Plastic automotive engine
The Plastic automotive engine has its origins in the late 1970s with research and work done by Matthew (Matti) Holtzberg of Polimotor Research and his associates. Since then Holtzberg and others have done steady work in the field.
Holtzberg's early work
Matti Holtzberg first attempted to make polymer pistons for an Austin Mini engine in 1969. The pistons ran for only 20 minutes until failure. Holtzberg remedied this by fitting the pistons with aluminium crowns and he sold these pistons to racing builders during the early 1970s.
Matti Holtzberg founded Polimotor Research Inc. in 1979. It was based in Fair Lawn, New Jersey. The company, in cooperation with its suppliers and sponsors, created and raced engines consisting of a large percentage of polymers in the 1980s.
Version one was based on Ford's 2.3-liter Pinto engine and weighed 152 pounds (69 kg) (vs. 415 pounds (188 kg) for its cast iron counterpart). It was designed to produce 318 horsepower (237 kW) at 9200 rpm. It was composed of metal cylinder sleeves, metal combustion chamber tops, metal piston crowns, bearings, valves and seats, and a stock 2.3L Pinto crankshaft. Nearly everything else in the engine, including the block, rods and piston skirts, were made of glass reinforced Polyamide-imide thermoplastic resins manufactured at the time by Amoco Chemicals Co. The engine was never installed in a vehicle.
Another engine, supposedly based upon the Cosworth BDA and YB series engines, weighed 168 pounds (76 kg), half the weight of its metal counterpart. Plastic parts included the engine block, cam cover, air intake trumpets, intake valve stems, piston skirts and wrist pins, connecting rods, oil scraper piston rings, tappets, valve spring retainers and timing gears.
The engine was raced over two seasons. It was raced in a Lola T616 HU04 and competed in the International Motor Sports Association's (IMSA) Camel GT Championship in the Camel Lights (Group C2) category in 1984 and 1985. The car earned several top 5 finishes including its best finish of third in class at the 1985 Lime Rock 2 hours.
Throughout the 1980s, Holtzberg was granted 10 patents for composite engine parts and their methods of production. The patents were issued between 1983 and 1988 and are elaborated on in this section.
The first patent issued was for ignition cables, citing prior art for other non-metallic conductive materials and their ability to reduce RF interference related problems. These cables consisted of a graphite/resin composite conductor strands and a protective silicone sheaf. The strands were to be twisted together and drawn through the liquid matrix material, finally being surrounded by the sheaf. The two parts would be extruded together to form the cable and ensure a well bound structure of thousands of individual graphite composite filaments.
The majority of patents are for Polyamide-imide engine components, with the potential for graphite, glass or titanium reinforcement as a composite. The inventions are claimed to have a superior stiffness-to-weight ratio, be up to 70% lighter than traditional parts and reduce vibration and forces within the engine. The composite parts are also claimed to reduce production requirements due to being injection moulded with consequently reduced finishing work.
Although the temperature, time and other process variables differ between parts, the general manufacturing process follows. The component is first injection moulded and allowed to cool past its plastic deformation temperature. It is then post cured by solid state polymerisation at a series of temperature steps. This is performed in an inert atmosphere which helps to expel by-products of reactions until the polymer is chemically stable. During this process the heat deflection temperature of the material also increases. The part is now cooled and post-processed. Post processing can take the form of machining, insertion or adhesion of metal parts or a simple cleaning of the part.
Composite Castings LLC
In 1990 Matti Holtzberg founded Composite Castings LLC, based in West Palm Beach, Florida. By 2011 they had developed a V4 carbon reinforced epoxy composite engine block with materials supplied by Toho Tenax. The block is claimed by Holtzberg to be up to 50% lighter than an equivalent aluminium model. The blocks are produced to net shape so minimal finishing work is required to make them ready for use. Holtzberg claims that this reduces tooling and production costs by 50% in comparison to die casting.
Fraunhofer and Sumitomo research
In April 2015 the Fraunhofer group in collaboration with the high performance polymer division of Sumitomo Bakelite Co announced their development of a single cylinder research engine with a casing made of injection moulded glass fibre reinforced phenolic resin (55/45 respective composition). The engine weighs about 20% less than an equivalent of aluminium. Their design uses metal inserts in places of high thermal and mechanical stress, for example in the cylinder liner.
Solvay revival of Polimotor
In May 2015 it was reported that the Belgian chemical company Solvay had shown interest in reviving the concept with assistance from Matti Holtzberg. The engine is planned to weigh less than 148 pounds (67 kg) and generate over 420 horsepower (310 kW), it is also planned to be turbocharged. Up to ten components will be replaced with polymer counterparts, these include water pump, throttle body and cam sprockets. The engine was planned to be installed in a Norma M-20 chassis and raced at Lime Rock in 2016 and a possible Le Mans entry in 2017.
