Electric Drive: Who uses it?

[a64pilot]

Then you have this neat concept, now we can squeeze more power out of low octane fuel
https://www.roadandtrack.com/new-car...works-and-why/

[a64pilot]

Or how about a Diesel that runs on gasoline?
Diesel fuel has some issues in cleaning it up, so why not run the Diesel cycle with gasoline fuel?
https://www.roadandtrack.com/new-car...s-clean-as-ev/

The 70’s were not the days of the motor heads like we used to think, the 21st Century is, with modern electronic controls, things that before were possible only in theory are finding their way into aitomobiles

[Dockhead]

Originally Posted by a64pilot

Respectfully pumping losses have nothing to do with the Atkinson cycle, entirely separate issue.
The modern pseudo Atkinson cycle engines have more pumping loss than a regular Otto cycle engine, the reason is that they simulate the Atkinson cycle by valve timing, they leave a valve open until well up on the compression stroke, before they close it, and of course pumping all that air through an open valve is pumping loss.

However the Prius and other such cars I’m sure have essentially zero pumping loss as the computer operates them at usually full throttle, but drawing them down in RPM so that the engine at full throttle produces just the amount of power required, and will vary RPM and not throttle to reduce or increase power output.

Actually if you look, you will find that the modern Diesel is dropping in compression rather markedly, and the modern gas motor increasing.
They will soon meet.
Rather odd place for this article, but read this
https://www.economist.com/babbage/20...ine-born-again

It's likely that I am misinformed, and that you understand it better, but what I understand is that Atkinson cycle engines of the Prius type using variable intake valve timing do modulate power output largely using valve timing rather than the throttle plate. THAT certainly reduces pumping losses, which is the number one difference in efficiency between diesels and ottos. Pumping air through an open valve is no different from what diesels do, and costs little energy -- real pumping losses come from forcing air past a throttle plate which is partially closed closed to create a partial vacuum to reduce the charge to modulate power.

But if I heard something wrong about this, please correct me.

[Dockhead]

Originally Posted by a64pilot

Then you have this neat concept, now we can squeeze more power out of low octane fuel
https://www.roadandtrack.com/new-car...works-and-why/

That's cool, but how efficient will that be at 8:1?

What's brilliant about the Atkinson cycle -- even the quasi-Atkinson cycle Prius -- is that it de-couples the compression ratio from expansion ratio so that you can let the gasses expand.

But a highly pressurized turbo diesel gets a similar effect out of the turbine -- the still-energized, still-expanding gasses drive the turbine. I'm not sure it's even theoretically possible for a spark-ignited Atkinson engine to match an advanced turbodiesel. In which case this engine may be really useful only for the American market, where there are regulatory barriers against diesels.

I don't know if you've ever driven one of those brutal sequentially turbocharged BMW's -- it is a remarkable experience. It's just the opposite of my old 2.2 liter Porsche 911S's, which were like Volkswagens until they got on the cam (which happened at exactly 5200 RPM), and then watch out! I loved those cars, which gave infinite pleasure driving hard, but the new BMWs, I would say, give maybe even the same kind of pleasure, just in a completely different way, with sheer brutality, seemingly infinite torque practically from idle, and lots of gears. They've got them producing well over 100bhp/liter -- freaking crazy.


I just love diesels; I have mostly lost interest in otto engines.

[a64pilot]

Originally Posted by Dockhead

That's cool, but how efficient will that be at 8:1?
.

It’s actually not all that inefficient, but that not the idea of lowering the compression ratio.
Normally aspirated engines are more efficient at higher compression ratios, however to prevent detonation this requires high octane fuel.
Then you take a high compression engine and boost it, and you have to have stupid high octane fuel.
So ideally you have an engine that runs around at high compression for efficiency when at low throttle settings, but lowers its compression so the turbo can really add some real boost and get a significant boost in power, you get your cake, and you get to eat it too, an efficient engine, that can make significant power.

[a64pilot]

The Prius can vary valve timing for power, I suspect this is what happens when it comes out of Eco mode and into Power mode on the instrument display, it come out of the Atkinson cycle somewhat and into the Otto, but if driven as it should be, that is always in Eco mode, it varies it’s RPM to increase power, not the throttle plate, it within certain limits of course will leave the throttle plate fully opened.
Thereby doing something that was always beaten into my head as being bad on an engine, lugging it. It’s real common to be going down the road at significant speed and see 900 RPM or even slightly less.
I used to tap into the OBDII port on my Prius trying to determine what was going on, and it was interesting, RPM was all over the place, and there were many times when the engine would be turning, but not consuming any fuel, and other unusual things.
In my opinion the Prius is so efficient not so much due to it being a hybrid, but to a great extent to how it’s internal combustion engine is managed.
Prius development has pretty much come to a standstill, cause of market forces, they are increasing in size and weight, but being able to maintain similar efficiency, it would be very easy to make one at least 10%, but likely up to 25% more efficient, but that’s not what the market wants.

