Archive for the ‘Internal Combustion Engines’ Category

Fake Hondas

August 23rd, 2010 Comments off

When Hyundai entered the North American auto market in the mid-late’80’s, my initial impression was, “Who are they fooling?!  Nobody’s going to mistake that piece of crap for a Honda!”  I assumed, given the similarities in their name – and their cars’ badging – that they were attempting to capture the segment of the car market made up of consumers who thought they were buying a Honda weren’t capable of thought.  Consumers quickly realized that Hyundais weren’t Hondas, however.  Honda had gained a reputation for well-built, reliable vehicles, while Hyundais were quickly discovered to be poorly built, unreliable, and basically not worth the low price in their window stickers.

That was twenty years ago. So, what’s changed since then?  Well, Hyundais have.  After a few faulty starts, they’ve successfully moved into the luxury market with the Genesis.  They’ve also legitimately moved into the performance market with the Genesis Coupe.  And now, they’ve created the 2011 Sonata – a high-feature car for the masses that’s actually quite attractive.  They hired IAV Automotive Engineering (whose clients also include Bentley) to help them trim weight from the Sonata.  Since the car is only available with a 4-cylinder, the engine cradle structure didn’t have to be designed to accommodate any optional V6 – allowing a reduction in mass that translates in weight reductions elsewhere (such as the braking system) without a performance compromise.  (I love whole-systems thinking!)  All of this results in a car that has a little more power than a similarly featured Honda Accord (its most direct competitor), gets slightly better highway fuel efficiency (35 vs. 34 mpg), weighs approximately 100 pounds less, and is arguably more attractive.  The fact that the Sonata combines the impressive 200 horsepower 2.4 liter 4-cylinder (with continuously variable valve timing) with a 6-speed automatic transmission, and an SE trim-level that actually comes with performance goodies like stiffer springs, better shocks, and larger anti-roll bars, makes the $2k discount relative to the Accord all the more impressive.

A 10-year, 100,000 mile powertrain warrantyInitial Quality Ratings at the top of their class? What’s not to like? …Well, there’s that whole “no available V6” point where Honda has the advantage.  Then again, the 274 horsepower 2.0 turbo due out later in the model year should fix that.  And still reach 34 mpg.  …A fake Honda indeed!

2011 Hyundai Sonata

Technical Minutiae

November 9th, 2009 Comments off

When it comes to cars, I’m fascinated with technical minutiae.

In the tech Q&A section of one of the car magazines I read, the question was recently posed, “Are there any disadvantages to direct-injected engines?”  Many automakers are switching from port-injection to direct-injection in an effort to increase performance and fuel-efficiency.  (What’s the difference?  In traditional port-injected engines, fuel is squirted into the incoming stream of air before it goes past the intake valve into the combustion chamber where it is ignited.  Direct-injection, on the other hand, involves injecting the fuel directly into the combustion chamber – and air is the only thing that enters via the intake port.)  Direct-injection is used in many high-end and mainstream vehicles now, and will probably make its way further down-market very soon.

MicroscopeTurns out, there are a couple of concerns with direct-injection that aren’t immediately obvious.  One involves the intake valve itself.  Along with the air that flows past it is the small amount of gases that leak past the piston-rings and into the crankcase, returned into the intake stream via the PCV (positive crankcase ventilation) valve. This is essentially the “oily” air that resides in the bottom half of the engine.  Over time, the PCV system could cause oil-residue to build up on the back-side of the intake valve.  In an older port-injected engine, the gasoline washes this residue away, but in a direct-injected engine, this residue never gets cleaned off.  (Ford solved this problem by adding an additional filter to the PCV system.)  Another concern is that directly injecting gasoline into the cylinder could wash the oil-film from the cylinder walls, increasing wear of the rings.  My guess is that this will turn out to be a non-issue, given the amount of testing that goes into proving the fundamental combustion processes of engine technology.  But this is what I find fascinating – there are significant repercussions to even slight design modifications.

It’s sort of the law of unintended consequences.  (Increased ethanol production caused a spike in the price of tortillas, anyone?)  Not long ago, I had a conversation with an automotive engineer that was studying the role that lubricants (i.e., your motor oil) play in auto emissions – a role that is increasing as vehicles become more fuel-efficient.  Motor oil formulations have been (and will continue to be) altered in order to reduce their contribution to tailpipe emissions.  As an example, the amount of zinc dialkyl-dithio-phosphate (ZDDP) was recently reduced in engine oils, due to its detrimental effects on emissions equipment (such as catalytic converters) over time.  Unfortunately, it’s the ZDDP that helped to protect the metal-to-metal impact surfaces in engine valve-trains up until the 1990s.  Owners of cars built before then are now experiencing increased camshaft and lifter wear, upsetting a lot of folks who drive classic (and near-classic) cars. …A slight change somewhere results in unforeseen consequences somewhere else…

At this point, if you’re still reading, your eyes have probably glazed over.  Technical minutiae isn’t for everyone.  But sometimes, it’s the tiniest of details that matter.

