Diesels are very efficent at idle?

[philmcneal]

I remember someone in the TDI fuel economy forum (tdiclub.com) telling me that when their diesels idle its way more efficent than a gasoline engine like mine idling in N. If that's the case, for a 1.7 liter like mine fully warmed up I waste around .8 liters (.21 gallons)/ hour. I wonder if their idling is much lower then it wouldn't make much sense to idle with no engine off if its really that efficent.

Damn not enough TDI'er trying to prove this theory!

[GasSavers_Brock]

bumping an old thread, but I have a TDI and once it’s warm at idle it consumes .2L per hour.

[philmcneal]

Originally Posted by Brock

bumping an old thread, but I have a TDI and once it’s warm at idle it consumes .2L per hour.

wow how long does it take for you to warm up? that's insane since it takes me .8L per hour fully warmed up when idling... man no wonder them diesels don't benifit much with an auto-stop feature

Originally Posted by CarloSW2

I'd feel bad wasting the gas too, but maybe you could attach a DC->AC inverter and "feed" the extra electricity load it is generating into your house. It wouldn't add much, but it wouldn't be going to waste either.

true but i'm too lazy to find that out.

[Rstb88]

jst buy an engine block heater for at home, or switch to ev so u don't have to worry about it..

[rh77]

Originally Posted by Rstb88

jst buy an engine block heater for at home, or switch to ev so u don't have to worry about it..

It's no big deal with the new technology. The "glow plugs" that allow cold starts have advanced in technology, so it'll be easier to start. If it's a Diesel-Hybrid and or plug-in more solutions would be available.

Also, to answer a previous question -- diesels last longer because they're built to withstand the very high compression ratios of the combustion (thicker blocks and sleeves within the cylinder).

RH77

[Ted Hart]

Originally Posted by rh77

Also, to answer a previous question -- diesels last longer because they're built to withstand the very high compression ratios of the combustion (thicker blocks and sleeves within the cylinder).

RH77

Correct! Plus (and it's a big plus!), diesel fuel is a lubricant. Oil is slicker than a solvent (gasoline). This makes a tremendous difference in wear rates!

[GasSavers_Brock]

I am with you I very very rarely idle for any lenth of time. I do have a 120vac coolant heater for winter. By the way using the coolant heater increases my MPG by about 10% on a 11 mile trip.

[GasSavers_Brock]

It takes FOREVER to warm up. Last winter when it was -10F or -23C with the front completely blocked driving on highway the engine temp never got above 150F and when I would slow down coming in to a town it would drop in to the 125F range. If you let it idle it will cool down, I never let it idle to long so I don't know how cold it might get. We have heated seat in the front and an electric blanket for the kids in the back.

I typically run a 120vac coolant heater when I am at home before I leave and when I leave it might be 190F and will drop to 160F by the time I am at work.

[Lug_Nut]

Diesels can have no throttle plate to reduce the airflow through the engine. Reducing the air volume (generating a manifold vacuum) will lower the amount of air in the cylinder to a point where compressing that reduced volume of air doesn't produce enough compression heat to ignite the fuel. At very low fuel use (idling for example) there is little fuel burned but a full volume of air moving that heat out the exhaust. As a result the engine coolant water jacket may not heat up. The engine is effectively internally air cooled.
It's not that the combustion is all that much more efficient, it's that the excess air takes too much heat away too quickly.

[GasSavers_BluEyes]

Originally Posted by Lug_Nut

Reducing the air volume (generating a manifold vacuum) will lower the amount of air in the cylinder to a point where compressing that reduced volume of air doesn't produce enough compression heat to ignite the fuel.

Tell that to my MB 220D! It's an old-tech diesel. The injector pump has a pnuematic governor and it has a throttle plate to generate manifold vacuum. One of the methods MB used to govern the engine speed on this one was to use a throttle limiter screw, so the throttle never even sees wide open.