MTFCA Forum

Do lighter aluminum pistons significantly reduce vibration?

No, not in my experience.

Is a counter balanced crankshaft the answer?

Weighing and balancing pistons and rods would probably have a greater effect on reducing vibration. This assumes that your other rotating engine components are balanced too. My T runs fine with cast iron pistons. Contrary to current automotive wisdom, my modern has a 2L 4-cylinder engine with an aluminum block and steel pistons. That seems backwards to me, but it runs really smooth.

I guess the only improvement I’ll do going back up is the one piece valves.

ryanpad wrote: ↑

Fri Mar 22, 2024 6:01 pm

I guess the only improvement I’ll do going back up is the one piece valves.

They built over 15 million model T Fords with cast iron pistons and etc.
Most ran until they were worn out 4 times over being stock or repaired with what was around at the time.
Build your engine to the best you can afford to do and have fun with the T.

A simple answer is maybe. It may even be noticeable. The new alloy pistons are very well matched in weight, so that's a good start. They are much lighter than the old cast iron items, so that would help too. But you may still not notice any difference, especially at normal T speeds.

The difference becomes more noticeable when you fit a counterbalanced crankshaft, balance the rods, flywheel assembly, transmission drums etc.

Allan from down under.

Well-designed aluminum pistons that are properly fitted make a substantial improvement in performance. Lighter weight gives lower bearing and connecting rod inertia loading and quicker acceleration. Modern design pistons and rings give far better durability and oil control with less blow-by than original designs. Aluminum pistons allow an engine to run at somewhat higher RPM without loss of durability. Aluminum pistons together with a counter balanced crankshaft, one piece valves, a good cam, and a good auxiliary oiler make for a much smoother and more durable engine than the original equipment while providing more usable horsepower, better fuel and oil economy, and will allow for better hill climbing and higher sustained road speeds.

Improvements aimed at increasing performance are best reserved for later model cars, particularly the 1925 and later cars.
However, significantly reducing engine vibration can benefit earlier cars by reducing wear and stress on the entire car in the case of earlier cars that are driven extensively.
Very early cars are lighter than the later ones and had more power to begin with, besides being a lot rarer.
With a very early car, I would strive for originality over performance.

One thing not mentioned is that Aluminum expands more than iron. For that reason if the engine overheats it can cause the engine to seize. This can score the cylinder walls. Norm

Correct running fit is essential with any type piston, and aluminum pistons likely would need to be fitted with more cold clearance than cast iron ones. As for scoring, a cast iron piston would probably do more damage than an aluminum one would in that situation. Quality modern aluminum pistons have very good expansion control as well as excellent oil control. I'd want to use them in any engine that I expected to put road miles on. Exceptions would be a very early car or an extremely low miles later one with original internal engine parts in good condition.