An EcoBoost Ego Boost

October 13th, 2009 Comments off

If you keep up with what’s happening on the auto-scene, you’ve no doubt heard of Ford‘s EcoBoost effort by now.  EcoBoost is essentially Ford’s moniker for adding forced induction (i.e., turbochargers) to high-compression engines to produce power equivalent to that of a V8 (or a V6) with fuel economy comparable to a V6 (or a 4-cylinder).  Automakers have been doing this for a number of years now, but Ford is making it a core part of their strategy to boost their brands’ fuel economy, spreading the technology through virtually all of their models.

2010 Lincoln MKS

2010 Lincoln MKS

I just finished watching the 6 vs 8 – Showdown at Loveland Pass episode of Speed Test Drive on Speed Channel, in which the Lincoln (Ford’s luxury brand) MKS (with a twin-turbo EcoBoost 3.5L V6 making 355 hp and 350 lb-ft of torque) was pitted against a Mercedes E550 (with a 382 hp 5.5L V8), BMW 550i (360 hp 4.6L V8), Maserati Quattroporte (400 hp, 4.3L V8), and Jaguar XF (385 hp, 5.0L V8).  The challenge was to see if the 6-cylinder Lincoln could keep up with the V8-powered European luxury/performance brands in a 3.7-mile hill climb up Loveland Pass in Colorado, with the finish-line nearly 12,000 feet above sea-level.  Expert rally / hill-climb champion racer Rod Millen was given the honor of piloting each of the vehicles.

The result?  The Lincoln came in second, with a time of 172.7 seconds – a couple of seconds (and about 0.8 mph) slower than the BMW, and several seconds ahead of the Mercedes, Jaguar, and Maserati that came in 3rd, 4th, and 5th respectively.  More striking is the fact that the Lincoln actually reached the highest top-speed on the course (109 mph), demonstrating that it was the handling, not the engine, that caused it to fall just short of the BMW’s pace.

I’ve never driven Loveland Pass.  I have driven over Independence Pass – 100 feet higher than Loveland Pass – and realize what a challenge this test actually is.  I also know how anemic normally-aspirated cars can be at extreme elevations – a fact that certainly played to the boosted Lincoln’s strengths.  And if you’re wondering why the car with the least power appears to be the fastest, note that it’s not the peak horsepower that matters – it’s the area under the torque curve, and the Lincoln’s is wide and flat.

I’m impressed.  That the Lincoln can run with, and even outshine, Europe’s best in any test has got to be an ego-boost for Ford.  But I’m even more impressed with Ford’s efforts to bring the technology to all of their vehicles.  The EcoBoost engine in the new Ford Flex (reviewed here by Autoblog) makes nearly 100 hp more than the normally aspirated V6 Flex, with the same fuel economy.  (I’d like to see them replace that old Duratec V6 with an EcoBoost 4-cylinder.)  The same engine is used in the high-performance Taurus SHO.  And there are even plans to use a version of it in Ford’s light-duty trucks.

I grew up in a Chevy family.  (Growing up the rural south in the ’70s, you were either a Chevy family, a Ford family, or a Chrysler family.)  And though my preferences have shifted to a few German marques, I’ve got to give Ford credit.  While the other American manufacturers have gone through bankruptcy and major reorgs in the last year, Ford has not only managed to survive, but they’ve introduced interesting new technology, all while manufacturing some of the better hybrids on the market.  And that, more than anything, should boost their ego.

ecoboost logo

Rudolf’s Invention

August 20th, 2009 Comments off

In 1892, Rudolf Diesel invented the compression-ignition (i.e., diesel) engine.  The big difference between diesel engines and gasoline engines is that gasoline engines are typically of the spark-ignition type, relying on a spark-plug to ignite the air/fuel mixture, whereas compression-ignition simply relies on physics to cause the air/fuel mixture to ignite when it is compressed to around 5% of its original volume.

VW Jetta TDI Sportwagen

VW Jetta TDI Sportwagen

Diesel engines are significantly more efficient than their gasoline-powered counterparts, and have enjoyed more popularity in most parts of the world.  Unfortunately, the U.S. is not one of those parts.  Although a few manufacturers have offered diesel engines in their light-duty vehicles in the past, about the only mass-market diesel vehicles you can find in the U.S. today are powered by Volkswagen’s TDI technology.  It seems other manufacturers would follow VW’s lead, given the sustained success of the TDI engines.

