Why are most hybrids based on gasoline engines?
Why are most hybrids based on gasoline engines?
(OP)
Why is it that car companies are pitching gasoline-based hybrids as alternatives to diesel vehicles? Surely a diesel-hybrid has a similar advantage over a gasoline-hybrid as a diesel has over a gasoline?
Sure you can downsize your gasoline engine and run it more efficiently - possibly even without a throttle. But even then it's still going to be less efficient than a diesel as the main power source in a hybrid.
Or is it simply image? Hybrid=high-tech, Diesel=low-tech. Ergo, hybrids cannot use Diesel engines.
Sure you can downsize your gasoline engine and run it more efficiently - possibly even without a throttle. But even then it's still going to be less efficient than a diesel as the main power source in a hybrid.
Or is it simply image? Hybrid=high-tech, Diesel=low-tech. Ergo, hybrids cannot use Diesel engines.





RE: Why are most hybrids based on gasoline engines?
I agree, a diesel hybrid would be a much better idea, how do they handle being started and stopped repeatedly? I can imagine there would be emissions problems.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Why are most hybrids based on gasoline engines?
I'm not 100% sure about the emissions issues, but stop-starting a diesel is pretty simple, because of the fact that the diesel will be DI rather than port-injected, so there are no "bad" cycles.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
Diesel gives less HP per pound therefore less performance.
RE: Why are most hybrids based on gasoline engines?
Ethanol<Gasoline<DieselFuel
RE: Why are most hybrids based on gasoline engines?
Given the extra weight of batteries in a hybrid, the rest of the powertrain has to go on a diet to keep the vehicle weight anywhere near acceptable.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Why are most hybrids based on gasoline engines?
I think that if I were going to make a ICE/electric hybrid I would try to use something completely new.
What is the best method to turn gasoline/diesel fuel into rotational energy to spin an alternator? thermodynamically speaking. This ICE would also have to be quick starting an stopping, while not suffering large efficiency losses and emissions problems. there should be an optimization of the differing goals.
This might of course just leave us with the answer that was given about most efficient ICE: It depends.
IE: Turbocompounded diesels won that discussion with apprx 50% thermal efficieny. But in this case the power to weight ratio is not very high. While turbines might be relatively light weight, they probably dont like to start and stop all the time, and have their torque peak at stall.
RE: Why are most hybrids based on gasoline engines?
Markets don't wait for compounded development cycles.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Why are most hybrids based on gasoline engines?
The Blacksmith has pointed out the purchase price premium of diesel vehicles, so from a marketing perspective a US consumer willing to pay extra for the different technology of a hybrid (i.e. Prius, Civic, soon Accord) might also be considering a diesel (Golf, Jetta, Passat).
RE: Why are most hybrids based on gasoline engines?
Most new TDI diesels don't make any more noise than a conventional gasoline engine in the low to mid RPM range.
After all it's not for racing purposes.
RE: Why are most hybrids based on gasoline engines?
I guess it's both.
Japanese OEM's have never really been that big on Diesels in the passenger car market. And they do excel in small, efficient gasoline engines, which are ideal for hybrids.
And I keep reading in the automotive engineering press that the advent of the hybrid in the US will kill off any future for diesels in that market.
Does diesel really command a $5000 premium over gasoline in the US? That's amazing - the difference is nothing like that in Europe for passenger cars (<$1000 difference generally).
RE: Why are most hybrids based on gasoline engines?
Go to any of the big three's auto web sites and click on the build your own - first you must select a 3/4 ton pickup; F250SD, Ram 2500 or C/K 2500, which in itself costs more then the 1/2 ton pickups, then check the retail cost for the diesel option, it is right at or over $5,000. BTW, I work with big diesels and if the price difference was like Europe, I've have a diesel pickup, but I can buy a lot of gas for my 4.6 Triton for $5,000.
RE: Why are most hybrids based on gasoline engines?
I forgot that you were probably refering to agricultural vehicles. The UK press often call them "Chelsea Tractors" here.
In the passenger car world, there aren't many diesels to choose from in the US. However, I did find that the list price of a Mercedes Benz E-class diesel is about $1000 more than the equivalent gasoline (E320 CDI - $51800, E350 - $50800). Not that different from Europe after all. I know which of the two I'd rather have.
RE: Why are most hybrids based on gasoline engines?
European car manufacturers are betting on the diesel.
There is a whole array of frugal consumption, low-noise, high-speed plus impeccable emission diesel engines that are being offered as alternatives to petrol-engines on a great deal of car models.
At the high-end of the market, Mercedes, Audi and BMW have introduced state-of-the-art diesel engines that are simply outstanding from any perspective.
RE: Why are most hybrids based on gasoline engines?
1) Hybrid is great for Japanese 10-15 cycle which has a lot of part throttle conditions. Therefore, it's suitable for Japanese market. Diesel powered cars on the other hand are not allowed to enter Tokyo city, it's a no no to have hybrid with diesel engine
2) diesel engine is not so good at high rpm. It is also heavy and requires bigger displacement for higher horsepwer. In this case, gasoline is favored for higher output and great for highway driving whereas electric motor will take care of the city driving
Honda has a 2.2 L TC diesel with Aluminum block. Good job by Honda considering it's their first diesel engine
RE: Why are most hybrids based on gasoline engines?
Here are the reasons for no diesel in the US for hybrids (in my opinion):
1. No low sulfur diesel fuel available in the US until 2006
2. US emissions regulations are written such that NOX emissions are heavily penalized compared to European regs. This makes meeting the US emissions regs a big development program for a diesel, especially when low sulfur diesel fuel is not available. Much easier to meet US emissions regs using a gasoline engine.
