GM Volt Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
250 Posts
Discussion Starter #1 (Edited)
I bit the bullet and downloaded the SAE paper on the Gen 2 Volt engine. Best BSFC island is 230 g/kWh. With the given fuel spec, that comes out to ~36.5% peak efficiency.

For reference:
Gen 1 Volt engine peaked at 240 g/kWh (~35%)
2010 Prius peaked at 220 g/kWh (~38%)
2016 Prius and Hyundai Ionic apparently hit 40% thermal efficiency, which is roughly 205 g/kWh
Honda EarthDreams peaks at 214 g/kWh (39%)
TDI engines peak out around 196-197 g/kWh for comparison (42.5%)

Having read the whitepaper, I think some sacrifices of efficiency were made to get higher specific output (on 87 too), as they pushed the new engine family as far as possible for displacement. If you notice, the Prius engine makes less power with a higher displacement engine, affording them the ability to make some more efficient choices. That's the benefit of having started with a larger gasoline engine.

I thought everyone would be interested.
 

·
Registered
Joined
·
354 Posts
Thanks,

I was just thinking about this subject when I was doing an 800 mile round trip in the Volt last weekend. Running those consumption figures and roughly doing a ratio between cars of similar mass it seems to ring true with my observations on the street. It is obvious diesel has more energy content than gasoline from comparing the mileage from my old VW golf tdi to the Volt running on gas. I have been doing this same route for 20 years to visit family and it has many sections of either mountains or 75 mph speed limits. Bottom line is that the diesel does 3mpg better. The Volt did great at elevation because the electric portion had plenty of poke to make up for the ice power loss.

The real epiphany for me was realizing how much more thermally efficient the electric motors are. The battery in the gen 2 has the equivalent energy of only 1/2 gallon of gasoline, but can do 50+ miles (106mpge). The statement that a gas engine wastes most of its energy through the radiator was just a statement until I had time to think about how the volt works. Also I work in industrial inverter industry and with locomotive/mining truck drives and it was quite striking how much less diesel fuel is burned in an induction drive vs a mechanical mining truck in the same weight class.
 
1 - 2 of 2 Posts
Top