What’s the problem here?  Maybe it’s marketing: American consumers still remember the horrible diesel engines of a few decades ago, and think of them as noisy, polluting, and slow, when in fact modern diesel engines are quiet, clean, and powerful.  Maybe it’s cost – diesels generally cost a tad more than their gasoline counterparts; however, diesel engines are usually built “tougher” to withstand higher compression ratios, and frequently have greater lifetimes as a result.  And then there’s the efficiency benefits.

…In a past season of Top Gear, the hosts had a contest to see who could drive from Basel, Switzerland, to Blackpool in the UK, driving any car of their choice, but using only one tank of fuel.  Jeremy Clarkson figured it couldn’t be done, so he chose a car that would actually be enjoyable: a Jaguar XJ6 TDVI (diesel) with a fuel economy rating of 35 mpg, and a theoretical range of 655 miles.  James May chose a Subaru Legacy diesel with a rating of 50 mpg, and a theoretical range of 706 miles.  Richard Hammond chose a VW Polo Bluemotion with a 3-cylinder 1.4L engine that gets 74 mpg, but equiped with only a 10-gallon tank.  Before setting off, they properly adjusted their tire pressures, and (in the ultimate display of hypermiling) even sealed the body-seams with tape!

The result?  Richard arrived first, followed by Jeremy, who drove like a bat out of hell with the A/C and all accessories on to demonstrate that it couldn’t be done – proving himself wrong in the process.  …Captain Slow didn’t quite make it.  But, it was an excellent demonstration of the efficiency of diesel vehicles.  Unfortunately, none of these cars are available in the United States.  What will it take to change this?

Internal Combustion

August 7th, 2009 Comments off

Those who know me, and those who read this blog (yes, both of you) know that I am bullish on powertrain electrification.  The truth is, though, that virtually all of the cars on our roads today have internal combustion engines, and it will be that way for quite some time.  Fortunately, the internal combustion engine has come a long way from where it started, and it still has a long way to go.  And although the average fuel economy of vehicles in the U.S. has stagnated over the past couple o’ decades, the engines themselves have become much more efficient, moving around more and more mass at ever greater speeds without an increase in fuel use.

2010 Porsche 911 GT3

2010 Porsche 911 GT3

Recently, I was reading an article in Panorama (the official magazine of PCA) about the 2010 Porsche 911 GT3, whose 3.8 liter engine makes 435 hp.  That’s  114.6 hp/liter!  Not so long ago, the 100 hp/liter barrier was nearly impossible to breach, without using forced induction, but the GT3 blows right through it.  How did Porsche do it?  Well, for one thing, they rev it up to 8400 rpm, and to keep it from disintegrating when it gets there they use forged pistons, titanium rods, and light-weight tappets to actuate the valves.  They use variable valve timing and lift to optimize both the intake and exhaust valves across all regions of the rev range.  They use a variable intake manifold, again to optimize the timing with which the incoming pulses of air reach the backs of the intake valves at various revs.  They use a high compression ratio of 12.0:1.  The whole process is controlled through a sophisticated engine management system which constantly monitors conditions and precisely adjusts any variable related to combustion.

Of course, many of these tricks aren’t confined to high-end sports cars like the GT3.  Many production cars these days using variable valve timing, and variable intake manifolds are becoming mainstream as well.  Another technology with the GT3 eschews, but which auto makers are employing, is direct-injection of the fuel into the combustion chamber, resulting in more control of the combustion process.

Coming down the pike, we see efficiency improvements through technologies like variable compression ratio, such as that demonstrated by MCE-5; GM’s homogeneous charge compression ignition (HCCI), which combines concepts of both spark-ignition and diesel engines; and Fiat’s MultiAir technology, which very precisely controls the valve timing of each cylinder individually.  Combining these efforts with smaller engines using forced induction, such as Ford’s Ecoboost effort, may yield fuel efficiency improvements that go beyond today’s hybrids.  (And the technology compounds – the use of turbos means the ability to use variable turbine geometry!)

Internal combustion engines these days are a far cry from what they were 30+ years ago, when carburetors used low-pressure air to suck fuel out of a hole, and ignition timing was controlled through the centrifugal force of a couple of weights attached to the distributor.  …It will be a long time before we’re all driving pure electric vehicles.  And let’s face it: even PHEVs (and EREVs) have internal combustion engines.  So, let’s hope the advances continue!