20-32 Cummins 5/16/14 4:17 PM Page 24
Cummins Feature
The “Gorilla Girdle” is a proprietary machined piece used to prevent main bearing cap walk by linking all of the main bearing caps together and to strengthen the block by being bolted to the oil pan rails.
one of the founding forefathers of diesel power. Cummins gained a lot of notoriety in 1989 with the introduction into the Dodge truck with a 5.9L, inline six cylinder, and turbocharged diesel engine. From there,
the 5.9L and the later 6.7L, have proven reliable and dependable, giving them more favor to consumers. The love of the Cummins engines by consumers has opened up the opportunity for niche markets in the
Circle 24 for more information 24 May 2014 | EngineBuilder
growing demand for more Cummins performance. One common place that Cummins performance can be found would be sled pull competitions. Sled pull competitions are divided into classes that are limited to the turbo inlet size. For instance, if you were pulling in a 3.0 class, then the turbo inlet size of your combination would be limited to 3.00”. It is often wondered as to what modifications are done in order to reach the amount of power output along with engine RPM that is seen at these competitions. A lot of modifications can be seen on the outside, but there are rare opportunities given to see the actual working internals of the power plant. There are several Cummins builds that can be found in the media, but the question is often asked as to what works and what is truly needed. Of course, that depends on the application, but we wanted to see what Cummins build is on the track and what combination seems to be working for them. We were invited in by Industrial Injection, a diesel parts supplier based in Salt lake City, UT, to get a sneak peak at some modifications that are used for their sled pulling applications. The engine build starts with a stock 6.7L block. The factory blocks are very strong and if the combination is right, structural integrity is not the problem. The blocks are usually bored no more than .020” (yielding a 4.230 bore) and then deck plate honed. Deck plate honing is very important to any engine build for proper cylinder surface. Even though the Cummins block is very rigid, the cylinders can distort as much as .003” when the cylinder head is torqued down. If the block is not properly honed, .003” cylinder distortion can lead to serious piston scuffing especially with the amount of cylinder heat along with major blow-by.