Category: Diesel Engine


Role of Piston Skirts In Diesel Engine

Piston skirts is an important part of piston which covers the lowest. Piston skirt is responsible to keep piston from shaking unreasonably within the cylinder during working. Providing proper lubrication is the main task of Piston Skirts by holding and transporting oil to wall of the cylinder. To prevent scuffs on cylinder wall chemical layer coating is made on Piston Skirts which helps in proper lubrication.

Especially Heavy Diesel Engines requires proper lubrication in the cylinder walls and it requires special Piston Skirts which can perform lubrication process in heavy diesel engine.

Therefore, PIA has introduced High Performance diesel engine overhaul Piston Skits.

PIA’s Piston Skirts

PAI’s Piston Skirts are treated with a new and highly developed anti-friction coating process. The coating is designed to lower scuffing and wear while providing a dry lubrication that is highly resistant to contamination, and reduces parasitic drag.  HP-3 is a proprietary formulation of anti- friction coating applied to the piston skirt, to decrease friction on the cylinder walls.


As the largest friction area, the Cylinder Wall represents the largest loss of power and efficiency anywhere in the engine. HP-3 coating drastically reduces friction and allow for tighter clearances between the piston and the Cylinder Wall. This reduction in friction and clearance improves overall performance, lowers oil usage and oil temperature; ultimately increasing the life of the Skirt.

“HP-3 Coating drastically reduces friction and allow for tighter clearances between the piston and the Cylinder Wall.”

Check Out: PIA’s High Performance Diesel Engine Rebuild Kits of Cummins, International, CAT, Mack and Detroit Offered By H.D. Kits.

Hp-3 Dry Film Lubricant

Coating Process

HP-3 Dry Film Lubricant coating is applied as a spray process. Different surface preparatory methods appropriate for the substrates are used prior to the coating process. Coating thickness is varied to suit the application. Typical coating thickness for piston skirts is 1 to 1.5 mil (12 to 37 microns).



Low coefficient of friction, provides intermittent dry lubrication, Increased load carrying capacity, wear resistance, corrosion protection.


Lean, Mean, And Clean

Diesel has always been the bad boy among all fossil fuels. There is good diesel and bad diesel depending on the exact process of converting the crude to the diesel you get at the stations. Diesel is still cheaper than gasoline or petrol and it is still the go to fuel for commercial vehicles. With tightening environmental norms and emission regulations, diesel engines are facing a tough task. Add to that the reducing mileage because of focus on emissions or the clogged diesel particular filters and the owners of commercial vehicles, truckers and transport companies are having a tough time.

While diesel engines have been getting a bad name, there is the Caterpillar C15 diesel engine that is lean, mean and clean. The Caterpillar C15 is expected to clock 1,000,000 miles. The engine can power semis where the total gross weight of the vehicle will be up to 80,000 pounds. The engine is clearly robust and omnipotent. It can run rigs that require steady power and an excessive torque. The C15 diesel engine is powered by ACERT or Advanced Combustion Emissions Reduction Technology to adhere to the stringent emission regulations.

Designed to be sturdy

The Caterpillar C15 diesel engine is designed to be sturdy, to offer enough boost to endure compression and facilitate precise injection events so fuel is used as efficiently as realistically possible. The engine is more efficient than its counterparts and that again helps in fuel economy, especially during regeneration.  

The Caterpillar C15 diesel engine has a compression ratio of 18.1, it has mechanically actuated electronically controlled unit injection system or MEUI, there are two turbo charges and the engine is controlled by Caterpillar’s ADEM A4 ECM. The sturdy street pistons, four-bolt connecting rods, 300,000 mile particulate filter, 20,000 miles of oil change interval and expected engine life of at least 1,000,000 miles ensure you have a durable engine. The Caterpillar C15 diesel engine has displacement of 15.2L, the available power levels are 435-625 hp at 2,100 rmp, the engine weighs 2,890 pounds and has an oil capacity of 41 quarts.



Federal Mogul Holdings Corporation, better known as FDML, has come up with two piston skirt coatings: EcoTough –New Generation meant for gasoline run engines and EcoTough-D meant for diesel run engines. With the company innovating constantly, these new offerings come with improved formulation to reduce the friction and wear and tear in engines, helping it to tackle the varying temperatures and extreme conditions it has to operate in, especially for the downsized and turbo-charged engines.

Gian Maria Olivetti, the Chief Technology Officer of Federal Mogul Powertrain said that their main motive is to reduce the frictional losses by leveraging on their expertise on material. With their new range of EcoTough coatings, the durability of pistons are set to improve, thereby increasing the life of piston even in conditions where there is a high thermal and mechanical load in the present day engines that are efficient.

