engines

[highteknology]

i don't know if this is the right place to put this so the mods can move it if they feel like they should.

anyways, i was thinkin today that one day we will run out of oil. there's no denying it. if we don't pursue electric vehicles or other ways to run cars that do NOT require the use of oil. i started to think, is there a diesel/hybrid vehicle on the market or a concept car? has anyone ever thought of making one? i was thinking that if they are going to be made or something, then in theory couldn't you buy the modification kit to make the diesel engine run on vegetable oil? that way it would not require oil for the gas part of the car. you would still need oil to lubricate parts though but it's one more step. any thoughts?

[PlayStation3]

they do make electric cars. 2 they is a prtotype of a hydrogen car, and most desials can run on more then desial ie: bio desial which is made from heated up shorting/ veggy oil.

[beef_bourito]

I believe there is a diesel hybrid on the market, i heard about one a while back but i don't remember who made it. it is very possible to make it and it makes much more sense that a gasoline hybrid because diesels are already better for gas mileage.

[drdisque]

the problem with a diesel hybrid is that they make no power up at the top of the powerband as both diesel and electric motors are high-torque, low horsepower.

the gas-electric engine is better balanced.

There currently are no commercially produced diesel-electric hybrid cars.

[beef_bourito]

but horsepower doesn't really matter when you're looking for fuel economy. i'd say it's a better idea than a gasoline-electric hybrid in terms of fuel economy. now i don't really think hybrids are all that great but that's a completely diffrent discussion.

[KiwiBacon]

There are a few prototype diesel hybrids, but no production ones.

One issue that needs to be worked through is the oil supply to the turbo. The engine might be required to start and stop often while the turbo has to be kept cool while spooling down.
A seperate oil supply would keep it spinning, but it's more space and cost.
Of course an idling diesel doesn't use as much fuel as an idling petrol so maybe keeping them running is an option.

IMO petrol hybrids are just practice, there's no point when a straight diesel powered car is more efficient, more economical and doesn't need the space penalty, weight and cost of a battery pack.

A diesel hybrid could get truely impressive fuel economy around urban areas, but on the open road hybrids are a lose-lose situation.

[Kurtdg19]

Originally Posted by KiwiBacon

There are a few prototype diesel hybrids, but no production ones.

One issue that needs to be worked through is the oil supply to the turbo. The engine might be required to start and stop often while the turbo has to be kept cool while spooling down.
A seperate oil supply would keep it spinning, but it's more space and cost.
Of course an idling diesel doesn't use as much fuel as an idling petrol so maybe keeping them running is an option.

IMO petrol hybrids are just practice, there's no point when a straight diesel powered car is more efficient, more economical and doesn't need the space penalty, weight and cost of a battery pack.

A diesel hybrid could get truely impressive fuel economy around urban areas, but on the open road hybrids are a lose-lose situation.

I agree. A hybrid diesel engine doesn't make as much sense as a hybrid gasoline engine mainly due in the nature on how these engines work. The hybrid technology has its greatest benefits during urban commute where you will experience more "stop and go" traffic. Even though this would probably still benefit the consumption of fuel in a diesel setup, the benefits would actually be smaller compared to a gasoline hybrid since diesel engines run at a higher efficiency during lower engine speed. Diesel engines are simply more efficient all around, and it would not have as big of a savings compared to a gasoline hybrid setup.

And even then......the most efficient hybrid cars like the Toyota Prius for instance still come at a price premium that doesn't quite compensate its added cost at the pump compared to most fuel efficient non hybrid vehicles, that is, unless you plan on keeping them for over 100+k miles (and even then, a diesel engine would still more than likely be the winner).

[KiwiBacon]

Originally Posted by Kurtdg19

Even though this would probably still benefit the consumption of fuel in a diesel setup, the benefits would actually be smaller compared to a gasoline hybrid since diesel engines run at a higher efficiency during lower engine speed. Diesel engines are simply more efficient all around, and it would not have as big of a savings compared to a gasoline hybrid setup.

But the energy stored and returned (by the electric braking and acceleration) during a stop-go scenario would be the same regardless of which fossil fuel is powering the vehicle.
So wouldn't the percentage of fuel saved be the same?

[SaabJohan]

Originally Posted by highteknology

i don't know if this is the right place to put this so the mods can move it if they feel like they should.

anyways, i was thinkin today that one day we will run out of oil. there's no denying it. if we don't pursue electric vehicles or other ways to run cars that do NOT require the use of oil. i started to think, is there a diesel/hybrid vehicle on the market or a concept car? has anyone ever thought of making one? i was thinking that if they are going to be made or something, then in theory couldn't you buy the modification kit to make the diesel engine run on vegetable oil? that way it would not require oil for the gas part of the car. you would still need oil to lubricate parts though but it's one more step. any thoughts?

Diesel engines are much more efficient than gasoline engines at part load and since the main reason for a hybrid is inefficiency at low loads the benefits of a diesel-hybrid would be smaller. Given the extra energy required for manufacturing, recycling and the increase in fuel conusmption caused by the extra weight diesel-hybrids aren't that beneficial.

