4 ms·

Presumably there are mechanical (heat, pressure, shock etc.) limits to how you build an engine that limit what you can do to improve safety? As light and small

by zelos 10y ago

Presumably there are mechanical (heat, pressure, shock etc.) limits to how you build an engine that limit what you can do to improve safety? As light and small as modern engines are, they're still a big lump of iron/steel/aluminium.

creshal 10y ago
Sure, but how is an empty space better at absorbing impact energy than that?
- codeduck 10y ago
  Placing an engine in that empty space means that there is less space available for the car's crumple zones to deform before the engine intrudes into the passenger safety cell. A tesla can have its entire front concertina'd down to nothing without anything entering the safety cell. A front-engined normal car cannot do this; typically 50 to 60% of the length of the front of the car is engine. While external parts of the engine may crumple, the cylinder head and main section of the engine by necessity need to be milled from solid metal; These will not crumple, they will be pushed into the safety cell if the collision is energetic enough.
  - jacquesm 10y ago
    In modern cars the design is such that the engine is pushed under the car if there is enough energy in the collision.
  - ssmoot 10y ago
    In addition to the engine going under the vehicle (even at fairly low speed crashes; just watch NHSTA videos on YouTube), the front motor in a Model S is more dense and weighs about the same as a 4 cylinder engine, transmission and accessories. I'm gonna call that a wash until I see evidence to the contrary. Straight on collisions aren't even the toughest ones to pass. It's the small offset tests that really seem to give manufacturers a hard time. And no engine there.
- DanBC 10y ago
  When empty space gets pushed into the cabin it doesn't amputate legs. When an engine gets pushed into the cabin it might amputate legs.
  - kerryfalk 10y ago
    This isn't what happens, though. As others have mentioned, the engine ends up under the car.
- slaxman 10y ago
  You want the front of the car to absrob the energy. When it crumples, it absorbs the energry and lesser energy is transferred to the passengers. The Engine is tough and will not crumple. It will thus not absorb the energy but transfer it to the passengers.
  - creshal 10y ago
    And as I already mentioned before, this is simply not true, you can make engines that crumple extremely well.
    - CompelTechnic 10y ago
      Could you provide some evidence/ examples?
      - creshal 10y ago
        https://youtu.be/mnI-LiKCtuE?t=265 https://youtu.be/mnI-LiKCtuE?t=265 Seems I remembered it the wrong way round – it was the Corsa that held up and crumpled well enough to not have significant intrusion even at 110 km/h (70 mph).
        jsight 10y ago
        There was no engine in the front of that car.
        jads 10y ago
        This isn't really evidence that it's possible to make an engine that can crumple. In fact, quite the opposite. This particular Corsa B (93-2000) was a 1.4i (1.4L engine) - the physical dimensions of the engine are extremely small[1], and there is a lot of empty space in the engine bay that isn't taken up by the main engine block (excluding various plastics, wiring, etc - actual metal). I don't think it's so much the case that this engine "could crumple", rather that there was a lot of space for the front to crumple into, before there was none left and the engine was then pushed into the cabin. Engine blocks are, well, blocks of metal. They're not going to crumple in any meaningful way. [1]: http://iheartautos.co.za/wp-content/uploads/2015/09/engine-bay.jpg http://iheartautos.co.za/wp-content/uploads/2015/09/engine-b...
- agumonkey 10y ago
  Well the engine doesn't compress smoothly, it mostly translates into the cabin with high probability of partially crushing the people on the front seat. I believe Tesla layout just makes it 'easy' to let the frame dissipate energy internally by bending much more than any other ICE based cars.
- specialist 10y ago
  Ever do an egg drop? http://www.sciencekids.co.nz/projects/eggdrop.html http://www.sciencekids.co.nz/projects/eggdrop.html

by zelos 10y ago

creshal 10y ago

Sure, but how is an empty space better at absorbing impact energy than that?

codeduck 10y ago
Placing an engine in that empty space means that there is less space available for the car's crumple zones to deform before the engine intrudes into the passenger safety cell. A tesla can have its entire front concertina'd down to nothing without anything entering the safety cell. A front-engined normal car cannot do this; typically 50 to 60% of the length of the front of the car is engine. While external parts of the engine may crumple, the cylinder head and main section of the engine by necessity need to be milled from solid metal; These will not crumple, they will be pushed into the safety cell if the collision is energetic enough.
- jacquesm 10y ago
  In modern cars the design is such that the engine is pushed under the car if there is enough energy in the collision.
- ssmoot 10y ago
  In addition to the engine going under the vehicle (even at fairly low speed crashes; just watch NHSTA videos on YouTube), the front motor in a Model S is more dense and weighs about the same as a 4 cylinder engine, transmission and accessories. I'm gonna call that a wash until I see evidence to the contrary. Straight on collisions aren't even the toughest ones to pass. It's the small offset tests that really seem to give manufacturers a hard time. And no engine there.
DanBC 10y ago
When empty space gets pushed into the cabin it doesn't amputate legs. When an engine gets pushed into the cabin it might amputate legs.
- kerryfalk 10y ago
  This isn't what happens, though. As others have mentioned, the engine ends up under the car.
slaxman 10y ago
You want the front of the car to absrob the energy. When it crumples, it absorbs the energry and lesser energy is transferred to the passengers. The Engine is tough and will not crumple. It will thus not absorb the energy but transfer it to the passengers.
- creshal 10y ago
  And as I already mentioned before, this is simply not true, you can make engines that crumple extremely well.
  - CompelTechnic 10y ago
    Could you provide some evidence/ examples?
    - creshal 10y ago
      https://youtu.be/mnI-LiKCtuE?t=265 https://youtu.be/mnI-LiKCtuE?t=265 Seems I remembered it the wrong way round – it was the Corsa that held up and crumpled well enough to not have significant intrusion even at 110 km/h (70 mph).
      - jsight 10y ago
        There was no engine in the front of that car.
      - jads 10y ago
        This isn't really evidence that it's possible to make an engine that can crumple. In fact, quite the opposite. This particular Corsa B (93-2000) was a 1.4i (1.4L engine) - the physical dimensions of the engine are extremely small[1], and there is a lot of empty space in the engine bay that isn't taken up by the main engine block (excluding various plastics, wiring, etc - actual metal). I don't think it's so much the case that this engine "could crumple", rather that there was a lot of space for the front to crumple into, before there was none left and the engine was then pushed into the cabin. Engine blocks are, well, blocks of metal. They're not going to crumple in any meaningful way. [1]: http://iheartautos.co.za/wp-content/uploads/2015/09/engine-bay.jpg http://iheartautos.co.za/wp-content/uploads/2015/09/engine-b...
agumonkey 10y ago
Well the engine doesn't compress smoothly, it mostly translates into the cabin with high probability of partially crushing the people on the front seat. I believe Tesla layout just makes it 'easy' to let the frame dissipate energy internally by bending much more than any other ICE based cars.
specialist 10y ago
Ever do an egg drop? http://www.sciencekids.co.nz/projects/eggdrop.html http://www.sciencekids.co.nz/projects/eggdrop.html