Re: Speed limiters

Jeff Layman <Jeff@invalid.invalid> wrote:

On 07/07/2024 23:51, KevinJ93 wrote:

On 7/7/24 9:57 AM, Don Y wrote:

 

In The West, it is not uncommon to find yourself driving through varying
elevations (mountains).  Relying solely on the engine for braking often
won't allow you to comply with the posted speed limits *or* "safe driving
conditions".
 
[OTOH, being overly reliant on the brake can lead to brake overheating and
failure]

 
My recent cars automatically increase engine RPM by changing gear to
maximize engine braking, in addition to using brakes if necessary.
 
Some people find that disturbing to have the engine spinning at
4000-5000RPM down steep hills.

 
A few years after I learned to drive (in 1972!) I was in England's Lake
District which has some long and pretty steep hills. Coming down one in
my manually-geared car I decided I could save petrol by turning the
engine off and leaving the car in second gear, using the aid of engine
braking to save heavy use of the brakes. What I'd forgotten is that the
fuel pump wasn't electric, but was driven off the engine shaft. So as
the engine braking was rotating the shaft all the way down, at the end
of the run not only hadn't I saved any fuel but I'd flooded the
cylinders as well and the engine wouldn't restart until all the excess
fuel had been expelled!
 

You were lucky—if you’d bump started it successfully, you’d have blown the
exhaust right off the car.

Turning off the ignition for a few seconds inside a tunnel was a popular
stunt BITD—made a lovely bang. ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics