Engine louder

[Litchkar]

strange question, I swapped out my cast iron heads for aluminum ones. Nothing else was changed, but the engine is louder. Not the valve train, or exhaust. I know it picked up power with the better flow, but do cast heads muffle sound more than aluminum ones?

 

[moparleo]

Cast iron is a lot denser material, lead is a very dense material. Sound does not travel as well through denser materials. Since aluminum is less dense, sound amplifies and travels better through it. If you put headers on it, it would be even louder because although headers are generally made of some type of steel, the wall thickness is very thin. This allows more sound to penetrate through the tubes.

 

[Litchkar]

Cast iron is a lot denser material, lead is a very dense material. Sound does not travel as well through denser materials. Since aluminum is less dense, sound amplifies and travels better through it. If you put headers on it, it would be even louder because although headers are generally made of some type of steel, the wall thickness is very thin. This allows more sound to penetrate through the tubes.

Thanks for the info, 1st time with Al heads, I guess it is the sound of performance.

 

[Racer57]

Your hearing the sound that aluminum threads make when starting to strip out !! Sorry, just joking.

 

[AUSTA]

Cast iron is a lot denser material, lead is a very dense material. Sound does not travel as well through denser materials. Since aluminum is less dense, sound amplifies and travels better through it. If you put headers on it, it would be even louder because although headers are generally made of some type of steel, the wall thickness is very thin. This allows more sound to penetrate through the tubes.

Yesterday i started my new 340 stroker (393 3.79 Molnar) i used the same roller lifters off my old engine when i started it there was a lot of valve train lifter noise . i took off the rocker cover & checked the rockers all were set right I have changed from a mopar 4 barrel cast intake to an Aluminium dual quad Fast fuel EFI after reading this it is probably the same scenario