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I read that the engineers were having problems with rough/noisy switching from electric to gas mode, (and back?). Perhaps they will use the larger engine with an atkinson cycle and less compression.
 

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I still think that the engine should be kept as small as possible. I don't know the specs of either engine and I don't know how well they perform but if the 1.0L turbo is sufficient stick with that. There is no need for a large engine is the smaller one can do the job.

A larger 4 cylinder engine increases weight and mechanical components and fuel consumption. These increases are likely to be fairly minimal but I also think that the power output gained is minimal.
 

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Well "IF" all the rumors are true this isn't looking to good...

A model with a 20 mile battery range AND a 4 cylinder 1.4L engine. Why even bother?

It sounds to me like GM is trying to kill this thing before they even try and sell it.

Déjà vu, anyone?
 

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I still think that the engine should be kept as small as possible. I don't know the specs of either engine and I don't know how well they perform but if the 1.0L turbo is sufficient stick with that. There is no need for a large engine is the smaller one can do the job.

A larger 4 cylinder engine increases weight and mechanical components and fuel consumption. These increases are likely to be fairly minimal but I also think that the power output gained is minimal.

I run classic Minis (not the BMW new MINI). A Mini with the standard 1.0L engine will plod along all day, though it won't be a particularly exciting drive (a turbo might make things more interesting). I can't imagine anything near that size being necessary for simply recharging a battery pack.

I personally prefer my Minis to have the 1.3L engine. Which is a different story altogether when it comes to power. But then we're talking about a drivetrain, not a battery charger.

Remember too that Fiat powered their original Cinquecento on only .5L!
 

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lostngone wrote: “A model with a 20 mile battery range AND a 4 cylinder 1.4L engine. Why even bother?”

The Volt was originally designed as a commuter running mostly on the stored electrical energy. The 1000cc range extender ICE is there just in case and certainly is not powerful enough to motivate the heavy body (ICE + electric motor + battery pack) on freeways especially when going uphill with empty battery pack. If GM is putting a larger ICE to satisfy wider audience I think it is killing the original “excellent” concept. As losngone said, why bother? Has GM found out the brilliance of the Prius design only now?
 

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Bettery Battery Discharge?

Here is a thought:

Let's suppose that during testing of the battery packs, it become clear that they will be able to extend the depth of discharge below the original 30% DOD.

As a result they will be able to downsize the battery pack (lower costs) while at the same time keeping the range the same.

Now the disadvantage of doing this is if the car was in strenuous driving while the battery was at the bottom of it's charge there is a risk of the car losing power.

Solution: Increase the size of the generator to compensate.
 

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lostngone wrote: “A model with a 20 mile battery range AND a 4 cylinder 1.4L engine. Why even bother?”

The Volt was originally designed as a commuter running mostly on the stored electrical energy. The 1000cc range extender ICE is there just in case and certainly is not powerful enough to motivate the heavy body (ICE + electric motor + battery pack) on freeways especially when going uphill with empty battery pack. If GM is putting a larger ICE to satisfy wider audience I think it is killing the original “excellent” concept. As losngone said, why bother? Has GM found out the brilliance of the Prius design only now?
The size of the ICE does not make any difference to the way the vehicle will perform with a dead battery. You are thinking like it WAS a Prius. The size of the generator that the ICE turns will decide the performance. A 20 kW generator will keep the car running at 60 MPH untill you run out of gas. A 40 kW generator will run the car at 60 MPH and recharge the pack in 3.5 hours at the same time. GM wants to put a 53kW generator in the Volt? WHY? A 250CC motorcycle engine will run a 15 kW cont/20 kW peek generator. Three minutes at a stop light should put enough power back into the battery pack to give you the 0-60 spec of the vehicle with fully charged batteries. Sounds like overkill to me.
 

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Sorry, the size of ICE does make a big difference. You cannot get something out of nothing. For a generator to produce a required amount of electrical power the ICE that drives it should have slightly more mechanical power because of the loss incurred in the process of energy conversion.

I hope you agree that we need at least 100HP or 75KW of power to move a 3500Lb car uphill at a “decent” speed with some reserve. GM’s smallest car Aveo, which weighs 2531Lbs, is rated at 103HP or 77KW, for example.

