US engineer Matti Holtzberg has teamed up with Belgian chemical company Solvay to work on the Polimotor 2 project.
This is a four-cylinder, double-overhead CAM engine that will be installed in a Norma M-20 concept car to compete at Lime Rock Park, Connecticut.
Using plastic usually raises concerns over how it will deal with the heat in an internal combustion engine.
“Everybody always asks that question,” Holtzberg told The Engineer. “The exhaust port and the combustion chamber is an aluminium casting that’s moulded into the cylinder head and then the pistons run in either a cast iron or a nikasil-coated bore.
“There is metal where the heat is and that is about the only two places. Everything else is a composite material.”
Holtzberg, the president of Florida-based Composite Castings, had success with his first Polimotor engines in the 1980s, when they were used in an Amoco Chemical Company-sponsored racing car.
Amoco eventually stopped competing, but Holtzberg continued improving the engines. The importance of lightweighting and fuel efficiency then led to a renewed interest in the technology.
“That is why I’m bringing all of this back, to show the automotive industry what you can do. They will see it racing so they can’t say it doesn’t work.”
Solvay will provide up to 10 thermoplastic components to demonstrate lightweighting through metal replacement.
These will include the water pump, oil pump, water inlet/outlet, throttle body, fuel rail and cam sprockets.
The aim is to develop an engine weighing 63–67kg, about 41kg less than today’s standard production engine.
Coventry University director of low carbon vehicle programmes Bernard Porter said there is an overall trend to reduce the weight of power units.
“Whether plastics could really accelerate that trend or would even be particularly relevant I think is a bit more open to debate,” he said.
“I think it would be foolish for anyone to say it looks unfeasible, but on the other hand there are a lot of technical problems to overcome. I can only imagine that the companies involved are fairly confident they know how to do that,” he added.
Imperial College London professor in turbomachinery Ricardo Martinez-Botas said to be successful the technology would need to show it could deal with the issue of cooling, the peak pressure related to modern turbo boost systems, and gaining customer confidence over maintenance, repairing and obtaining and replacing parts in a car with a plastic engine.
“This engine will need to be cooled because the temperatures of combustion are huge, so the question is whether you alleviate some of the cooling that would normally be necessary for a metal engine, and if you do then there is a benefit with a plastic engine,” he said.
Holtzberg said his racing car engine would reach 450bhp at 8,000rpm. “It is turbocharged. It will have two atmospheres of boost. There are some design things that I do to take stress out of the block that I can’t go into but I will tell you that the material is twice as strong as the grade of cast aluminium used,” he said.
“If you don’t do it then nobody will ever do it. I look back 20 years and if you had told me BMW was going to have a carbon fibre car I would say you were crazy.”