Common Rail Engines

Many modern trucks are equipped with a common rail fuel pressure system. This system was originally developed for Fiat vehicles and then expanded to the whole market because of its advantages. The common rail is a relatively simple system. A common rail, or accumulator, acts like a pool containing a fuel volume. Having a volume of fuel pressurized and ready to inject minimizes the negative effects of pressure waves and the instability they cause when calculating the amount of injected fuel. A high- pressure common rail system also has the advantage of being able to inject a lot of fuel quickly and accurate amounts of fuel multiple times within milliseconds. This means you can utilize things like pilot and post-injections.

When tuning a common rail system, the injection pressure can be adjusted. More isn’t necessarily better all the time. It must be finely tuned because, just like anything else, there are trade-offs. So, how does increasing injection pressure affect how the engine runs?

First, smaller fuel droplets and higher injection speeds will improve the mixing process. Faster mixing means shorter ignition delays, which increases power. In some cases, we have seen gains of 200 lb.-ft of torque in the low rpm ranges. Too much of it can act like advanced timing, creating higher cylinder pressure. This can lead to shortened engine life if pushed too far. Inside the cylinder, more trade-offs continue. A temperature increase inside the cylinder leads to higher pressures and more engine-out NOx. This causes the aftertreatment system to spray more DEF. The trade-off is that you have increased cylinder pressure without adding any fuel. This means you make more power on the same amount of fuel, which leads to higher fuel efficiency.  

Generally speaking, increasing common rail fuel pressure in a tune is a good thing. There are things to keep in mind and feedback data is critical to know how far to push things. The increase in NOx is not a good thing, but an increase in fuel pressure also means less unburned fuel, less smoke, and less soot emissions. The drop in unburned fuel is due to the smaller fuel droplets, wider spray, increased fuel velocity, and other factors previously mentioned that improve the mixture. I mean the fuel and air are evenly distributed in the cylinder by improved mixture. This is just one of the many knobs that we can adjust with a tune on a modern engine.

Each moving part in your engine require clean oil for proper lubrication and long life. Engine oil doesn’t just lubricate it also cleans, cools and seals internal components. It cleans by removing and suspending solid and liquid contaminants such as soot particles, wear metals, fuel, coolant, and additive packages added to those liquids. Engine operation degrades oil and must be changed to remove suspended contaminants and restore optimal lubrication properties. Oil degradation depends on several factors such as engine age, engine technology, emission standard, the environment the engine is operated in, how the engine is treated, how much power it produces and much more.

One easy thing you can do to extend your engine’s oil life to add our TBN booster. TBN, or total base number, is a measure how acidic your engine oil is. The base number will steadily decrease as the oil reserve alkalinity depletes by the progressive neutralization of acids from combustion. An increase in acidity can be caused by several things such as excessive fuel dilution, poor combustion from a failed injector, excessive blowby, glycol contamination from coolant, or extending your oil change too far. By periodically adding oil as your engine consumes oil you will increase the total base number. Based on the factors previously mentioned, this may not be enough. If you see a drop in TBN our TBN booster will restore the engine oil back to a proper pH and prevent potential engine component damage.

Because of these factors, you should consider reaching out to our experts at Pittsburgh Power to determine if and how much you can extend your oil drain. Our OPS bypass filter system helps your engine oil stay cleaner and can save you money by extending oil drains. When considering extending your factory oil drain interval you need to use data to make those decisions. You get that data from consistent oil sampling and speaking with experts to analyze your sample. Without oil samples you are just guessing and will shorten your engine’s life.

Lastly, our sale on the OTR diagnostic tool will be ending soon. It is currently on sale for $420 and that is the lowest price it has ever been! The OTR tool can save you a tow bill by being able to check and clear codes, perform a parked regen, and reset aftertreatment values. Trucking is tough right now with low rates, don’t waste money having someone else check codes for you. For more information call us at 724-360-4080 or visit us at PittsburghPower.com.

Written by: Leroy Pershing, Pittsburgh Power Inc., .3600 S. Noah Drive, Saxonburg, PA, 16056 Phone (724) 360-4080 Email: [email protected] Website: www.PittsburghPower.com