmarks of early CAT 3408 specs.
Common Applications
Although the 3408 was the largest on-highway diesel engine CAT ever made, its take-rate in Class 8 applications was low in comparison with the 3406. This was primarily due to an inability to quench the big V-8’s thirst for fuel and its overall heft (3,300 to 3,705 pounds depending on configuration), which meant less freight could be carried. Outside of Class 8 trucks (Kenworths and Western Stars especially), the CAT 3408 was (and still is) used in construction, industrial, and marine applications. Spread out all across the globe, you can find them in everything from scrapers, dozers, excavators and gen-sets to commercial fishing boats, trawlers, tug and work boats, utility vessels, and even luxury yachts —applications that helped define CAT 3408 History beyond the highway.
Production Run
The CAT 3408 was produced from 1975 to 1985. Its power ratings ranged from 425 hp to 550 hp on the highway, but marine versions could be turned up to as much as 800 hp. Its discontinuation has been blamed on that fact that the 3406 made similar power yet was more fuel efficient, that the 3408 was highly expensive to manufacture—and that there was no real need for the 3408 and 3406 to compete in the same markets. Despite the 3408’s relatively short production run, it’s still in demand today, 40 years later. Because of this, Caterpillar still manufacturers parts and offers support for the big yellow V-8.
How It’s Remembered
Very much a different animal than the medium-duty 3208, CAT’s 3408 was a true heavy-duty V-8, complete with a gear driven water pump like the 3406, wet liners like the 3406, the whole nine yards. As such, it’s extremely durable, and known as a million-mile/20,000-hour engine. In gen-set form and in countries with lenient emission regulations, the 3408 remains in regular use and enjoys solid demand. And while fuel consumption is high, there is never any shortage of power with the 3408. Of course, they carry a lot of “cool factor” with them, especially when packaged into a Class 8 truck. There, the CAT 3408 is the ultimate conversation piece.
Sources:
Big Bear Engine Company
https://www.4btengines.com/cat-3408-engine/
Still In High Demand
https://www.depco.com/blog/cat-3408-engine-is-still-in-demand/
Great Engine Info
