At Wagler Competition Products, the quest for diesel engine performance is a relentless pursuit. Recently, Jeremy Wagler and his team embarked on a testing regime to examine how eliminating the end gap on diesel piston rings can change engine performance, particularly on the 6.7 Cummins engine. This study not only aimed to explore potential power gains but also to assess the effects on engine output.
The 6.7 Cummins Engine And Modifications
The experiments were performed using one of Wagler’s Street Fighter engines, which is built around a 2019 6.7 Cummins base. This particular model has been modified to address common lifter failures and includes enhancements to ensure longevity while testing. The objective was to study the impact of piston rings on turbo efficiency, crankcase pressure, and overall flow dynamics.
Jeremy Wagler (left) and Lake Speed Jr. (right) discuss the engine and the testing parameters about to take place.
Objective of Data Collection
The main goal of the tests was to compare conventional gapped piston rings with Total Seal gapless second rings within the same engine. By adjusting variables such as fuel injection and boost levels, the team could monitor how changes in crankcase pressure affect engine performance. They utilized advanced diagnostic tools, recording crucial data points such as fuel consumption, boost levels, power curves, and blowby rates.
Oil Analysis
An essential component of the study was analyzing oil samples taken from the engine. By comparing used oil with fresh oil, the team could determine the degree of fuel dilution — a primary cause of oil degradation in engines. Regular oil analysis helps in understanding how well different piston rings seal and protect the engine oil from contamination.
Baseline Testing The 6.7 Cummins
To establish a benchmark, the engine was initially run with 15W-40 Rotella T6 oil and 300 cubic inches of fuel. Consistency was key, so the same turbo, injectors, and pumps were used throughout the testing phases. From this baseline, detailed power and torque curves were generated, setting the stage for the next phase of testing.
The 6.7 Cummins Goes Gapless
After the baseline tests, the engine was carefully disassembled, and the conventional piston rings were replaced with gapless second rings. With the new rings installed, the engine underwent the same testing parameters as the baseline assessment. The team pushed the engine from factory default power outputs to maximum output, stressing the engine across various levels.
The Results
One observation was related to crankcase blowby. With the conventional rings, there was noticeable blowby, but with the gapless rings, it was significantly reduced (from about 11 cfm to 5.5 cfm at peak). This change suggested an improved seal provided by the gapless rings. Although the power gain was modest (approximately 8 to 10 horsepower), in competitive scenes, even small increments can be crucial.
Consistency was paramount to ensuring accurate results.
Oil Condition Improvements
Another critical observation was oil cleanliness. The gapless rings appeared to maintain the oil’s integrity far longer than with the conventional rings, which turned the oil black rather quickly after testing began. This outcome indicates better combustion sealing and reduced fuel dilution with the gapless rings.
Post-Testing Analysis
The final phase of analysis will involve laboratory examination of the oil samples to quantify the exact levels of fuel and soot in the oil. This data will help confirm the visual observations and provide a detailed comparison between the baseline and test results under various conditions.
This testing highlights the importance of empirical data in engine tuning and performance optimization. Wagler’s approach is rooted in science, not speculation. This ensures the results are measurable and repeatable, providing valuable insights that can be trusted by engine enthusiasts and professionals alike.
