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You'll notice from the sample chart above shows the best efficiency at low RPM and high load. Basically since the advent of fuel injection, engines have had complete combustion across the rev range. It's possible to pull a little more heat energy out of the combustion chamber and turn it into useful motion by increasing the expansion ratio, but for the most part efficiency increases come from reducing parasitic losses. Friction goes up exponentially with RPM, and at higher loads the ratio of useful work to friction is better. At higher loads you also have lower vacuum losses, so having adequate gearing to keep the engine at the lowest RPM possible with the highest load is important. A CVT is the best possible gearbox for this, because anything with fixed gear ratios will necessarily swing outside of the optimal efficiency range.
Additionally, many technologies like variable lift and timing don't increase peak efficiency, but they broaden the area under the curve where you can get high efficiency.
I just hope you are proven right in the long term. Technology will move forward in either case. Here's to 75 MPG internal combustion engines in the meantime.
period. Now with the partnership between China and Toyota building the Hydrogen stuff they could turn the entire car industry inside out if they are successful.
Better review "endergonic vs exergonic chemical reactions."
Quote:
Originally Posted by double6's
turbines
Good idea. That would solve our garbage problems too--- if you can light it on fire, you can use it as fuel. They made Andy Grannatelli illegal because he was too fast.
I just hope you are proven right in the long term. Technology will move forward in either case. Here's to 75 MPG internal combustion engines in the meantime.
There's a reasonable upper cap on fuel economy in a given vehicle. An engine can have zero parasitic losses and 100% combustion efficiency and you'll still only get a finite fuel economy, because you have to push a box through the air, rolling on sticky tires. Reducing air and tire drag is typically lower hanging fruit than upping engine efficiency at this point.
Smaller and more aerodynamic vehicles give a linear relationship with fuel economy. Lighter vehicles help with rolling resistance but aero is typically more important.
I'm so old, I remember when Michael Jackson was black. I covered the hard cold start problem in my post.
I also had to synchronize 12 Weber barrels and double, dual point distributors on 'Ferraris & Lamborghinis by ear. I'll stand by my original contention: new electronics haven't made that big a difference compared to their cost & complexity (not to mention unpredictability)....Pretty easy and cheap to remove a clogged carb jet and blow the dirt out. How long does it take to R&R a fuel injector? Can you do that on the side of the road?
I don't know how easy it is to R&R a fuel injector, in my 25+ years of driving fuel injected vehicles I've never had one go bad - that's part of why I think so highly of the design. Whenever an ancient carb'd vehicle passes by, I can smell the unburned fuel it leaves in it's wake. The difference in efficiency is staggering.
I'm not going to debate something that is so black and white. When FI came out every single vehicle went to it. There was no debating which was the superior design, it was simply a no brainer improvement, a monumental leap in vehicle technology. Go argue with yourself if you want, I'm done.
I say in this age of computers the drag coefficient and tire resistance are close to tapped out.
Quote:
Originally Posted by EckyX
There's a reasonable upper cap on fuel economy in a given vehicle. An engine can have zero parasitic losses and 100% combustion efficiency and you'll still only get a finite fuel economy, because you have to push a box through the air, rolling on sticky tires. Reducing air and tire drag is typically lower hanging fruit than upping engine efficiency at this point.
Thanks for the response, again you are right. How much has that finite fuel economy changed as per innovations over the last 40 years?
I say in this age of computers the cars drag coefficient and tire resistance are close to tapped out. We still haven't beaten the pot hole yet. Engineers have gone much further but only for demo, competitions and other short term purposes.
When real world automotive conditions are factored in the scale of that efficiency challenge chart goes straight up.
Does any one have any real numbers measuring the internal combustion engine's (power delivered efficiency's) over a time-line of the past 40 years? Thanks.
Also mentioned were some comments about subcompacts of Europe lighter cars, requiring lessor size compressors, evaporators and condensers which required not as much HP from the engine as the American's cars dealing with the more extreme climate's in the U.S. Add to that the high safety standards of our country and you can see the a pattern.
