How much gas to start a 3L or larger engine?

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I saw this Engineering Explained video a while ago: https://www.youtube.com/watch?v=dFImHhNwbJo The guy says that a small 4 cylinder engine will require about 7 seconds worth of gas while idling, to start that engine. His point was that if you have to stop for more than 7 seconds, it would save fuel simply to cut off the engine. I had a civic with a 4 cylinder 1.6 liter engine. Now, my cars have a 6--cylinder, 3.3L engine. I'm wondering how much gas would be required to start these engines, compared to idling time. Would it still be about 7 seconds? Would it be about 14 (assuming an engine twice as large, would require that much more gas to start)?
 
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You could prove this out the easiest with most any vehicle that has a, "Start / Stop" device. Drive it with a tankful with the system activated. Then fill up and drive again under the same conditions with the system disabled, and compare the results. Most all the new cars that have "Start / Stop" also have a average MPG computer. Regardless of how accurate it is or isn't, it will be accurate enough for direct comparison purposes. I'm willing to bet the difference is slight to immeasurable.
 
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Originally Posted by billt460
You could prove this out the easiest with most any vehicle that has a, "Start / Stop" device. Drive it with a tankful with the system activated. Then fill up and drive again under the same conditions with the system disabled, and compare the results. Most all the new cars that have "Start / Stop" also have a average MPG computer. Regardless of how accurate it is or isn't, it will be accurate enough for direct comparison purposes. I'm willing to bet the difference is slight to immeasurable.
I agree, slight to immeasurable fuel savings. Factoring in the annoyance factor, I'd make sure I disable it every time I drive if I owned a vehicle equipped with it.
 
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I rented a Kia Soul with start stop. It was done SO WELL that I didn't find it annoying at all. I have to believe it save quite a bit or they wouldn't do it.
 
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This is one of many things that make me unhappy with new cars.. Aero headliights that cost $100 to ???? that will save maybe 25 gallons of gas over the life of the vehicle. 8,9,10 speed transmissions that will cost $3000 and up(mostly up) to rebuild, that can save you a whopping 1000 dollars of gas (27 ro 29 MPG) vs a 4 speed that costs 1500 to 2000 electric power steering that save maybe 200 dollars of fuel and $1000 and up to repair and do not drive like I am used to. large diameter wheels that ride worse and tire cost is thru the roof. Air bags in the seat that make fixing a simple rip cost $$$$ OHC to get big horsepower numbers and a belt change costs 500 and replace chain setup and guides is 2000 and up. And seems they always drip oil after that. Direct injectors start stop starters. LED headlights. Plastic everywhere that splits after a few years. This list goes on and on and on. Rod
 
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Meanwhile, back at the ranch.... I was asking about how much fuel (in terms of seconds of idling) it took to start larger motors.
 
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Originally Posted by billt460
I'm willing to bet the difference is slight to immeasurable.
I beg to differ. With a scanner plugged into the port, you can see exactly how much fuel the engine is using. There's a *HUGE* difference in fuel usage between idling in "Neutral" and idling in "Drive" - sometimes a gallon or more burned per tank. I think vehicle manufacturers would see more savings with "auto neutral" at a stoplight than "start/stop" honestly
 
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Originally Posted by ragtoplvr
This is one of many things that make me unhappy with new cars.. 8,9,10 speed transmissions that will cost $3000 and up(mostly up) to rebuild, that can save you a whopping 1000 dollars of gas (27 ro 29 MPG) vs a 4 speed that costs 1500 to 2000 electric power steering that save maybe 200 dollars of fuel and $1000 and up to repair and do not drive like I am used to. large diameter wheels that ride worse and tire cost is thru the roof. This list goes on and on and on.
I AGREE, ROD. IT'S INSANE - but the vehicle manufactures have to meet the "magic number" - - - - and pass the costs on to us. I have the same peeve with weedeaters, blowers, other small OPE, etc...... Most of these burn maybe 5 -10 gallon of gas their whole entire lifetime! (average homeowner) Yet, due to emissions controls - - - they often end up in the trash long before they should have expired. No one wants to talk about all the emissions from manufacturing them in the first place, or the waste/cost of disposal...............
 