Now, let’s take a look at the Volt specs. Its electrical power is rated at 45KW constant and 53KW peak. This should be OK for driving on flat city streets to commute, but certainly is not enough to keep up with 150HP “family” cars running side-by-side up the Tejon pass on the I-5. The only way to improve performance of the Volt in this case is to increase the power rating of the driving motor, to as much as 100KW. I do not know whether this is practical or not. However, the fact GM is contemplating increasing the output power of the ICE means it intends to increase the output power of the driving motor. In the serial hybrid design the output of the ICE should be somewhat higher than the output of the driving motor if you want to maintain the “decent” performance, since it has to power the generator which supplies current to both driving motor and battery pack (when the battery pack is depleted). Suppose the output power of driving motor is 75KW, you need as much as 80KW or 107HP generated at the ICE, thence the requirement for 1400cc displacement rather than originally planned 1000cc.
 

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It was my understanding that the drive motor IS 100kW, it's the generator that puts out 53kW peak. That combined with the 30% reserve of the attery could provide the other 47kW to still have the same or similar output as pure battery power, so only the longest and steepest of hills would one run the battery dry and rely on only ICE power. Am I wrong in this?
 

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The spec sheet in the Chevy-Volt site is rather vague in this area. It says max electrical power is 130 – 140KW, which I think the battery pack and the generator are capable of delivering combined. But, for an electric motor rated at 45KW continuous this three-fold increase in power must be for a very short burst. Certainly this much of power increase cannot be sustained to go up a hill. The tremendous amount of current can easily fry the motor windings. So, you need a motor rated at 75KW or so continuous if you want to keep up with others.
 

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The non-turbocharged version of the 1.0 L 3cyl. is rated at 44KW/60 HP
The non-turbocharged version of the 1.4 L 4cyl. is rated at 66 KW/90 HP.
Don't know how much the turbo will boost its HP, if any of you guys know, post it.
_=-
 

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The spec sheet in the Chevy-Volt site is rather vague in this area. It says max electrical power is 130 – 140KW, which I think the battery pack and the generator are capable of delivering combined. But, for an electric motor rated at 45KW continuous this three-fold increase in power must be for a very short burst. Certainly this much of power increase cannot be sustained to go up a hill. The tremendous amount of current can easily fry the motor windings. So, you need a motor rated at 75KW or so continuous if you want to keep up with others.
Good point. Perhaps they designed it with generally flat highway driving in mind for the high end of continuous operation.
 

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I hope you agree that we need at least 100HP or 75KW of power to move a 3500Lb car uphill at a “decent” speed with some reserve. GM’s smallest car Aveo, which weighs 2531Lbs, is rated at 103HP or 77KW, for example.
I guess the question I have is why you need to have a car weigh 3500lbs in this day and age in the first place. Or 2500lbs for that matter.

My Minis weigh about 1600lbs wet and with a pudgy driver. The one with the 1.0L motor generates probably no more than 35HP. It is adequate for everything but sustained uphill driving (though acceleration can be a little underwhelming). The 1.3L motor generates about 49HP. The peformance of this car is comperable in every way with one twice it's size and weight, and with near double the engine capacity and available HP.
 

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mwalsh, now we are talking about a new category of automobiles to which people in North America have not paid much attention so far. When Sir Alec Issigonis designed the Mini it did not get much attention in North America. At that time we thought the bigger and more powerful a car, the better. Today, we can reduce gas consumption by 20 to 30 percent easily by switching to Mini type automobiles. We even do not have to talk about hybrids. Last week I rented a Yaris and drove about 300 mostly highway miles. As I filled the car up to return it I realized I used only 6.9 gallons of gas, or about 43mpg. Better yet, if many of us drive the “kei car” type of automobiles, which are very popular in Japan, we can reduce gas consumption even more. They come with a 0.66 litre engine producing about 60HP and all the modern amenities and safety features. They are quite acceptable for city commuting.

