3 ms·

As well as all cars with manual transmissions.

sandworm101 7y ago
"Engine braking" isn't just letting the engine spin down at 0 throttle. Propper engine braking, aka "Jake brake", is letting the engine spin at 100% throttle but zero fuel input (and some valve trickery). This lets air in to be compressed, releasing it before the down stroke of the piston. No car does that. It is a separate installed system on trucks. It can be almost as powerful as the engine. In a car, it could handle all but emergency braking. https://en.m.wikipedia.org/wiki/Compression_release_engine_brake https://en.m.wikipedia.org/wiki/Compression_release_engine_b... When you hear a truck making popping noises like a machine gun, that's the Jake brake in action.
- hamandcheese 7y ago
  > Engine braking occurs when the retarding forces within an engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes. > The term is often confused with several other types of braking, most notably compression-release braking or "jake braking" which uses a different mechanism. https://en.m.wikipedia.org/wiki/Engine_braking https://en.m.wikipedia.org/wiki/Engine_braking
  - sandworm101 7y ago
    But when you see a sign saying "no engine braking" it refers to the jake brake, not down-shifting in a car. (It's a long trademark story over the use of "jake")
- saiya-jin 7y ago
  I have on my manual 15-year old diesel bmw very much an engine brake. It breaks quite well compared to neutral which seems to like to go on forever, and actually indicates proper consumption. On highways and motorways, I rarely need to use brake at all. Of course, being a sensible driver helps (in contrary to what many people expect from me when they see the car and expect yet another immature aggressive driver)
- ironmagma 7y ago
  Is this (jake brake) what the parent comment was referring to that newer automatics finally do?
  - sandworm101 7y ago
    Nope. That was reference to automatic transmissions not up shifting immediately every time you decrease throttle.
    - ironmagma 7y ago
      Why do they upshift when throttle is decreased? Wouldn’t it make more sense to downshift since the driver is probably about to brake?
- fyfy18 7y ago
  Maybe not exactly the same, but the B mode on hybrid cars sound similar. When you are driving down a large hill (e.g. on a mountain) eventually the battery will become fully charged, so you can't use regenerative braking anymore. To provide some resistance so you aren't effectively driving in neutral, the car will spin the engine at high RPM without supplying any fuel (I'm not sure how this works in terms of lubrication, as I understand the fuel provides this too?). You can also engage B mode which does this at an earlier stage, so have more control without having to use the brake when driving down steep hills (like engaging a lower gear). London hybrid busses do the same thing, as they come to a stop you can hear the engine spinning at high RPMs.

"Engine braking" isn't just letting the engine spin down at 0 throttle. Propper engine braking, aka "Jake brake", is letting the engine spin at 100% throttle but zero fuel input (and some valve trickery). This lets air in to be compressed, releasing it before the down stroke of the piston. No car does that. It is a separate installed system on trucks. It can be almost as powerful as the engine. In a car, it could handle all but emergency braking. https://en.m.wikipedia.org/wiki/Compression_release_engine_brake https://en.m.wikipedia.org/wiki/Compression_release_engine_b... When you hear a truck making popping noises like a machine gun, that's the Jake brake in action.

hamandcheese 7y ago
> Engine braking occurs when the retarding forces within an engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes. > The term is often confused with several other types of braking, most notably compression-release braking or "jake braking" which uses a different mechanism. https://en.m.wikipedia.org/wiki/Engine_braking https://en.m.wikipedia.org/wiki/Engine_braking
- sandworm101 7y ago
  But when you see a sign saying "no engine braking" it refers to the jake brake, not down-shifting in a car. (It's a long trademark story over the use of "jake")
saiya-jin 7y ago
I have on my manual 15-year old diesel bmw very much an engine brake. It breaks quite well compared to neutral which seems to like to go on forever, and actually indicates proper consumption. On highways and motorways, I rarely need to use brake at all. Of course, being a sensible driver helps (in contrary to what many people expect from me when they see the car and expect yet another immature aggressive driver)
ironmagma 7y ago
Is this (jake brake) what the parent comment was referring to that newer automatics finally do?
- sandworm101 7y ago
  Nope. That was reference to automatic transmissions not up shifting immediately every time you decrease throttle.
  - ironmagma 7y ago
    Why do they upshift when throttle is decreased? Wouldn’t it make more sense to downshift since the driver is probably about to brake?
fyfy18 7y ago
Maybe not exactly the same, but the B mode on hybrid cars sound similar. When you are driving down a large hill (e.g. on a mountain) eventually the battery will become fully charged, so you can't use regenerative braking anymore. To provide some resistance so you aren't effectively driving in neutral, the car will spin the engine at high RPM without supplying any fuel (I'm not sure how this works in terms of lubrication, as I understand the fuel provides this too?). You can also engage B mode which does this at an earlier stage, so have more control without having to use the brake when driving down steep hills (like engaging a lower gear). London hybrid busses do the same thing, as they come to a stop you can hear the engine spinning at high RPMs.