We also wont run out of oil, the problem is that there will come a time when the oil is so expensive that we really can't afford it as an option.

Run diesels on vegetable oil isn't a good idea either, the emissions aren't that good but more importantly vegetable oil can never replace fossil fuels, we can't simply make enough of it. We can use the vegetable oil that we currently have, this oil is best used by converting it into esters which are added to diesel fuel in a small amount.

Today we use huge amounts of fossil fuels and to replace these won't be simple. To replace all fossil fuel we essentially have to build 10,000 new powerplants (hydro, nuclear and similar) of the largest size currently possible.

[KiwiBacon]

Originally Posted by SaabJohan

Diesel engines are much more efficient than gasoline engines at part load and since the main reason for a hybrid is inefficiency at low loads the benefits of a diesel-hybrid would be smaller. Given the extra energy required for manufacturing, recycling and the increase in fuel conusmption caused by the extra weight diesel-hybrids aren't that beneficial.

That's not true at all. Especially your claims about an increase in fuel consumption due to the extra weight.

The energy reclaimed in braking and released on acceleration by the hybrid system is the same regardless of what type of IC motor is bolted in. Hence the overall energy savings are the same.

Hybrid diesels haven't been released for sale because they're harder to make. Research diesel hybrid vehicles are out there as cars, light trucks and heavy trucks.

[SaabJohan]

Originally Posted by KiwiBacon

That's not true at all. Especially your claims about an increase in fuel consumption due to the extra weight.

The energy reclaimed in braking and released on acceleration by the hybrid system is the same regardless of what type of IC motor is bolted in. Hence the overall energy savings are the same.

Hybrid diesels haven't been released for sale because they're harder to make. Research diesel hybrid vehicles are out there as cars, light trucks and heavy trucks.

With a hybrid system the main advantage is that it makes it possible to run the internal combustion engine at a higher load, where it's more efficient. Since the loss of efficiency at part load of a diesel is smaller than on a gasoline engine the benefit of a diesel hybrid system is smaller.

Regenerative braking is more of a bonus with the electric hybrid system as electric motors can be used as generators. However, battery systems have difficulties with the high amps generated by regenerative braking so the efficiency isn't that high. For a pure braking energy recovery system there are other options, both flywheels and supercapacitors are much better than batteries to store large amount of energy when the charging rate is high.

Hybrid or not, if you increase the weight of any car the fuel consumption will go up, generally by 0.3-0.5 liter/100 km per 100 kg extra weight.

Currently all hybrid vehicles have an energy consumption per mile that is higher than an equally sized conventional car, the energy required to manufacture, maintain and recycle the hybrid system is higher than the energy saved by it in the form of fuel. With a diesel the saving caused by the hybrid system will be even smaller so currently I don't see any real benefits with it!

[KiwiBacon]

Originally Posted by SaabJohan

With a hybrid system the main advantage is that it makes it possible to run the internal combustion engine at a higher load, where it's more efficient. Since the loss of efficiency at part load of a diesel is smaller than on a gasoline engine the benefit of a diesel hybrid system is smaller.

Regenerative braking is more of a bonus with the electric hybrid system as electric motors can be used as generators. However, battery systems have difficulties with the high amps generated by regenerative braking so the efficiency isn't that high. For a pure braking energy recovery system there are other options, both flywheels and supercapacitors are much better than batteries to store large amount of energy when the charging rate is high.

Hybrid or not, if you increase the weight of any car the fuel consumption will go up, generally by 0.3-0.5 liter/100 km per 100 kg extra weight.

Currently all hybrid vehicles have an energy consumption per mile that is higher than an equally sized conventional car, the energy required to manufacture, maintain and recycle the hybrid system is higher than the energy saved by it in the form of fuel. With a diesel the saving caused by the hybrid system will be even smaller so currently I don't see any real benefits with it!

Hybrids only have a fuel economy advantage in stop/go situations. The regenerative braking is the major way to save fuel in an urban environment.
In open road situations a hybrid is at fuel consumption disadvantage compared to a conventional vehicle powered by the same IC engine.

Compare the energy required to accelerate a car to 50km/h (approx 150 kJ) vs the power required to cruise at 50km/h (less than 10kw).
Each stop/go cycle is a major drain. You can expect fuel consumption to increase linearly in stop/go situations as weight increases.

Running the engine at a higher load can be achieved without a seperate electric motor/generator and battery pack. But it's a redundant argument as diesels are more efficient than petrols in their entire load/speed range.

Are you aware that BMW's diesels weigh only a fraction (6kg for example) more than their equivalent petrol?
Your extra weight comment is groundless, especially in a car carrying around a few hundred kg of battery.

The fact that conventional diesel cars already beat petrol/electric hybrids for combined cycle fuel economy indicates the petrol/electric cars are only a stop-gap measure.

[SaabJohan]

Originally Posted by KiwiBacon

Hybrids only have a fuel economy advantage in stop/go situations. The regenerative braking is the major way to save fuel in an urban environment.
In open road situations a hybrid is at fuel consumption disadvantage compared to a conventional vehicle powered by the same IC engine.