The beauty of the Volt is that it is designed (originally at least) for short-distance commuting consuming no gas most of the time. The ICE is for just-in-case purpose and it must be small and light. If you try to make the Volt a universal purpose automobile, you are defeating the original design. For the universal use the parallel design (as opposed to serial) is better although mechanically it is more complicated.
 

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Lutz had stated that there were engine smoothness problems with the 1.0 Turbo. The goal of the Volt's ICE is max HP at min RPM, one of the reasons that the 1.0 was turbocharged. The hope was that the ICE would run at or around 2K rpm. I don't have any figures but it's conceivable that the 1.4 and 1.0T have roughly the same HP @2K RPM and the 4 is probably smoother. It could also be that with 1 more cylinder the ICE may run at 16-18K rpm with the same power as the 1.0T @2K resulting in fuel savings. No specs here, just guessing.
 

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Sorry, the size of ICE does make a big difference. You cannot get something out of nothing. For a generator to produce a required amount of electrical power the ICE that drives it should have slightly more mechanical power because of the loss incurred in the process of energy conversion.
All you need is a big enough ICE to turn the generator at full output. Anything else is wasted. That was my point.

I hope you agree that we need at least 100HP or 75KW of power to move a 3500Lb car uphill at a “decent” speed with some reserve. GM’s smallest car Aveo, which weighs 2531Lbs, is rated at 103HP or 77KW, for example.
I agree to nothing. I am not a mechanical engineer. I am an electrical engineer. Since it does not matter in this discussion, so be it. You are not going to get 77kW from the ICE. All you are going to get is the 53kW peek from the generator that the ICE is turning unless you are now saying they intend to increase the size of the generator above 53kW.
Now, let’s take a look at the Volt specs. Its electrical power is rated at 45KW constant and 53KW peak. This should be OK for driving on flat city streets to commute, but certainly is not enough to keep up with 150HP “family” cars running side-by-side up the Tejon pass on the I-5. The only way to improve performance of the Volt in this case is to increase the power rating of the driving motor, to as much as 100KW. I do not know whether this is practical or not. However, the fact GM is contemplating increasing the output power of the ICE means it intends to increase the output power of the driving motor. In the serial hybrid design the output of the ICE should be somewhat higher than the output of the driving motor if you want to maintain the “decent” performance, since it has to power the generator which supplies current to both driving motor and battery pack (when the battery pack is depleted). Suppose the output power of driving motor is 75KW, you need as much as 80KW or 107HP generated at the ICE, thence the requirement for 1400cc displacement rather than originally planned 1000cc.
The traction motor is 120kW. You will never get the 75 or 100 kW you think you need out of the 53kW generator. Anything over 53 kW will come out of the battery stack. That is why the ICE comes on at 30% SOC (State Of Charge). That way there is still enough in the battery stack for climbing hills and passing cars. You only need 20kW to maintain 60MPH on flat ground if the Volt has the same CD as the Rav4EV. If the hill is long enough and the grade is steap enough, you will have a problem maintaining 80MPH going up hill. I. E. Don't start up Pike's Peek with a dead battery. It will never be as bad as a loaded 18-wheeler at climbing hills though.
 

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Grizzly,
OK, let's suppose we want a 100HP (75kW continuous) electric motor to make the Volt practical for freeway uphill driving (although I do not think this is a good idea). In this case you need an ICE of slightly more than 100HP of output power, which you can produce with either 1.4NA I-4 or 1.0T I-3. Which is better for the application? I would go with the 1.4NA even though it is heavier and its mechanical friction is higher than that of the 1.0T. As Lutz stated the I-4 should be smoother. Also, you do not have to worry about turbo-related problems such as heat and frequent oil changes. The flywheel effect of the generator rotor should be able to smooth out the remaining roughness of the 4-banger. Also, by turning the heavy generator into the starter motor you should be able to absorb the start up shudder of the ICE.

But, all in all, why bother with more powerful (and smoother) yet heavier ICE? I would prefer a lightweight Volt with electric only mode as its main purpose even with somewhat higher vibration when the 1.0 I-3 ICE (doesn’t have to be turbocharged if the power requirement is 60HP or so) is running. When the SOC goes down to 30% the vibration will remind you that you are in the limp mode, which should not happen so often for a commuter.
 
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