6 ms·

With stick shift cars you can use the engine to brake and get the same brake pad savings

thfuran 7y ago
You can but very few people drive stick in the US and, of those, I suspect very few use engine breaking for a significant fraction of their braking. For getting off a highway maybe, but probably not for stop and go in a city.
- paulie_a 7y ago
  In fact engine breaking is illegal in most populated areas
  - jandrese 7y ago
    This is not true. There are specific areas that ban it and have signage alerting drivers to that fact, but it is not common. Plus, it typically only applies to Semis as their engine braking is especially noisy. On a typical gas powered sedan you would be hard pressed to identify that someone is engine braking unless you were right next to it. Being prosecuted for it would be even more exceptional.
  - organsnyder 7y ago
    That kind of engine braking (the kind trucks do that's extremely loud) is completely different from "engine braking" with the transmission
  - macintux 7y ago
    This is the braking that communities post signage about: https://en.wikipedia.org/wiki/Compression_release_engine_brake https://en.wikipedia.org/wiki/Compression_release_engine_bra...
mikestew 7y ago
...at the expense of piston rings and other expensive, hard-to-get-to items. And, an educated guess here, probably increased emissions on the overrun. Besides, who drives stick anymore? I've driven stick since I learned to drive forty years ago, and I even I admit that I can't do better than a computer-controlled DCT, on performance or fuel efficiency. Next car is either electric (we already have a Leaf), or DCT if we must.
- RcouF1uZ4gsC 7y ago
  > ...at the expense of piston rings and other expensive, hard-to-get-to items. And, an educated guess here, probably increased emissions on the overrun. This seems like a bad tradeoff. Increasing wear on expensive, hard to replace parts (your engine and transmission), so that you can save on relatively inexpensive, easy to replace parts (your brake pads)
  - inferiorhuman 7y ago
    This seems like a bad tradeoff. Increasing wear on expensive, hard to replace parts (your engine and transmission), so that you can save on relatively inexpensive, easy to replace parts (your brake pads) So that's not actually the tradeoff you're making. More to the point you run a much higher risk of acute failure with brakes than with anything else. When that happens on a downgrade you can't stop. If you were actually increasing wear on piston rings (a laughable argument at best) you might end up needing to rebuild the engine after a few decades.
- kovach 7y ago
  There are no fuel emissions when you engine brake in a modern fuel injection vehicle, as fuel intake is stopped [1]. But it could be bad for your piston rings and catalytic converter [2], so there's that... [1] https://en.wikipedia.org/wiki/Engine_braking#Gasoline_engines https://en.wikipedia.org/wiki/Engine_braking#Gasoline_engine... [2] https://ricksfreeautorepairadvice.com/engine-braking-cause-damage/ https://ricksfreeautorepairadvice.com/engine-braking-cause-d...
  - inferiorhuman 7y ago
    Good lord Rick's Free Auto Repair Advice is worth what you paid for it. Compression brakes (of which Jacobs is one brand) actually do increase top end wear on a diesel quite a bit. What Rick is prattling on about might have been an issue in the 60s when engines would be well worn by 100,000 miles and PCV was not a thing. These days you're sucking crankcase gasses right into the combustion chamber constantly thanks to what's known as positive crankcase ventilation. Typically when you see a puff of smoke after overrun that's an indication of bad valve guides more than anything else (also not a common occurrence these days). Oil in your catalytic converter isn't good, but that's why you have one or more spark plugs per cylinder — to burn it. There's the issue of heavy metals in the oil (e.g. zinc – generally in the form of ZDDP) that can damage your cat, sure, but that's why the current API specs have reduced the amount of allowable zinc a revision or so ago (API SN or SM I believe). Zinc is a great anti-wear additive but in high enough concentration can damage your cat. Stop and go traffic will wear your clutch out (assuming we're talking cars with dry plate clutches here and not a motorcycle or anything else with a wet clutch). Engine braking will not (assuming you're not riding the brakes or constantly shifting while trying to slow down). Hell, even if you are downshifting needlessly if you're rev matching you're not wearing the clutch all that much. I'll take this fictitious clutch wear over acute brake failure thank you very much. In fact I've yet to destroy a cat or clutch in San Francisco traffic.
PeterStuer 7y ago
Or just use the Cruise Control speed toggle on your automatic. At least on mine (BMW) it engages regenerative breaking when you click down the speed.

