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World's Only Diesel-Electric Honda Insight
Jake Staub writes "Just replaced the gasoline engine in a Honda Insight with a Diesel engine. On a 3,000 mile cross-country shakedown journey the car averaged 92mpg over 1,800 miles. Around a very hilly town in Northwest Washington, the car is averaging 78mpg. These mileage averages are without the electric side of the vehicle fully functional. With a bit more tinkering on the electric side and through a slight gearing change through tire size, it is anticipated that the car will likely average 100mpg. The build for the car has been documented on the web site and is as close to open source as my time allows. The car was built by two guys in a garage in Southern Maryland. If we can do it I don't see any reason why major auto manufacturers can't do it since we used their parts."
Since the site has been /.'ed and I can't RTFA, I have to ask... Is this really a Diesel Electric engine (as in locomotives) where the diesel engine is used solely to create electricity and is not connected to the drive train? Or is this actually a Diesel Hybrid?
The main reason gasoline hybrids get better mileage than direct-coupled engines is that the gasoline engine is not forced to operate at inefficient points on its' BSFC map (near closed throttle). The engine only runs when needed, and then it runs near its' BEP (Best efficiency point), or occasionally at maximum power which also has decent efficiency. It is not forced to idle and off-idle conditions where the pumping losses are horrible and efficiency s#x (5x fuel for same marginal power).
Diesel engines have entirely different BSFC maps, and do not suffer the same pumping losses (vacuum across throttle plate). Their drop off at idle is _much_ lower than for gasoline engines, so they're great in city-wide European traffic jams. Diesel fuel also is ~15% denser (more heat per gallon) and the higher compression ratio is about 5% more theoretically efficient.
But a diesel hybrid does not have much to gain by hybridization. The BSFC map is much flatter, and the engine restarting power & wear is considerably higher.
I'm quite certain the Volt is in fact in production at this point, and yes I'm speaking of series hybrid drives but that doesn't invalidate my point at all.
My point was simply about using hybrid drives at all, and the choice to use parallel hybrid drives for gasoline engines stems precisely from inefficiencies.
As another person replied, a series hybrid will never be more efficient than a straight engine, but that's ignoring the charging of the batteries through third party options like regenerative braking, solar collection and wall sockets.
- Michael T. Babcock (Yes, I blog)
For various reasons the industry in the US has shunned diesel for private vehicles. That has to change before any headway can be made.
I disagree. Diesel is a BYPRODUCT of gasoline refining. A barrel of oil (42 US gallons), when refined, yields about 19.5 gallons of gasoline and about 9 gallons of diesel. Part of the reason diesel prices got so expensive last summer is because there was no supply. Nobody was buying the expensive gasoline that accounts for more than half of all refined goods, but the big trucks and ships needed the diesel that nobody wanted to make because they couldn't sell the gasoline. Starting to see the vicious cycle? Therefore, if a bunch of people started driving diesel cars, you'd see last summer's diesel prices becoming a bit more permanent. Leave diesel to work vehicles. Cars should run on gasoline. The headway needs to be made in technologies like gasoline direct injection.
The irony is that hybrid diesels would be perfect, but nobody takes the concept to it's true potential.
Diesel electric all the way, like in train engines. A Diesel likes to have a constant RPM at it's peak performance value. Imagine connecting an alternator directly to the engine and giving up the inefficient gear system. Imagine a Diesel engine that is always at it's peak performance RPM, even when there's barely any electrical load on it. That car would be a rocket that goes for free (or almost free). It's also pretty easy to build if you have 2 things:
1) 1x 150kW alternator (it's the right amount) that also fits under the hood along with the engine.
2) 4x 40kW electric engines that you connect directly to the drive shaft (and should also fit in there somewhere).
As far as I know a 150kW alternator is very big (about as big as the engine itself) and the 40kW engines are also huge, but at least in theory this would be by far the best way to bring the top possible performance of an engine to the tarmac. Electricity is the best way to transfer energy between two points and a constant RPM diesel is the most efficient and performant diesel out there.
UNIX was not designed to stop you from doing stupid things, because that would also stop you from doing clever ones.
As another person replied, a series hybrid will never be more efficient than a straight engine, but that's ignoring the charging of the batteries through third party options like regenerative braking, solar collection and wall sockets.
It's also ignoring that the losses through conversion are only in the 5% to 10% range. If the gain from running the engine at a constant speed is enough to offset this loss, the hybrid *will* be more efficient.
But, I wanted socialized health insurance!
The GM diesel where sold to people that didn't know how to maintain them and by dealers that really didn't know how to maintain them. People that bought a 300D where used to paying Hans the big bucks.
My dad's 300D from 1982 has never required any sort of engine work. It's driven 300k miles on diesel and now 100k on vegetable oil. It's got the original transmission, the original suspension, the original brakes (this seems crazy to me, but they're in fine shape), etc. It doesn't have the original battery, filters have been replaced, and the vacuum system that controls the locks is leaky so if you shut down the car and lock/unlock cycle the doors a few times the other 3 doors will stop following the driver's door lock.
His 1994 Ford Explorer gets a new transmission every ~4 years, new brakes every 1.5 years, and required him to work on the engine for a week a few years ago. The brakes and transmission are no longer Ford parts - those failed even more often and the new brand has a lifetime warranty that gets a lot of use. The front suspension needed to be replaced, and when the brakes fail ahead of schedule (they do so by falling off while you're driving if you don't watch them closely enough to catch them a month in advance) there's a good chance you'll cause some damage requiring replacement of the axle if you have to tap the brake pedal as you get off the road.
Anecdotes, but along with similar experiences on 2 other Mercedes and 3 other American cars in this period, they're enough to make him look to the Germans when he wants a new car.
"I zero-index my hamsters" - Willtor (147206)
Why bother using a drive shaft? Put the 4 eletric motors at the wheels and just run electric wire to power them. Otherwise, I like your idea, it is probably overpowered for the normal driver, but a good idea.