for regular gas engines in either park or neutral? They say a typical car engine can idle for 50-70hours on a tank of gas so what do you think is the most effiienct one? I'll guess and say low compression ratio/turbo engines would be among the least efficient at idling and N/A high compression ones would be the most?
Which car/engine idles most efficiently
- Thread starter VinceVaughnce
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simple: 1st choice is electric, 2nd choice is hybrid.
I bet a new Kia Rio and it's Hyundai sibling would do really well.
I think that for a modern fuel-injected gasoline engine, the consumption at idle will be roughly proportional to the displacement. Per a ScanGauge OBD II reader, our old '97 Mazda MPV (3.0 litre SOHC) used 1.2 - 1.5 litres/hour, with 1.3 l/hr being typical. (That's about 1/3 US gallon/hour.) With the 74 litre tank, in theory the engine could have idled for 50 - 60 hours. This was in Park or Neutral; the engine will use more fuel idling in gear.
Fuel consumption at idle varies with air density (which is dependent on air temperature and elevation). (I saw the low of 1.2 l/hr in the mountains in the summer.) Fuel consumption will increase in denser (colder and/or closer to sea level) air, to keep the air/fuel ration constant.
Our '09 Mazda 5 (2.3 l DOHC VVT) uses about 0.6 - 0.8 l/hr. With a 60 l tank, that would allow for 75 - 100 hours of idling. It has a manual transmission, so of course this is in neutral.
A cold engine will use a lot more fuel of course, as it first runs in open loop, but I assume you're interested in consumption when the engine is warmed up.
An older carbureted engine would almost certainly use more fuel at idle than its FI counterpart.
Fuel consumption at idle varies with air density (which is dependent on air temperature and elevation). (I saw the low of 1.2 l/hr in the mountains in the summer.) Fuel consumption will increase in denser (colder and/or closer to sea level) air, to keep the air/fuel ration constant.
Our '09 Mazda 5 (2.3 l DOHC VVT) uses about 0.6 - 0.8 l/hr. With a 60 l tank, that would allow for 75 - 100 hours of idling. It has a manual transmission, so of course this is in neutral.
A cold engine will use a lot more fuel of course, as it first runs in open loop, but I assume you're interested in consumption when the engine is warmed up.
An older carbureted engine would almost certainly use more fuel at idle than its FI counterpart.
Originally Posted by Number_35
I think that for a modern fuel-injected gasoline engine, the consumption at idle will be roughly proportional to the displacement. ...
An older carbureted engine would almost certainly use more fuel at idle than its FI counterpart.
True about displacement. Idle speed is the other big factor.
I don't see why a healthy carbureted engine would necessarily be much different, if mixture is not set too rich.
I think that for a modern fuel-injected gasoline engine, the consumption at idle will be roughly proportional to the displacement. ...
An older carbureted engine would almost certainly use more fuel at idle than its FI counterpart.
True about displacement. Idle speed is the other big factor.
I don't see why a healthy carbureted engine would necessarily be much different, if mixture is not set too rich.
Originally Posted by VinceVaughnce
for regular gas engines in either park or neutral? They say a typical car engine can idle for 50-70hours on a tank of gas so what do you think is the most effiienct one? I'll guess and say low compression ratio/turbo engines would be among the least efficient at idling and N/A high compression ones would be the most?
Electric cars don't idle. It's been known for decades that the diesel engine at idle use about 25% fuel of a gas engine of same displacement
for regular gas engines in either park or neutral? They say a typical car engine can idle for 50-70hours on a tank of gas so what do you think is the most effiienct one? I'll guess and say low compression ratio/turbo engines would be among the least efficient at idling and N/A high compression ones would be the most?
Electric cars don't idle. It's been known for decades that the diesel engine at idle use about 25% fuel of a gas engine of same displacement
The ones that shut off at idle
Originally Posted by Linctex
Something with tiny cylinder head ports, a very low duration cam profile, and 17:1 compression.
This. Except we have to take into account the accessory loads. Mini-van with A/C on in Phoenix in summer ... Fish & Game truck on stake-out in winter with all radios and police net computer running ...
Is the cooling fan clutched, or in constant motion? Does it have day time driving lights, or no light load at all when parked?
Too many outside factors
Something with tiny cylinder head ports, a very low duration cam profile, and 17:1 compression.
This. Except we have to take into account the accessory loads. Mini-van with A/C on in Phoenix in summer ... Fish & Game truck on stake-out in winter with all radios and police net computer running ...
Is the cooling fan clutched, or in constant motion? Does it have day time driving lights, or no light load at all when parked?
Too many outside factors
Alternator load would be the only consideration..
Reason for asking specifically about regular gas engines is because someone mentioned being able to use your vehicle + inverter as an emergency power system when otherwise unprepared. There should seriously be a standardized rating for engine idle economy, but an analogous parameter to it might be idle CO2 emissions. A dedicated idle FE rating likely to never happen since current corporate strategy is to abandon the ICE...
Most people don't have electric cars which won't help past being a big battery, and diesels/hybrids are rare and generally not sought, so that's why it's gas engines only. In today's new world of relentless regular crises, plugging-in the emergency factor seems like a good idea when shopping for a vehicle. Funny how a lot of the car buying public obsess over the cup holders and dumb preloaded apps which won't help you a lick when youre stuck on a highway escaping a fire or trapped in a FREAK blizzard or when your power goes out for weeks.
Reason for asking specifically about regular gas engines is because someone mentioned being able to use your vehicle + inverter as an emergency power system when otherwise unprepared. There should seriously be a standardized rating for engine idle economy, but an analogous parameter to it might be idle CO2 emissions. A dedicated idle FE rating likely to never happen since current corporate strategy is to abandon the ICE...
Most people don't have electric cars which won't help past being a big battery, and diesels/hybrids are rare and generally not sought, so that's why it's gas engines only. In today's new world of relentless regular crises, plugging-in the emergency factor seems like a good idea when shopping for a vehicle. Funny how a lot of the car buying public obsess over the cup holders and dumb preloaded apps which won't help you a lick when youre stuck on a highway escaping a fire or trapped in a FREAK blizzard or when your power goes out for weeks.
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