You can but very few people drive stick in the US and, of those, I suspect very few use engine breaking for a significant fraction of their braking. For getting off a highway maybe, but probably not for stop and go in a city.

paulie_a 7y ago
In fact engine breaking is illegal in most populated areas
- jandrese 7y ago
  This is not true. There are specific areas that ban it and have signage alerting drivers to that fact, but it is not common. Plus, it typically only applies to Semis as their engine braking is especially noisy. On a typical gas powered sedan you would be hard pressed to identify that someone is engine braking unless you were right next to it. Being prosecuted for it would be even more exceptional.
- organsnyder 7y ago
  That kind of engine braking (the kind trucks do that's extremely loud) is completely different from "engine braking" with the transmission
- macintux 7y ago
  This is the braking that communities post signage about: https://en.wikipedia.org/wiki/Compression_release_engine_brake https://en.wikipedia.org/wiki/Compression_release_engine_bra...

mikestew 7y ago

...at the expense of piston rings and other expensive, hard-to-get-to items. And, an educated guess here, probably increased emissions on the overrun. Besides, who drives stick anymore? I've driven stick since I learned to drive forty years ago, and I even I admit that I can't do better than a computer-controlled DCT, on performance or fuel efficiency. Next car is either electric (we already have a Leaf), or DCT if we must.

RcouF1uZ4gsC 7y ago
> ...at the expense of piston rings and other expensive, hard-to-get-to items. And, an educated guess here, probably increased emissions on the overrun. This seems like a bad tradeoff. Increasing wear on expensive, hard to replace parts (your engine and transmission), so that you can save on relatively inexpensive, easy to replace parts (your brake pads)
- inferiorhuman 7y ago
  This seems like a bad tradeoff. Increasing wear on expensive, hard to replace parts (your engine and transmission), so that you can save on relatively inexpensive, easy to replace parts (your brake pads) So that's not actually the tradeoff you're making. More to the point you run a much higher risk of acute failure with brakes than with anything else. When that happens on a downgrade you can't stop. If you were actually increasing wear on piston rings (a laughable argument at best) you might end up needing to rebuild the engine after a few decades.
kovach 7y ago
There are no fuel emissions when you engine brake in a modern fuel injection vehicle, as fuel intake is stopped [1]. But it could be bad for your piston rings and catalytic converter [2], so there's that... [1] https://en.wikipedia.org/wiki/Engine_braking#Gasoline_engines https://en.wikipedia.org/wiki/Engine_braking#Gasoline_engine... [2] https://ricksfreeautorepairadvice.com/engine-braking-cause-damage/ https://ricksfreeautorepairadvice.com/engine-braking-cause-d...
- inferiorhuman 7y ago
  Good lord Rick's Free Auto Repair Advice is worth what you paid for it. Compression brakes (of which Jacobs is one brand) actually do increase top end wear on a diesel quite a bit. What Rick is prattling on about might have been an issue in the 60s when engines would be well worn by 100,000 miles and PCV was not a thing. These days you're sucking crankcase gasses right into the combustion chamber constantly thanks to what's known as positive crankcase ventilation. Typically when you see a puff of smoke after overrun that's an indication of bad valve guides more than anything else (also not a common occurrence these days). Oil in your catalytic converter isn't good, but that's why you have one or more spark plugs per cylinder — to burn it. There's the issue of heavy metals in the oil (e.g. zinc – generally in the form of ZDDP) that can damage your cat, sure, but that's why the current API specs have reduced the amount of allowable zinc a revision or so ago (API SN or SM I believe). Zinc is a great anti-wear additive but in high enough concentration can damage your cat. Stop and go traffic will wear your clutch out (assuming we're talking cars with dry plate clutches here and not a motorcycle or anything else with a wet clutch). Engine braking will not (assuming you're not riding the brakes or constantly shifting while trying to slow down). Hell, even if you are downshifting needlessly if you're rev matching you're not wearing the clutch all that much. I'll take this fictitious clutch wear over acute brake failure thank you very much. In fact I've yet to destroy a cat or clutch in San Francisco traffic.

PeterStuer 7y ago

Or just use the Cruise Control speed toggle on your automatic. At least on mine (BMW) it engages regenerative breaking when you click down the speed.