Here's the thing.
Hybrid technology is a band-aid. It is used to boost output and efficiency of engines that would otherwise be considered a joke. The Prius has an engine that is 1.8 liters and only puts out 98 horsepower. That's barely 50hp/liter. If that was put in any other car, it would be shunned by the automotive community. However, because it has a "Hybrid Synergy Drive" badge on the back and a battery wedged in beside it, it gets a pass.
Moreover, the engine is not even the major player in the Prius' above-average fuel economy. Consider this: the Lexus CT200h has the same powertrain, CVT and all, and yet can only achieve mileage that is 80% of what the Prius does. So what makes the difference? Well, they're not under the skin, in fact, most of them are on the skin somewhere. Things like major aerodynamic work and low rolling resistance tires are the kind of primping and preening the car went through before it was allowed to step out into the world as Toyota's "God car". There's nothing to say that a well developed, modern, pure-gas powerplant with those other modifications and that much work would not do the same numbers.
The only place the hybrid methodology has anything over on other powerplants is in the city. With a sensitive start/stop system and the ability to drive slowly (read: crawl) on pure electric power, your fuel economy is practically infinite for the available range. However, should you get that horrible urge to put your foot down, it becomes no better than anything else. Which means that you have to change your driving style to get any major advantage out of your shiny hybrid batteries. And if you're going to go through all that trouble, why not do it for a car that still has guts when you want to romp on it?
And that, that's the thing.
-Shawn
Well, first, your volumetric consideration is kind of irrelevant. Who cares if the Prius's 1.8 L Atkinson cycle gets fewer hp/cc than a more tightly wound regular Otto-cycle motor? Except in racing or in those countries with involved auto tax laws, nobody cares if you have a 225-pound 1.8 L engine with 98 hp or a 225-pound 1.2 L engine with 98 hp. And the fact is, the Atkinson engine gives you better thermal efficiency than the Otto, provided you can deal with its limited rev range, and that's where the Aisin CVT and the hybrid boost come in.
ReplyDeleteAnd regarding speed, my wife's '12 Camry Hybrid up and flies when you stomp the good pedal hard. Seriously. In a flat-out drag race against my '04 Miata (I know, I know, hardly the Race O' Champions) I'm pretty sure it would blow my doors off.
Oh sure, when you do the un-green thing and stomp it, it does diminish the short-term mileage and make the scrolling histogram on Toyota's patented Distracto-Vision Teevee Screen get a big sad slump in it. But when that traffic light finally turns green and behind you there's a mile-long line of anxious commuters trying to get the Hell to work, a decent respect to the opinions of mankind requires that you sacrifice a few milliliters of gas and step briskly forth. Which, as I said, it can and does; the limiting factor is the tires. (Don't get me started on the ridiculous tires Toyota insists on shipping their otherwise well-fitted cars with! Even the GT-86 comes stock with crappy rubber.)
Yes. In the Camry Hybrid it might be that way. But that's a 200hp, very much less efficient horse of a different color. I think for Comparison we should look at the Passat or Jetta TDI. Pick your poison, they both do the similar numbers to the Camry. And that's the EPA. I've seen normal TDI drivers coming in reporting 40+ mpg average. And remember, these cars don't have the tricks or tires the hybrids have either. I just can't get behind an inferior engine design like that.
ReplyDeleteHonestly, we need to forget about hp/liter. The most uninformed automotive opinions on the internet seem to all hinge around the idea that the number tells you how "good" an engine is. A far better metric would be a set of efficiency numbers, showing fuel consumption at various power output levels. Or even the power/weight ratio of the engine/support systems if you are looking at performance.
ReplyDeleteI think it's a solid measurement as a starting point. If an engine has the kind of efficiency to put out on those levels, it is just a downtune away from superior economy.
DeleteI think it would take a lot more then a timing/air fuel change to make a Ferrari efficient.
DeleteAre you sure about that? If we start with the high-strung 100hp/l version and work backwards, you would eventually hit something resembling good fuel economy. But the opportunity cost is too great for the average Ferrarri buyer.
DeletePretty sure, you would also need to adjust your cams to allow a longer burn at lower speeds, lengthen intake/exhaust runners to resonate at lower engine speeds and boost every day drivability/efficiency. Then swap in smaller injectors so that you can have a finer fuel vapour entering the engine allowing for a more complete burn at partial throttle, then add some inertial weight to the flywheel so you aren't required to floor it everytime you encounter a hill.
DeleteHmmm also, you would be operating on a leaner ratio, this would mean you need a better cooling system since the engine isn't being cooled by excess fuel, and is operating near stoic.
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