A proper language comparison...

[Andrei Alexandrescu]

On 7/26/13 4:25 PM, Walter Bright wrote:
> On 7/26/2013 4:07 PM, Andrei Alexandrescu wrote:
>> On 7/26/13 3:52 PM, Walter Bright wrote:
>>> Although commonplace, it is poor practice to use the engine to slow the
>>> car down (unless you're dealing with brake fade from overheating).
>>
>> I know next to nothing about cars so take this destruction with a
>> grain of salt.
>>
>>> 1. Brake pads are cheap compared with engine rebuilds.
>>
>> My understanding is that engine brake does not destroy the engine. It
>> does not
>> involve friction.
>
> It's news to me that engines are frictionless! (The braking effect is
> only partially due to engine friction - the pumping of the air is most
> of it. But the engine WEAR is due to friction.)
>
>> Indeed Wikipedia agrees:
>> http://en.wikipedia.org/wiki/Engine_braking and even mentions "Engine
>> braking is
>> a generally accepted practice and can help save wear on friction brakes".
>
> Of course it saves wear on the brakes. The issue is do you prefer wear
> on your engine?
>
>
>>> 2. Using the engine as a brake can cause unburned gas to wash the oil
>>> off of the cylinder walls, resulting in excessive wear.
>>
>> [citation needed]
>
> Mechanics at the dealer told me this. They had no reason to lie to me.
>
>
>>> 3. The engine is not designed to be a brake. Use the brakes. Brake pads
>>> are not precious :-)
>>
>> Engine brake is a natural artifact of its design. I don't think you
>> can build an
>> argument around "wasn't design to do that, so don't". Engine braking is a
>> widespread and common technique.
>
> I agree it is widespread and commonplace. That's why the mechanics felt
> it necessary to tell me not to do it. I was also told not to do it when
> I took two different courses in track driving - the Bob Bondurant and
> Skip Barber ones.
>
>
>> I use engine braking most of the time (I always drive manual so that's
>> easy).
>> Saves gas and I've never had a mechanic tell me "you better go easy
>> with that
>> engine brake, look at them cylinder walls!" My brake pads reach a
>> state of
>> immortality.
>
> The object isn't to save brake pads, it's to reduce the wear and tear on
> your engine.

I stand by my opinion and practice, and I consider yours completely 
unsubstantiated, to the extent it doesn't need further rebuttal. FWIW 
I've heard stuff from mechanics (about e.g. how ABS works) that would 
make a physicist blush.

Andrei