Comments on: Is a Mazda Rotary-Fed Volt Fighter On Its Way?

By: Van

Van — Mon, 03 Sep 2012 17:56:06 +0000

I think the little fish are waiting for the big fish to develop the next generation battery, i.e 400 Wh/kg at a cost of $125/kwh. Then as the song goes they will swim and swim all over the dam.

By: Al Bunzel

Al Bunzel — Mon, 03 Sep 2012 17:42:20 +0000

Why is Mazda waiting to produce their EV with range extender? If they really wanted to have a range extender, couldn't they use an existing engine they already produce?

In my opinion, it is just another stall tactic so that they can say they are working on an EV, but it is still under development because the gas motor is still be "developed".

By: John D.

John D. — Sun, 02 Sep 2012 14:11:04 +0000

The most efficient Diesel engines are actually found in locomotives. We think of them as big heavy beasts, but what is going on is really cool. They are two stroke supercharged diesels that operate at one specific RPM. The intake compressor keeps the manifold at a significant pressure (air only.) Each cylinder only has exhaust valves. At the bottom of the “Power” stroke, a slot at the bottom of the cylinder is uncovered allowing the pressurized air to enter. At the same time, the exhaust valves open. This purges the cylinder while burning off any unburnt fuel elements. (No catalytic needed!) The valves close and the air is compressed. Near TDC, the fuel is injected and the power stroke begins again. Half the cycles = half the friction. Power is controlled by the quantity of fuel injected. This engine turns a generator, which runs an inverter/chopper that drives the traction motors on the wheels. There are technical issues regarding downsizing the design, and locomotive engines have a horrible start-up until manifold pressure is attained. Still, with a little work, I think it is something we may someday see adopted.

By: Van

Van — Sun, 02 Sep 2012 14:04:18 +0000

I had the pleasure of driving a rotary engine sports car, smooth as silk.
But as John D alluded to, it used oil.

I think thermal efficiency is a good indicator for choosing which engine to buy, but without a reliable information source, we get numbers for various engines from 15% to over 50%.

As a rule of thumb, most of us accept that Diesel engines are more efficient than gasoline engines, so expect 28% to 38% thermal efficiency for gas and 38% to 43% for diesel car engines. For example a Jetta TDI diesel gets 41% versus the Prius at 37%.

By: No more carcinogenic diesels

No more carcinogenic diesels — Sun, 02 Sep 2012 12:45:04 +0000

Jim Larsen: Only in your dreams. Diesel engines found in the passenger cars never get over 50% thermal efficiency, more like 30-35% at best.
However 50% can be achieved in big ship engines but those have nothing to do with car engines.
Atkinson cycle engines in hybrid powertrain have given the best efficiency so far, diesels are behind them and much more polluting.

http://www.youtube.com/watch?v=ySR0flj6QnQ

By: Jim Larsen

Jim Larsen — Sun, 02 Sep 2012 07:27:12 +0000

Diesels already get over 50%. There isn’t much value in an Atkinson engine when compared to that.

By: Jim Larsen

Jim Larsen — Sun, 02 Sep 2012 07:26:19 +0000

Diesels already get over 50%. There isn’t much value in an Atkinson engine when compared to that.

By: John D.

John D. — Sat, 01 Sep 2012 17:39:13 +0000

I think they (Prius / Atkinson) are at 34% now, so adding 6% is not science fiction. What a change from the expected norm of 15% (Otto) a few years back! Still, I like the idea that every design concept (just about) is on the table! May the best one win!

By: Kurth

Kurth — Sat, 01 Sep 2012 05:06:05 +0000

High thermal efficiency is what I am waiting for, Prius is going to break 40% soon with their atkinson cycle engine, and is mated with a very low CD. Mazda is my favorite car company, so I am looking forward to see what they will come up with.

By: tgordi

tgordi — Sat, 01 Sep 2012 03:14:29 +0000

The best engine sound I know of is that of our Nissan Leaf. When you push the gas pedal, the car jumps with a Batmobile sound. And I love it!