Parallel/serial hybrid system as used by for example Toyota still have a fuel consumption advantage during highway driving, but the advantage is much smaller. A serial hybrid system may have a disadvantage though as the efficiency of such a hybrid system usually is 55% or lower.

Originally Posted by KiwiBacon

Compare the energy required to accelerate a car to 50km/h (approx 150 kJ) vs the power required to cruise at 50km/h (less than 10kw).
Each stop/go cycle is a major drain. You can expect fuel consumption to increase linearly in stop/go situations as weight increases.

The performance of regenerative braking in current hybrids are not especially good (I've heard about efficiencies in the area of 30% or lower but I can't verify that). If regenerative braking is the main goal of the hybrid system there are better ways to do it with a lot less extra weight. There are also conventional engines that has a "light version" of this system, they simply recharge the battery with the alternator during braking (then shutting off the generetor during load, when possible). There are also simpler systems with a small motor/generator built into the flywheel which can recover energy during braking. For a pure regenerative braking purpose the battery/supercapacitor can also be made a lot smaller/lighter since it doens't need to store that much energy. Flywheel storage is also an option that will be light and more importantly, it can handle the high recharge rate needed.

Originally Posted by KiwiBacon

Running the engine at a higher load can be achieved without a seperate electric motor/generator and battery pack. But it's a redundant argument as diesels are more efficient than petrols in their entire load/speed range.

If you want to run an engine at higher load without a hybrid system you have limited options; you could use a different gearing or you can downsize the engine. Hybrids commonly downsize their engines too, then they use the electric motors to compensate for the powerloss. Conventional drivetrains usually compensate the power though turbo or supercharging.

On a hybrid system the engine can simply be shut down during low load conditions that mostly occur during urban driving.

How the engine is used is a major reason for fuel saving of a gasoline-hybrid but it will be a minor reason for fuel saving for a diesel-hybrid. In other words, the diesel-hybrid will not be that much better than a conventional diesel when it comes to fuel consumption. The conventional diesel will then require much less energy for production/maintenance/recycling so in overall it will be a better option. At least in the near future.

Originally Posted by KiwiBacon

Are you aware that BMW's diesels weigh only a fraction (6kg for example) more than their equivalent petrol?
Your extra weight comment is groundless, especially in a car carrying around a few hundred kg of battery.

With a given output diesel engines does not only weigh 6 kg more than a gasoline engine, and BMW's diesels aren't that light since they still use conventional iron in their engine blocks.

The weight of the battery pack is no exception. The weight of the complete hybrid drivetrain must be compared with the weight of a complete conventional drivetrain. The one that is heavier will see an increase in fuel consumption due to this reason. This means that a hybrid system, if it's heavier than a conventional drivetrain must offer other fuel saving advantages to overcome the weight disadvantage.

Originally Posted by KiwiBacon

The fact that conventional diesel cars already beat petrol/electric hybrids for combined cycle fuel economy indicates the petrol/electric cars are only a stop-gap measure.

Just because diesels show a very low fuel consumption in conventional drivetrains does not mean that we will see the same fuel consumption reduction as the gasoline engine achieved as a hybrid. A diesel is already so efficient at part load that there isn't much room for improvement here. This essentially leaves the regenerative braking as the only advantage with diesel-hybrid system.

[adelie]

Originally Posted by highteknology

i don't know if this is the right place to put this so the mods can move it if they feel like they should.

anyways, i was thinkin today that one day we will run out of oil. there's no denying it. if we don't pursue electric vehicles or other ways to run cars that do NOT require the use of oil. i started to think, is there a diesel/hybrid vehicle on the market or a concept car? has anyone ever thought of making one? i was thinking that if they are going to be made or something, then in theory couldn't you buy the modification kit to make the diesel engine run on vegetable oil? that way it would not require oil for the gas part of the car. you would still need oil to lubricate parts though but it's one more step. any thoughts?

Last fall I started pondering this same question. I wanted to start a company, making Electric cars, but I figured i'd ease into it . . .
so would like to make awareness of a my start-up company, Alternate Propulsion Motor Co. This company is gearing up to create hybrid / EV conversions for existing vehicles. The idea is to replace the cars internal combustion engine with our own gas-electric hybrid, PHEV, or Full electric.

We are currently engineering our prototypes and preparing our products to meet your needs. Our goal is to have products available by late 2007. We would like your input as to best accomplish this.

Anyone reading this is invited to participate in our Hybrid Vehicle Conversion Survey, located at http://alternatepropulsion.com/index.php?page=3. This will give us ideas on how to better engineer our products.

Be honest, and let us know what would best serve the future hybrid/automotive community.


Thanks.

- Dave

[KiwiBacon]

Toyota have completely worked every aspect of the prius to get any fuel economy advantage they can.
From special tyres with a lower rolling resistance, to the atkinson cycle engine with bores offset to the side of the power stroke.

A prius without the battery pack and generator would do better on the open road than a hybrid prius.

Originally Posted by SaabJohan

This essentially leaves the regenerative braking as the only advantage with diesel-hybrid system.

Duh. Just like every other hybrid.