GM Volt 1.4 ICE Range Extender
 

Hello -

dcb's series-hybrid thread led me to find this :

GM Explains Why the 1.4 L ICE Range Extender was Chosen For the Volt - July 26th, 2008
CarloSW2

Ok, but why not use a diesel?

Speculation, I suspect NO{x} emissions and weight. A simple, three-way, catalytic converter can handle gasoline emissions. Also, the lower stresses of the gas engine should give a higher power to weight ratio compared to an equivalent power diesel engine. For example, chain saws seldom use diesel cycles, with one exception, "Comet" from the 1950s.

Bob Wilson

Because they want it to work and they wanted to make it themselves.

Don

I do have issue with disguising the ICE operation. I think it should be a LOT more obvious that you are going to start burning fuel, or are burning fuel. Perhaps a personal preference, perhaps pandering to soft consumers, but If I bought something as presumptuously named as "volt" and discovered I had been running tons of fuel through it then I would be a little pissed, as someone who is trying to reduce petrol dependencies.

I have to wonder what the range extender is doing to cost/red tape/epa concerns/delays to market. And I have to wonder if GM wants to delay its release.

No kidding, a turbo on a range extender was a really dumb idea. They should have just use the 1.0liter then it would have been cheaper, lighter, and more efficient. But they decided to use the Volt as a Range Extender instead of a battery charger so once the battery hits it's Depth of Discharge boom it's ICE powered till you plug in the battery. Thankfully the inefficiency of going through the generator and the drive motor is at least respectable or it'd get worse efficiency than an ICE powered Volt.

There is other variables too. The durability of a 1.0liter Turbo could be less than the 1.4liter if it was ran with the turbo running even half of the time. Turboes are not a good choice on Electric Vehicles anyway.

Why use a diesel?
It's heavier and more expensive. That alone disqualified it before we had a chance to even consider. I'd love to discuss it more. Now with DI getting more expensive I don't doubt the price is becoming comparable to Diesels. But Diesel is necessary for Commercial vehicles so any more competition with business is bad in my book.

And I agree with you dcb. But when they build a mass market car that annoying ICE needs to be silent for them consumers. I don't mind a noisy car even if it is a bit annoying but the silent ones are the dangerous ones. The Prius received flak for being quiet at <35mph but many cars could run you over before you heard them coming at much faster speeds. Double standards. I grew up being extremely cautious about roads and when I did start spending a lot of time around traffic I would still be caught off guard by vehicles that I couldn't see or hear until they were too close for comfort.

This is a side issue:It turns out noisy SUVs and pickup trucks are the primary pedestrian killers. As for the Prius, the actual fatality rate is much less than the USA fleet:

Prius Fatalities 2001-2007

I would point out GM has not put noise makers on their existing hybrids ...

Bob Wilson

I knew that discussion would ring a bell with you Bob :)

...does that mean EV's are like the prodigal kids, who should be "...seen, but not heard"?

Tuesday morning, C-SPAN, Washington Journal, enjoy:

* Jim Campbell, General Motors Company, Chevrolet General Manager
* Susan Cischke, Ford Motor Company, Group Vice President
* Jim O'Donnell, BMW of North America, Chairman & CEO

Bob Wilson

Allch Chcar -

I don't understand your statement. They aren't using the turbo. They are using the non-turbo 1.4. Do you mean it was a dumb idea to even *consider* the 1.0 turbo? It also appears that the 1.0 is a 3 cylinder.

CarloSW2

yes...turbo reduces BSFC.

Allch Chcar -

Ok, that makes sense. I have a hunch that the 1.0 3-banger was in the mix because of engine bay real-estate :

CarloSW2

How? It's an exhaust waste energy recovery device. Ordinarily, the reduced compression ratio could harm BSFC down low to allow boost up high, but if the Volt runs at a near-constant load, they should be able to tune it for better efficiency with a turbo than without.

I believe their decision came down to cost and NVH, but primarily NVH. That's unfortunate.

Hi,

I think it was essentially "parts bins engineering" -- they already make a 1.4L 4-cylinder. They would have had to design the smaller engine from scratch.

Here's a purpose made "range extender" that is damn big -- 35kW driven by a 1.2L 3-cylinder: Green Car Congress: Lotus to Introduce Range Extender Engine. That should be able to run two or three Volts?

NeilBlanchard -

I think the 1.0 (sans turbo) was also from the Opel parts bin :

OPEL Corsa 3 Doors 1.0 12V 2006 - Present - autoevolution
Here's another factor in what I am thinking. If I can tool a factory for the same engine displacement and make a Chevy Volt 1.4 without a turbo and a Chevy Cruze 1.4 with a turbo, that's a win-win for my capital investment.