Solvay have published press releases regarding several of the components expected to be part of their engine. These are:
- Cam Sprockets made of PAI 
- Intake runners made of PEEK 
- Oil scavenge lines made of PEEK 
- Seals and water components made of PPA 
- Fuel injection rail made of PPS 
- Intake plenum additively manufactured from PA6 
- Oil pump housing made of PAEK 
- Water pump internals made of PPS 
- "One Step Closer to the No-Iron Car". Retrieved 2016-06-10.
- "Is This the Engine of the Future? In-Depth with Matti Holtzberg and His Composite Engine Block". Retrieved 2016-07-18.
- Keebler, Jack (September 1982). "Ford's impossible plastic engine". Popular Science.
- "Plastic Race Engine Returns as Polimotor 2 Project Underway". Retrieved 2016-06-10.
- "Ford in Venture For Plastic Motor". Retrieved 2016-06-10.
- "Bob Roemer tells the story of the IMSA T616-Polimotor, the racing car with the plastic engine!". Retrieved 2016-06-10.
- "1985 Lime Rock 2 Hours". Retrieved 2016-06-10.
- US 4369423, Matthew W. Holtzberg, "Composite automobile ignition cable", published Jan 18, 1983
- US 4432925, Matthew W. Holtzberg & Lawrence D. Spaulding, "Composite piston ring and process", published Feb 21, 1984, assigned to The Standard Oil Company
- US 4433964, Matthew W. Holtzberg; Lawrence D. Spaulding & Steven J. Henke, "Composite timing gears and process", published Feb 28, 1984, assigned to The Standard Oil Company
- US 4430969, Matthew W. Holtzberg & Lawrence D. Spaulding, "Composite rocker arm and process", published Feb 14, 1984, assigned to The Standard Oil Company
- US 4430906, Matthew W. Holtzberg & Lawrence D. Spaulding, "Composite wrist pin and process", published Feb 14, 1984, assigned to The Standard Oil Company
- US 4453505, Matthew W. Holtzberg & Lawrence D. Spaulding, "Composite push rod and process", published Jun 12, 1984, assigned to The Standard Oil Company
- US 4432311, Matthew W. Holtzberg; Lawrence D. Spaulding & Steven J. Henke et al., "Composite valve spring retainer and process", published Feb 21, 1984, assigned to The Standard Oil Company
- US 4433652, Matthew W. Holtzberg & Lawrence D. Spaulding, "Composite valve and process", published Feb 28, 1984, assigned to The Standard Oil Company
- US 4458555, Matthew W. Holtzberg & Billy W. Cole, "Composite connecting rod and process", published Jul 10, 1984, assigned to The Standard Oil Company
- US 4726334, Matthew W. Holtzberg; Lawrence D. Spaulding & Steven J. Henke, "Composite cylinder housing and process", published Feb 23, 1988, assigned to Amoco Corporation
- US 4440069, Matthew W. Holtzberg; Lawrence D. Spaulding & Steven J. Henke et al., "Composite piston and process", published Apr 3, 1984, assigned to The Standard Oil Company
- "Carbon fiber engine block revealed : CompositesWorld". www.compositesworld.com. Retrieved 2016-07-21.
- "Fraunhofer - Research news 04/2015" (PDF). fraunhofer.de. Fraunhofer. Retrieved 2016-07-21.
- "Solvay materials fuel breakthrough innovation of "Polimotor 2" all-plastic car engine". Retrieved 2016-06-10.
- "Resurrecting the plastic engine". Retrieved 2016-06-10.
- "Torlon® PAI Chosen for Breakthrough Cam Sprocket in Polimotor 2 Automotive Project". Retrieved 2016-06-10.
- "Polimotor 2 Chooses Solvay's High-Performance KetaSpire® PEEK for 3D-Printed Fuel Intake Runner". Retrieved 2016-06-10.
- "Solvay's High-Performing KetaSpire® PEEK Polymer Chosen for Oil Scavenger Line in Polimotor 2 Automotive Project". Retrieved 2016-06-10.
- "Polimotor 2 All-Polymer Race Engine Project Chooses Solvay's Amodel® PPA and Tecnoflon® FKM for Water Cooling Components and Seals". Retrieved 2016-06-10.
- "Polimotor 2 All-Polymer Race Engine Project Chooses Solvay's Ryton® PPS and Tecnoflon® FKM for Demanding Fuel Injection System". Retrieved 2016-06-10.
- "Sinterline® Technyl® Powders Boost Polimotor 2 with 3D Printing Technology". Retrieved 2016-06-10.
- "Solvay's Sinterline® technology combined with MMI Technyl® Design shape the future of 3D printed functional automotive parts". Retrieved 2016-11-29.
- "Solvay Announces Polimotor 2 All-Plastic Engine Project Will Mold its Oil Pump Housing from AvaSpire® PAEK Ultra Polymer". Retrieved 2016-07-06.
- "Solvay's Ryton® PPS helps cool Polimotor 2 engine by enabling highly reliable internal components for Pierburg water pump". Retrieved 2016-10-21.