The solutions for gasoline and diesel engines differ greatly, mainly due to the relative difference in their combustion loads, geometry of piston and the lubricity of the fuels. They have worked on these differences and come up with specific coatings for each type of engine. The new generation of EcoTough coatings comprise of metal oxide-reinforced resin along with solid lubricant particles that are embedded. This coating is applied for a thickness of 15 microns and the wear and tear comes down by a whopping 40% over other coatings, improving the reliability of the piston even in extreme conditions. It also reduces the friction in piston by over 15% when compared to the standard coatings available in the market, which results in an improved efficiency of the engine.

The EcoTough range of coatings, which were developed after extensive rig testing, are now undergoing validation checks by automobile manufacturers before they will be used commercially.  EcoTough coatings are compatible both with aluminum and steel diesel pistons for commercial and passenger vehicles. Federal Mogul leveraged on the fact that diesel has better lubricity and the structural stiffness of diesel pistons are more, which enabled them to formulate the coatings accordingly. They also reinforced a polymer based coating with short length carbon fibers which comprised of embedded graphite that constituted to be a solid lubricant in EcoTough-D. This brought the friction in piston down by 35% when compared to conventional coatings. The water resistance of the coating saw a 30% improvement.

Almost 17% of the frictional losses in the engine arise only due to the piston skirt and piston pin, as per Dr. Frank T.H. Dornenburg, who leads the Technology department for Pistons at FDML. In a bid to reduce the friction and wear of piston skirt and cylinder surfaces, skirt coatings have proved to be effective and have also helped in achieving the interrelated targets. The application of coatings can be done using an automated and large scale production process, which will result in lower costs.

An Overview of Federal Mogul

Federal Mogul is an established company worldwide and supplies products and services to different automobile manufacturers and servicers from all over the world of all light, medium, heavy-duty and commercial, marine, rails, aerospace, power generation and industrial sector of markets. With the constant innovation at Federal Mogul, automobiles have been able to achieve better fuel economy, lower emission levels and better safety levels.

There are two independent lines of businesses at FDML run by two different CEOs, who directly report to the Board of Directors.

FDML manufactures components suited for automotive, heavy-duty, and industrial and transport applications. There are over 20 recognized brands in the global automobile aftermarket that are sold by Federal Mogul which include braking, wipers and different chassis components.

It was started in 1899 in Detroit and is headquartered in Southfield, Michigan. There are over 53,000 employees worldwide on its payroll.


Much before refined diesel was stringently controlled by EPA norms and international agencies, there was raw or crude diesel. Much before sleek diesel engines, there were large, rather odd looking engines that were primarily tasked for function and not for comforting or fluidic designs of the vessels. One of the finest masterpieces of such diesel engines can be explored in the WWII Balao Class Submarine.

When the Second World War was inching towards an end, the navies of the Allied Forces needed more dominating and powerful presence in the waters and under. Thus, one needed submarines that could be in the waters for a long time and often in troubled enemy waters. For such operations, one needs an engine, rather a power plant that is reliable and has enough jus to last the mission.

The USS Pampanito (SS-383) was the first of its kind boat built which could store 110,000 gallons of diesel. There were several such submarines built from 1942 through 1944 which formed the Word War II Balao Class Fleet.

The USS Pampanito had 4 Fairbanks Morse 38D 8 1/8 model motors, which used opposed piston, in-line 10-cylinder engine with a bore of 8 1/8 inches and a stroke of 10 inches. Each ship had an auxiliary engine, the Fairbanks Morse Model 38E 5¼, which was a 7-cylinder, opposed piston, air-starting engine rated at 440HP with a bore of 5 1/4 inches and a stroke of 7 1/4 inches.

While operating at the surface, the submarine had two diesel engines driving the motor generators and two more powering the batteries. There was a fifth engine to provide electrical power for the auxiliary equipment onboard and the lights. The engines could operate at 300 rpm with peak performance clocking at 400 rpm.

The most stunning feature of the USS Pampanito was the ability to store 110,000 gallons of diesel for the five engines. To make this possible and to make the technology work, the ship had a bunker with a centrifugal purifying system. The Fairbanks Morse 38D 8 1/8 engines could generate 1600 horsepower.

Fascinatingly, despite the technology being almost seventy years old, Fairbanks Morse still manufactures spare parts for the engine as the engine had been in widespread use for many years after the war, well into the eighties.

Presently, the USS Pampanito is at pier 41 at the San Francisco Maritime Museum.