CarloSW2

Hello -

Here's more info on the 1.4 :

Chevy Volt Engine Generator Operates Between 1200 and 4000 RPM - October 2009
CarloSW2

The other reason I have heard for why they did the Volt this way, is to force you to always plug it in when you can. It makes just enough as it goes along, and then you will plug it in to get a more efficient energy source.

RobertSmalls,
They said they didn't get a better BSFC. A turbo reduces BSFC unless you increase the octane required aka "premium" gasoline. I doubt they'd lie about their findings and while that's not impossible there is overwhelming evidence for worse BSFC with a turbo vs N/A even when comparing a smaller turbo engine with a bigger Natural Aspirated engine.

BSFC decreases with larger engine sizes and increases with faster engine speed. In a generator like the Ranger extender that makes the case for a bigger engine vs a small turboed engine.

I don't think 50mpg in hybrid mode is terribly spectacular. And as far as I know, that was on the hiway.

Good idea.

Engineer the car to drive slower once the battery pack gets low. You would encourage people to charge up more often at the same time reduce gas consumption by FORCING responsible driving habits.

I guess this means that the chances of a cel-phone wearing, redneck Volt driver cutting you off in a highway construction zone is going to be rather slim. :turtle: Ha!

...should get really interesting just about the moment you start up and onto the freeway "on" ramp!

No, in this case you would be looking to get on the freeway using a "down" ramp. :turtle:

Hello -

I thought this was interesting :

2011 Chevrolet Volt - Chevy Electric Midsize Sedan - Automobile Magazine
Does the Prius or Insight try to keep the batteries warm during recharging?

CarloSW2

The 2000 Insight simply refuses to charge its batteries very hard when they're very cold. Regen starts to fall off when it's below freezing out, and at 10°F, I have almost none. Assist is also reduced with temperature, and at -20°F the 12V starter gets used. The Volt has lithium ion batteries instead of my NiMH, but I imagine they'll be all but useless in frigid weather.

What I don't get is why they need a 1.4ltr on a series hybrid.

The whole purpose of a series hybrid is to use a taylored high efficiency SINGLE SPEED motor to drive your genny. Like the 60mpg military turbine generator powered humvy we all got our panties in a bind about several years ago. You can easily gain 25% by setting a motor up to be tuned for one speed.

Also to me that would mean a 1ltr NON TURBO should be sufficient to maintain 65mph. (And I doubt GM would have any trouble finding a 1ltr engine, it seems many here still drive one with a GMish badge on it.)

Your goal of coarse would be to fire up the motor to the ideal operating speed REGARDLESS of vehicle speed once the generator charges the batteries a predetermined ideal amount (depends on how long the motor takes to get "ideal") Then shut down and cycle on and off as needed while the vehicle motors along. Sort of like pulse and glide, allows the motor to only operate in its most efficient band.

That is one way to set up a serial hybrid, but Chevy has not done it that way -- they vary the ICE RPM's to adjust to the required power, and they do not charge the battery with the ICE. The reason they do this (they say) is to force you to recharge it when you get to a plug.

I'm not sure this is the right choice, overall -- but I'm sure it depends on how much you drive it each day. I think that since they had to do parts bin engineering, and used the 1.4L to begin with, they may have made the best choice for this design...

NeilBlanchard -

I agree. We know a 1.0 turbo was in the running. I don't have the URL, but I *thought* a non-turbo 1.0 was also considered (but maybe the 1.0 was always a turbo).

At then end of the day they went with the 1.4. The latest Prius is up to a 1.8 @ 3000 lbs curb weight. A Volt with a 1.4 @ 3500 lbs curb weight is "reasonable" to me.

CarloSW2

Sounds to me that they were actually just being lazy as that requires less R&D to determine optimal operation and discharge/recharge intervals.

Any motor, even their stock 1.4l has an ideal power output, keeping the motor there as much as possible is always better than the nearly 50% variation in efficiency when you run the gamut from idle to WOT.

This brings up a point, since the motor is decoupled seems that an ECU reprogram or a manual control of the ice could allow future owners to improve the ICE mode operation of their volt.

If it works and is affordable to us, then great!

Everybody thinks they know better than GM's engineers.

NeilBlanchard -

You made me look. The Toyota Prius engine, while optimized for the Atkinson cycle, is also shared with other cars :

Toyota ZR engine - Wikipedia, the free encyclopedia
Toyota ZR engine - Wikipedia, the free encyclopedia
CarloSW2

For strictly fuel economy yes we probably do they don't design that way. And certainly would not want the driver to have to think a little about their trip type and length to optimize FE.

My diesel suburban and the buick are good examples of where I did know better, at least for FE than GM.

GM however wasn't appealing to what I was specifically looking to get out of those vehicles, they were appealing to a different market.

Also remember the engineer does not always have 100% input on what the vehicle does, they can give suggestion but inevitably put in what they are told to.

Cheers
Ryan

Automakers always leave some fuel economy on the table. Even in their green vehicles.