When comparing efficiency of the Prius to other cars, look at the size and weight of the Prius, it’s not a small car actually, it can easily and comfortably carry four adults.

First sequential turbo I drove I think was a Masaratti Bi turbo decades ago, at least I think it was sequential turbo.
But you can make a turbo far more flexible also, you can have variable in,etc guide canes and make it so it acts like a small turbo, and a large one also. The variable inlet guide vane turbos are common on Diesel pickups I think.

[Dockhead]

Originally Posted by a64pilot

The Prius can vary valve timing for power, I suspect this is what happens when it comes out of Eco mode and into Power mode on the instrument display, it come out of the Atkinson cycle somewhat and into the Otto, but if driven as it should be, that is always in Eco mode, it varies it’s RPM to increase power, not the throttle plate, it within certain limits of course will leave the throttle plate fully opened.. .. .

Well, then it's overcoming Otto cycle pumping losses .

If power is not modulated by throttle plate, then it must be by intake valve timing, non? Modulation of power is the big problem with Otto cycle engines, and if the Prius is able to modulate power output while keeping the throttle plate open, then it's made a huge leap towards diesel efficiency

You say "by RPM", but that can't be right -- what changes RPM? I'm guessing intake valve timing, if it's not the throttle plate -- there's hardly any other way to do it with a spark ignition engine.

[a64pilot]

Originally Posted by Dockhead

Well, then it's overcoming Otto cycle pumping losses .

If power is not modulated by throttle plate, then it must be by intake valve timing, non? Modulation of power is the big problem with Otto cycle engines, and if the Prius is able to modulate power output while keeping the throttle plate open, then it's made a huge leap towards diesel efficiency

You say "by RPM", but that can't be right -- what changes RPM? I'm guessing intake valve timing, if it's not the throttle plate -- there's hardly any other way to do it with a spark ignition engine.

There is no transmission, it’s a “power spilt device” is actually a planetary gear system that can vary gear ratios over a very wide range.
It’s an ECVT if you will, the Prius will simply increase the gear ratio until the RPM of the engine is drawn down low enough so that at full throttle it wont accelerate. It reduces pumping losses to nil as there are none, but also reduces mechanical friction to its lowest possible limits as the engine is running at its lowest possible RPM. It does that by varying the other planetary inputs in this case MG2 which is the motor generator attached to the wheels. There are limits of course to the ratios that can be achieved, for this reason 42 mph is the max speed the car can go on pure electric mode without RPM input from MG1 or the electric motor generator mounted on the engine flywheel, or the ICE of course so to prevent overspeeding MG2, the engine has to spin at speeds above 42 mph, but it can do so in pure electric mode, at which case the throttle valve is completely closed to lessen pumping losses, or it can do so with throttle valve completely open to increase pumping loss to max such as when going down hill, it can also increase the engine RPM significantly to control vehicle speed when going down hill, essentially using the engine as a big air compressor to waste energy as well as regenerative braking of course. If driven properly, a Prius will never need brake pads, they are only needed below 5MPH where regen becomes inop. But of course are always there for emergencies.
There is no master cylinder on a Prius, can’t be it you would use mechanical brakes, it’s a rather complex hydraulic system with an accumulator and a “stroke simulator” to match the feel of a master cylinder. When you open the door on a Prius, you hear a buzz and a relay click, that was the brake accumulator pump building pressure in the accumulator.

The planetary gears in the PSD are constantly meshed, there is no neutral or reverse possible, you can only vary rpm of the different planet gears to change output ratios drastically, or allow one or more to run backwards to simulate if you will a neutral so the engine can run without moving the car.
Reverse is MG2 being run in reverse direction, reverse is a pure electric only mode. The first Prius models couldn’t pull a steep hill in reverse, they didn’t have the torque to do so. People in San Francisco got stuck sometimes.