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Originally Posted by Linctex
Originally Posted by billt460
I'm willing to bet the difference is slight to immeasurable.
I beg to differ. With a scanner plugged into the port, you can see exactly how much fuel the engine is using. There's a *HUGE* difference in fuel usage between idling in "Neutral" and idling in "Drive" - sometimes a gallon or more burned per tank. I think vehicle manufacturers would see more savings with "auto neutral" at a stoplight than "start/stop" honestly
When the engine is in drive it is under a load. Slight, but a load none the less. So naturally it is going to use more gas than if it's free wheeling in neutral. I shift into neutral during long lights to save transmission wear, not gas. I agree with you that "Auto Neutral" makes more sense from a fuel saving standpoint, than "Auto Start / Stop". The problem with it is how would it know when to engage back into drive? If it waited until the driver demand it with throttle input, it would be constantly neutral dropping the transmission. It would require a, "fly by wire" accelerator that was run through the computer and brake pedal. Still more expensive complexity to save a few drops of gas.
 

Pew

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962
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Illinois
Originally Posted by billt460
You could prove this out the easiest with most any vehicle that has a, "Start / Stop" device. Drive it with a tankful with the system activated. Then fill up and drive again under the same conditions with the system disabled, and compare the results. Most all the new cars that have "Start / Stop" also have a average MPG computer. Regardless of how accurate it is or isn't, it will be accurate enough for direct comparison purposes. I'm willing to bet the difference is slight to immeasurable.
It was "noticeable" in my ford focus, but you have to be actively measuring in order to see the difference. Most people won't but the savings isn't like it's going to make or break a record.
 
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Chicagoland
Originally Posted by billt460
The problem with it is how would it know when to engage back into drive? If it waited until the driver demand it with throttle input, it would be constantly neutral dropping the transmission. It would require a, "fly by wire" accelerator that was run through the computer and brake pedal. Still more expensive complexity to save a few drops of gas.
Most, if not all, cars with traction control use fly by wire accelerators.
Originally Posted by ragtoplvr
This is one of many things that make me unhappy with new cars.. Aero headliights that cost $100 to ???? that will save maybe 25 gallons of gas over the life of the vehicle. 8,9,10 speed transmissions that will cost $3000 and up(mostly up) to rebuild, that can save you a whopping 1000 dollars of gas (27 ro 29 MPG) vs a 4 speed that costs 1500 to 2000 electric power steering that save maybe 200 dollars of fuel and $1000 and up to repair and do not drive like I am used to. large diameter wheels that ride worse and tire cost is thru the roof. Air bags in the seat that make fixing a simple rip cost $$$$ OHC to get big horsepower numbers and a belt change costs 500 and replace chain setup and guides is 2000 and up. And seems they always drip oil after that. Direct injectors start stop starters. LED headlights. Plastic everywhere that splits after a few years. This list goes on and on and on. Rod
I can buy a new OEM 8 speed transmission for my Chrysler 300 for $2,608.20, which includes a new torque converter. I'll gladly pay $608.20 extra for a NEW transmission vs $2,000 to rebuild some inferior 4 speed slush box.
 
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With these conversations I think we should also factor in the additional wear and tear on the starter motor, battery, ignition switch, key lock, etc. I understand these would be very hard to factor in and maybe miniscule costs in the long-term, but also we are talking about the "cost" of idling an engine for 7 seconds, so...
 
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Are we? That was for a small four cylinder engine. I was wondering how much time it would take to start up a larger engine.
Originally Posted by DGXR
but also we are talking about the "cost" of idling an engine for 7 seconds, so...
 
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