City driving econ: Faster accel in lower gears vs. Slower accel in higher gears?

[Piwoslaw]

That reminds me of the Russiann truck drivers, who reportedly light small fires under their engines to keep them from cooling down when they stop for the night in -40 deg temperatures.

[Logic]

Originally Posted by cRiPpLe_rOoStEr

Engine block heaters are mostly unheard of in my country, yet some folks used to place an electric water heater inside the radiator and keep it plugged for a while to ease cold starts in some regions.

Yep; there's already been discussion here somewhere on kits one can buy and how best to do this.
IIRC besides a 'kettle element' and thermostat switch, an electric pump is required and plumbing into the pipes that go to/from the interior heater is easiest..?

[Logic]

The wonders of an adjustable vacuum switch:
(especially for small engined cars)

When you accelerate you open a throttle valve/s in the engine air intake.
When you brake, your foot is off the gas and that throttle valve is closed.
The engine's rotational momentum pulls a large vacuum between the intake valves and throttle valve.
Enough to power your brake assist booster.
ie:
Whenever you lift off the accelerator and have excess momentum=free power; there's this vacuum. The vacuum will remain/persist if you gear down when slowing, which turns forward momentum into rotational momentum which can/will turn your alternator and aircon pump with free power...

So; you can use this LACK of vacuum during acceleration and an adjustable vacuum switch to auto shut off power to your car's alternator and/or aircon pump while accelerating
and
auto turn them on again when slowing/gearing down and braking.
The 'adjust' lets set when they come on so they don't remain off at cruise.

NB that the above can easily get an auto override so the battery continues charging as usual if its too flat
and the aircon remains on if its too hot.
Adding that too a/the simple circuit diagram is easy with a voltage sensor switch and thermostat switch.
(The 'econ' setting on aicons may already do this to the aircon pump nowadays?? I need to look that up)

The same system can be used to 'auto hot air intake' (economy) at cruise and slowdown and 'auto cool power!' during acceleration.

These have likely been discussed here often. IIRC aerohead does this?

The vacuum takeoff pipe that goes to the brake booster is existent and thinner and most likely easier to T into for said vacuum switch.
Various other switches (interior thermostat, battery level) are most likely also existent.

[cRiPpLe_rOoStEr]

Originally Posted by Logic

IIRC besides a 'kettle element' and thermostat switch, an electric pump is required and plumbing into the pipes that go to/from the interior heater is easiest..?

Maybe it would take longer without an electric pump, but it worked...

[Piotrsko]

Originally Posted by Logic

The wonders of an adjustable vacuum switch:
(especially for small engined cars)

When you accelerate you open a throttle valve/s in the engine air intake.
.

Nice, but I own diesels. No throttle plate required.

[Logic]

Originally Posted by Piotrsko

Nice, but I own diesels. No throttle plate required.

Good point! WhereTH do diesels get vacuum for brake assist from?

Pumps and hydraulics apparently.

So... how do modern diesel engines know when the engine's in overrun?
But do NB this thread is for a gas engine before we hijack it!

[Piotrsko]

Over run was done by a fuel govenor that shut off fuel progressively that faster it turned. Doesn't really stop overrun, particularly downhill.
Two systems for power add-ons: vacuum or hydraulic. Brakes, steering on a F250 are from the steering pump , AC selection is vacuum, but my schoolbus had a pot load of vacuum powered stuff so it had a pump.

[Caddylackn]

Volkswagen TDIs use a vacuum pump driven off the camshaft.

They use the vacuum for power brakes and for the N75 valve to control either:
max. boost via the wastegate of the turbocharger (older TDIs)
or
changing the angle of the vanes in the VNT turbocharger (variable nozzle turbocharger)

[cRiPpLe_rOoStEr]

Originally Posted by Piotrsko

Nice, but I own diesels. No throttle plate required.

I guess you know about that Fiat GSE Multiair engine which has been fitted to the Jeep Renegade. It has only kept the throttle plate as a source for vacuum to the brake booster. Throttling properly said is controlled by the variable timing of the intake valves, actuated hydraulically instead of by a camshaft.

[Logic]

Originally Posted by cRiPpLe_rOoStEr

I guess you know about that Fiat GSE Multiair engine which has been fitted to the Jeep Renegade. It has only kept the throttle plate as a source for vacuum to the brake booster. Throttling properly said is controlled by the variable timing of the intake valves, actuated hydraulically instead of by a camshaft.

So it has a normally open throttle valve just to charge vacuum powered ancillaries during overrun and braking/ (free power)

I can see it getting hydraulic pressure to actuate, from the same pump that actuates the VVT, but, at a guess I'd say there's a torque sensor or 2 in the drive-train somewhere that picks up torque coming from the wheels and/or flywheel during overrun..?
Probably a braking sensor, involved in decisions to..?
The above discussed circuit would work off a torques sensor.
I must remember to research this.