3. Toyota & Honda do not have much experience with diesels in passenger cars. European automobile manufacturers do have lots of diesel passenger car experience.
I would be pleased to see the Mercedes "bionic concept car" (diesel engine, not a hybrid) reach production. The claimed fuel economy for it is 84 MPG on the combined US test cycle.
j2bprometheus@aol.com
RE: Why are most hybrids based on gasoline engines?
Blacksmith
RE: Why are most hybrids based on gasoline engines?
Your reason #2 is right on. They are doing all sorts of things like exhaust recirculation to lower NOx. This drops the efficiency advantage of the diesel.
The diesel took over large trucks because of its efficiency. It took over agriculture because of efficiency and the diesels pull better. But we have stumbled in getting them into light trucks and automotive. With present emission standards they probably will never supplant the computerized si catalyst engine in automotive.
Tell me, Why are we stuck on high molecular weight diesel fuel? It seems like the particulate level would be improved it we ran diesels on lighter fuel similar to a gasoline cut. Of course it would not be necessary or desirable to include additives and refining methods to increase octane. They would run on straight paraffins similar to the crude before modification.
RE: Why are most hybrids based on gasoline engines?
Diesel oil provides it's own lubrication in the injector/pump so wear in minimal.
A pump for none self lubricating "gasoline" to several thousand psi is probably not easy to design.
RE: Why are most hybrids based on gasoline engines?
Low sulfur diesel fuel is not yet widely available in the US.
Go down to the fuel station near where you work, take a small sample of diesel fuel & have it tested. I'll bet that the test will indicate that the sulfur is high.
Automakers want consistent fuel all across the US. The EPA will not allow them to sell a vehicle that relies on low sulfur diesel fuel until low sulfur fuel is the only transportation fuel available in the US.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
To my opinion there are several reasons to choose a gasoline engine in a hybrid car, but also some reasons can be found to choose Diesel!
Diesel cars develop a relative high torque, but a relative low amount of HP. In a hybrid car power is needed, because the torque is already supplied by the electric motor.
A turbo would solve this problem, but will only be effective a (relatively) high revs. A turbo doesn't like to start and stop continiously either.
Both Toyota (2.2 upto 175hp) and Honda (2.2) have excelent Diesel engines at the moment, so that will not be the reason to choose Gasoline.
The somewhat narrow view (to my opinion) of some people on Diesel engines is not completely correct. Carbon particle filters and catalic converters decrease the emision of modern Diesel powered cars enormously. Turbo charged Diesels have equal power, much more torque and a much better km/l (MPG) than Gasoline cars.
Ouside the US the development of the Diesel engine hasn't stopped....
Still the question remains... what is the best type of engine for a hybrid car..?
I'd choose (as Honda and Toyota did) a small gasoline engine with a high power (not torque) to weight ratio..
grtzz, Geert
RE: Why are most hybrids based on gasoline engines?
The main reason we don't have diesel hybrid cars at this point, IMHO, is that with the price premium of a hybrid already too high, a additional $1000 for the diesel puts it out of the question. Add to that the weight, emmisions & public preception (in USA) and I'm sure the marketing guys went with the safer bet (again in USA). Europeans actually prefer the diesels over the gas engines but their tax structure is heavily biased toward diesel so they have had decades of favorable experience.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
I guess the ideal would be a diesel hybrid running on vegetable oils, no co2 probs......
Ken
RE: Why are most hybrids based on gasoline engines?
It is probably a wash in terms of numbers of hybrid projects going on now. In terms of total number of vehicles in the hands of consumers, gas wins for now.
Best regards,
Matthew Ian Loew
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Why are most hybrids based on gasoline engines?
A gasoline engine is less expensive to produce than a diesel engine. A hybrid drive train, with its electric motor and batteries, is already more expensive to produce than a conventinal drivetrain. Adding the more expensive diesel engine option would make the hybrid cost prohibitive.
Of course, if one were to figure out a way to reduce the manufacturing cost of a recip diesel engine, then it becomes an economically feasible proposition. I've been working hard on this.......
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
Gas engines develop maximum torque at high rpms, while electic motors have max torque at zero rpm. Gas engines are also not very efficient at idle. So, for stop and go driving, the electric motor complements a gas engine very well.
Diesel engines, on the other hand, develop maximum torque at much lower rpms compared to gas engines, and they are much more efficient at idle because they can run so much leaner. Combine those two characteristics with the inherently more fuel efficient nature of compression ignition, and it becomes apparent that an electic motor would not give you the necessary gains in a diesel powered vehicle to justify the added cost and weight.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
Toyota say they are working on 10 hybrids. Maybe they are looking at a diesel electric.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
I used to travel from London to Plymouth almost every week on a massive diesel-electric hybrid. Why would the rail operators use diesel as the power source if it wasn't optimal?
RE: Why are most hybrids based on gasoline engines?
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Why are most hybrids based on gasoline engines?
Just like i mentioned before, the market perception toward diesel engine also carry weight when it comes to decision making on whether a diesel or gasoline for hybrid vehicle would be better.
RE: Why are most hybrids based on gasoline engines?
Gas and electric just seem to complement each other so very well. Sorry diesel lovers.
Life is what happens while we're making other plans.
Wally
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
Too much weight penalty having diesel hybrids, I'll bet hybrid car engineers would give their right arm for a spare 20kg for more battery
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
Odd, Toyota Australia's site does not list any diesel options for Avalon or Camry (their medium/large cars). Autospeed doesn't list any secondhand ones.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Why are most hybrids based on gasoline engines?
RE: Why are most hybrids based on gasoline engines?
OTOH, 0-60 timies do not matter in a bus, where efficiency and longevity do. Diesels can go 500K miles before a rebuild and are more efficient during cruising than a gas job.