One of the many reasons that a our cars are simply bigger. Are our cars less fuel efficient, No. Cars in the U.S. have more stringent crash test requirements, larger air conditioner's requirements, and Interstate highways that require high speed entrances and longer distances traveled commonly in the U.S. The consumer decides what sells here and cars buyers vote with their purchases. The biggest selling cars speak volumes about what direction new technology is heading.
I don't think Euro crash tests are less stringent, just different. This article suggests that they are somewhat more stringent in some areas, somewhat less stringent in others, they focus more on safety for pedestrians for example.
There are plenty of high speed entrances to major roads in Europe too. The rate of auto accident deaths is actually lower in many (but not all) European countries compared with the US. Of course car design standards are not the only factor in that but also road design, driving habits etc play a role.
Europe sucks at efficiency and innovation.
The answer to efficiency for decades was:
1) make it diesel
2) make it tiny
3) make it manual.
It’s no surprise they’re in last place with EV and hybrids. They’re very primitive.
Dead last? Compared with Latin America, Middle East, Africa, South Asia, Australia etc? I think the country in the world with the highest market share for EVs is Norway, and there are plenty of EV models from European manufacturers with new ones being released all the time.
Does any one have any real numbers measuring the internal combustion engine's (power delivered efficiency's) over a time-line of the past 40 years? Thanks.
No chart like that, but check out Ecomodder's BSFC wiki page. You can look at the absolute efficiency of various motors people have found charts for and get at least a rough idea.
For what it's worth, Honda's 1.0L released in 2000 kept the efficiency crown until the Accord Hybrid's 2.0 barely passed it, and that engine still holds the record. The G1 Insight engine from 19 years ago is still more efficient than, say, Mazda's Skyactiv engines, which they advertise as being highly efficient.
Diesels typically have lower BSFC than gas engines but that's primarily due to deisel having more energy per gallon, and secondarily because most diesels have higher compression and no throttle butterflys.
Remarkable strides have been made in both aerodynamics (reduce drag and noise) and engine efficiency. The glaringly missing factor is weight. Today's cars are heavy. Partially that's safety-regulations, partially consumer-preferences, and partially... who knows. If I were the efficiency-czar today, my emphasis would be on reducing vehicle weight.
Why can't we have a compact 4-seater sedan that weighs 1800 pounds?
The lighter the car, the smaller of an engine it needs, for the same acceleration. Smaller brakes. Smaller gas-tank. Lighter suspension-members. Smaller bearings, thinner subframe, and so on. Some safety-related factors don't necessarily scale down. Maybe the windshield can't be made thinner, or the seat-belt attachment points less sturdy. But most structural things and mechanical things scale down in symbiotic relationship, as overall mass decreases. That, I think, is the better route for less fuel-usage and lower emissions, all while retaining (or even increasing) performance!
City cars are an afterthought to European makes, they sell more executive class cars and what's considered efficiency is something that returns desirable fuel economy at high cruising speed where 85-90mph is the average and everything that isn't performance or executive class cars falls under that.
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Originally Posted by nedergras
Last time I went, Kia became really popular in Europe... I couldn't believe it. But in Holland the Dutch are totally different from the Germans, more Hondas like Accords where in Germany I never saw any except the euro Accords and a Jazz once, I don't remember any Civics. But before my last trip I remember that 1st gen Kia Sorentos were popular before Kia started eating more market share.
As was mentioned, small city cars are the mainstay of most European manufacturers, the VW Golf had been the biggest selling car in Europe for a long time I think, plus there's also the small cars from the French manufacturers, Fiat, Mini etc and even BMW/Mercedes/Audi have small models which I don't think are sold in the US.
Kia is pretty popular, between that brand and Hyundai they have a European market share over 6% which is more than any of the Japanese groups. Japanese premium brands are not very popular in Europe, Lexus had a very low market share compared with premium Euro brands, Infiniti is pretty much invisible for market share and Acura doesn't exist at all.
Latest market share/sales figures.
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I say in this age of computers the drag coefficient and tire resistance are close to tapped out.
