Noise insulation, Engineer types opinions needed Options

[nivekdodge]

Just a thought

There's another thread today discussing using perlon for the back pad and if it was quieter or not. Something I've notice is Some GM hood have their inner surface looking like a golf ball. There are 3" round divots and when asked about it I was told it reflects the sound back to the motor and that kills the sound.Anyone know if there is truth to this?

This would of course be in the engine compartment.

Kevin

[vitamin914]

This got me curious... Head impact protection on the hood is what it is.

Found a 2008 GM research paper at the NHTSA...

ABSTRACT
Besides functioning as an engine compartment cover, the hood of modern vehicles can also help manage the impact energy of a pedestrian’s head in a vehicle-pedestrian impact. However, a hood’s ability to absorb impact energy may be impeded by the proximity of the hood to components packaged inside the engine compartment, i.e., by its underhood clearance. For example, for a given hood design, the hood’s ability to absorb impact energy through deformation can be significantly reduced when the hood and engine block are in close proximity. Therefore, a large underhood clearance would be preferred for pedestrian protection. However, it could negatively affect driver visibility, as well as a vehicle’s aerodynamics and aesthetic appeal. This paper presents a sandwich hood design that has a potential to improve the hood’s ability to absorb the impact energy of a pedestrian’s head with a relatively small underhood clearance.


Final conclusion was a corrugated under hood works, but is 27% heavier than the standard hood and was not evaluated for manufacturability. Guess they figured it out and put it into production. But like Superhawk said, designed for regulations to the detriment of the vehicle and does nothing for the driver or driving experience.

Found references to a Mercedes patent for putting in pedestrian hood airbags. Today our 914s would weigh 3000+lbs with this thinking. Isn't that what the 718 weighs?