I know this is drift, but it goes to try to explain why a Hybrid car is so sophisticated a system, and why we can’t just cob together electric motors, car batteries and off the shelf generators and get anything like a Hybrid automobile.
When you really drill into the things, the more brilliant the Engineering you find.
A large problem with a Hybrid is keeping the engine warm cause it’s so rarely run, Gen II Prius upon engine shutdown, the coolant pump would pump all the coolant out of the engine and place it into a large thermos bottle, where it could stay hot for two days, Gen III Prius runs the coolant through the catalytic converter to absorb the considerable heat from the Cat.
There are no belt driven engine accessories, no belt actually, in fact there is no alternator or starter, water pump and air conditioning are electrically driven as well as brake pressure

[james247]

Originally Posted by storx

I was curious how many folks on here use electric drive on their powered boats?



There is a guy up at my work who i recently came across with who owns a 41ft defever trawler. He claims he got the boat for nearly nothing because one of the seals on the driveline failed flooding the engine room before they got it out of the water. The motors were needing to be rebuilt he claimed, so he pulled the motors out and replaced them with electric motors from a kit he bought online. He said he uses tesla model s batteries to power the motors.



So my question is how has these worked out for folks so far, ive always been a big electric car fan, i currently daily drive an electric car.



He said his boat has a 12.5kw diesel generator, when he wants to cruise long distance he will power the generator up and run the electric motors at half speed and the output on the generator will provide plenty of power to the circuit to not drain the batteries down while cruising around, he stated he is planning on upgrading the generator to a larger generator in the future, or possibly add an additional 2nd generator onboard for cruising at full speed, but for now he is plenty happy with the speed he can cruise at.



He said when he needs to run full speed, he can crank them up and get about 45-50 miles out of the battery bank before it drops to low to maintain full speed. stated he plans to add additional tesla batteries to the setup when he can source them for a decent price, stated the price of them has nearly doubled since purchasing the ones currently powering his boat.

The Chinese are the real innovators of battery power. Do some research and save some money. If you design the batteries into a sailing yacht the whole ballast moment of heel factor changes very positively. By keeping the weight more central the pitching hobby horsing factor also decreases. Charging systems are also a major factor. Getting 12.5 Kva from a generator into a battery and into an electric motor is half the trick. Semi's and buses are now going electric. It's the future.

[james247]

Originally Posted by john61ct

Some people just like spending their time and money on Science Projects.

More power to them.

As renewables-produced electricity gets more practical in a mobile context, he'll be ready to start (slightly) reducing his diesel burned per mile traveled.

Or perhaps the plan is hopping from marina to marina recharging overnight?

That argument is about the evolution of mankind. Take that argue met back and we would still be living in caves. Someone has to be the innovator

[james247]

Originally Posted by skipmac

Not millions but certainly tens of thousands.

Don't fear some government will ban diesel and petrol engines sooner or later then things will change. Britain just banned singlet bags in supermarkets. Just accept it will happen. The innovations will come sooner than later

[a64pilot]

When internal combustion engines are banned, where are you going to get the power?
Do you have any idea at all how much increase in electrical power generation would be required?

[skipmac]

Originally Posted by james247

Don't fear some government will ban diesel and petrol engines sooner or later then things will change. Britain just banned singlet bags in supermarkets. Just accept it will happen. The innovations will come sooner than later

Not too likely. What will they replace them with?

Whatever country did that their economy would collapse and the country descend into chaos.

Not to mention there's over a billions cars and trucks on the road worldwide. Would be pretty hard to make those go away.

[Wayfarer1008]

LOL I know this person is trying to justify what they are doing but its going to be a disaster and forget about ever selling it. One of the problems that electrical bow thrusters suffer from that will affect this repower is that while the motor is being pushed hard it creates a lot of heat to the point they will shut down. This maybe a real issue with this setup that will has to be addressed if not expect to loose power at the one moment you need maximum thrust. By the way as I said in a previous blurb If the boat is designed from the ground to be electric you are well ahead of the game. Duffy's are and probably the best example of an electric boat and have a hull design to take advantage of the power to hull setup Attached is an advertisement for a Duffy 30. they were the biggest boat Duffy built and would be along the lines you would want to propel your boat with an electrical power plant. https://orangecounty.craigslist.org/boa/6539630417.html

[john61ct]

Originally Posted by james247

That argument is about the evolution of mankind. Take that argue met back and we would still be living in caves. Someone has to be the innovator

And I very positively supported that idea.

As long as those pouring money and effort into such projects **are aware** they are experimenting For Science.

It's those that are looking for here and now practicality that need warnings not to heed the overly unrealistic optimists.