GM Volt 1.4 ICE Range Extender

[cfg83]

Allch Chcar -

Originally Posted by Allch Chcar

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.

...

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

[Allch Chcar]

yes...turbo reduces BSFC.

[cfg83]

Allch Chcar -

Originally Posted by Allch Chcar

yes...turbo reduces BSFC.

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

Since the four cylinder engine is also longer, GM has had to reconfigure the packaging somewhat to make it fit, which as per Nitz is "turning out nice."

CarloSW2

[RobertSmalls]

Originally Posted by Allch Chcar

yes...turbo reduces BSFC.

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.

[NeilBlanchard]

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?

[cfg83]

NeilBlanchard -

Originally Posted by NeilBlanchard

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?

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

OPEL Corsa 3 Doors 1.0 12V 2006 - Present - autoevolution

Cylinders: L3
Displacement: 998 cm3
Power [KW(hp)/RPM]: 44(60)/5600
Torque: 65/3800 lb-ft/RPM (88/3800 Nm/RPM)
Fuel System: Multipoint Injection
Fuel: Petrol
CO² Emissions: 134 g/km

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

[cfg83]

Hello -

Here's more info on the 1.4 :

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

GM has yet to publicly demonstrate the car operating in this charge-sustaining mode, but most accounts indicate it is unnoticeable.

In spite of many months of rampant speculation here, GM’s lead Volt engineer Andrew Farah has finally disclosed some details about the engine’s operation. He said the generator would “operate from 1200 to 4000 RPMs and from a 30% to 100% load.”

Further explanation comes from Volt Powertrain Engineer Alex Cattelan:

“We don’t keep it at a fixed RPM, we have a window of operation that is optimized. We have been able to optimize the engine for a window of efficiency but it is still best to change your power and torque levels within that window as the customer torque request varies.”

“We don’t want to always be operating at one state because really you may be putting too much energy into the battery or drawing too much energy out of the battery. It is still good to vary that engine power and torque. Not to follow exactly what the accelerator pedal does, but to optimize efficiency.”

Finally Volt vehicle line director Tony Posawatz explains it this way:

“In charge sustaining or range extender mode, the Volt will not follow the throttle position. The challenge is to select the right operating points (RPMs) that are 1.) efficient, 2.) pleasing to the driver, and 3.) meet regulatory requirements.”

CarloSW2

[NeilBlanchard]

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.

[Allch Chcar]

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.

[dcb]

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