Engine On 'n Off

<div class='quotetop'>QUOTE(Stev0 @ Jun 7 2007, 09:47 PM) [snapback]457768[/snapback]</div>

Part of the answer is that the engine is turning (causing lubrication) but the valves are open (not causing combustion). Now the technically inclined can supply a more complete and accurate answer.

 

<div class='quotetop'>QUOTE(Stev0 @ Jun 7 2007, 10:47 PM) [snapback]457768[/snapback]</div>

Why would you know the answer for that ? it's really not common knowledge.

There's plenty of threads on how the engine (ICE) works.

In short and quoted from wiki "The frequent starting and stopping of the engine does not cause additional wear and tear or emission problems because the drive motors have enough power to quickly spin the engine to optimal rpm (around 1,000) before the engine fires up. This avoids the wear that would occur if the engine were to run (with fuel and spark) at very low rpm."




I

 

In addition to the previously stated, I'm under the impression that the wear and tear on engines is most significant on cold start ups.

 

i heard starting an engine takes as much gas as it would be running for a minute. is it not true, or just different with a prius?

 

<div class='quotetop'>QUOTE(YodaddyAlex @ Jun 9 2007, 09:42 AM) [snapback]458383[/snapback]</div>

We see about 1 cc (0.000264 gallon) consumption when Prius engine starts.
Driving 30 mph at 50 mpg, Prius consumes 37.85 cc (0.01 gallon) per minutes.

Ken@Japan

 

<div class='quotetop'>QUOTE(efusco @ Jun 8 2007, 10:09 PM) [snapback]458476[/snapback]</div>

And to think, our now-defunct electric chair never pumped more than about eight amps through the miscreants it had to dispatch. I suppose there's a good reason why those thick cables are colored bright orange...

Seriously though, yes, the way the MGs spin up the engine before it lights off is akin to the function of the pre-oilers you can install on a conventional car to reduce wear on a cold start. Amsoil sells a kit for about $250 IIRC. You'd never need such a contraption for a Prius; I doubt its bearings ever see a load without solid oil pressure already there to keep things separated.

 

Tony, your answer is still good, just not detailed. If you started a conventional car as often as a Prius starts its ICE, I'm not sure the battery or engine would last a year.

 

<div class='quotetop'>QUOTE(efusco @ Jun 9 2007, 12:09 PM) [snapback]458476[/snapback]</div>

We've never seen such 200 A usage. The Prius battery is rated 21 kW which means about 100 A max.

Just FYI, following chart is an actual data using PCM CAN data logger for 4 seconds engine on.
The X axis (horizontal) unit is 0.1 second, so it shows 10 seconds duration.

0-10:0-1.0 sec:gas pedal off regenerating, about 3.5 A charge
11-25:1.1-2.5 sec:gas pedal on, EV mode accelerating.
26-30:2.6-3.0 sec:engine starting:max is 54.3 A.
31-74:3.1-7.4 sec:engine on, charging 4-14 A.
75-104:7.5-10.4 sec:engine off, EV mode driving, about 3 A discharge.

The total fuel consumption is 3 cc.

Ken@Japan

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