Monday, May 28, 2007

My Position has Evolved over Time

Today I went mountain biking with friends. I have decided to start documenting the routes we take. I bought a Garmin Etrex Vista Cx GPS unit along with a handlebar mount. It worked extremely well. Here is our route. The altitude data are flawed for the first .2 miles, but after that the GPS got dialed in. Check it out:

You can zoom to see things more clearly, or click on the altitude profile to see our altitude changes (the Y-axis on this graph is in meters). You can see that we did two ascents to the water tower. The drop at about mile 4.2 is where my buddy Dave went over the handlebars. The "Snow Cave" is at about mile 4.7.

Tuesday, May 08, 2007

Das Auto ist Fast

So today was a red-letter day for me. As shallow as it may seem, I got to live my lifelong dream of driving on the Autobahn in Germany. I drove from Munich to Nuremberg, a distance of around 180 KM (111 miles). This took around an hour. My rental car was yet another diesel with six-speed manual transmission, this time a Ford Mondeo wagon. I will say this until I am blue in the face--why can't the US manufacturers learn from their foreign subsidiaries? This is a really nice car, it is well made, it handles great, and it feels like more like a BMW than a Taurus. Too bad. I guess they tried in the 80's with the Merkur, and that didn't work. So maybe it is more complicated than I think. OK, so here are my observations in list form.

  1. I set a new personal speed record today. I saw a sustained 219 km/h (136 mph) on the speedometer. I know lots of people claim they have gone 160 mph on Interstate 70 or whatever, so this may not seem that impressive to them. But this was cruising along for 20 minute stretches at this speed, and the speedometer needle just would not quite make it to 220 km/h. The few times I had to get on the brakes, the Mondeo hauled it down to 140 or 100 km/h with no drama whatsoever. No shuddering from the brakes. I think most US cars would melt their hubcaps off if you were to try this.
  2. I was flying in formation with a few other cars, including (holy cow) a Volkswagen Caravelle TDI. This is the equivalent of the Eurovan in the US. Dude, all I can say is, wow. This thing is the size of a full-size US van, and it was going 135 mph. It seemed to be more affected by crosswinds than were the cars. Again, wow.
  3. Slowing down to normal speeds after going 135 mph feels like bending time and space. Speeds of 60 or 80 mph feel like walking pace. For getting from city to city, this is a really great alternative to flying in a plane.
  4. I identified two weird behaviors of the rental car, and I spent time hypothesizing about them while I drove. I assume that these behaviors are specific to all diesels, not just to Ford diesels.
    1. The first behavior occurs when the car is "speed shifted." Speed shifting (or at least that's what I am calling it) is when you upshift without taking your foot off of the throttle. You very briefly push in the clutch while very quickly moving up to the next gear. If you do it fast enough, the engine doesn't have a chance to get to spin up to redline while the clutch is in, and the car takes off quickly in the next gear. I tried this a few times because, when accelerating hard, it breaks my heart to waste all of the manifold pressure built up by the turbo when shifting. Anyway, I noticed after performing a full-throttle speed shift that when I arrived at the next gear the car would keep accelerating even if I lifted my foot off of the gas after the gear change. Make sense? For example, I floor the throttle in 5th, and as I approach redline, I briefly push in the clutch and switch into 6th without lifting off the gas. But once I am in 6th, if I lift off the throttle, the car continues to accelarate for a few seconds as though I were still flooring it. This is a bit disconcerting at first, bringing to mind the phrase (verboten in Ingolstadt) "unintended acceleration." My hypothesis is that excess intake manifold pressure, along with unburned fuel, builds up during these speedshifts, and this combination continues to power the car after the shift. As I write this, that sounds wrong, but it's my best explanation. Is this a common issue, known to truckers? Hmm.
    2. The second thing I noticed is that, at normal operating RPM on the highway, say around 2500-3000 RPM, the car produces peak power at 1/4 to 1/3 throttle. I first noticed this when I was cruising on the autobahn. If I applied a slight amount of throttle, the car would accelerate. But if I applied just a little more, the car seemed to produce slightly less power. The diminution in power was so small as to be almost imperceptible. But I think it was real. To test this, I only gave the car 1/3 throttle (the max I could give without feeling the slight loss in power) and the car accelerated smartly up to 210 km/h. So what is the rest of the throttle angle for? My hypothesis on this one is that in a diesel (I think), the air/fuel ratio can vary much more than in a gasoline engine with a throttle. So the perfect stoichiometric ratio only happens by coincidence when you are dumping fuel into the engine with the gas pedal at the rate that happens to match the quantity of air coming into the engine. I wonder if, at 3ooo RPM, that sweet spot just happens to be at 1/3 throttle pedal? If I had one of these cars, I would figure out a way to get an oxygen sensor into the exhaust stream and hook it up to a meter so that I could see what is going on in the engine. Hmmm.
  5. I visited BMW headquarters and got the full tour from a friend. Cool, cool, cool. They are building a massive wind tunnel on the grounds.
  6. Finally, I visited the Adidas headquarters in Herzogenaurach. There is a big factory outlet store there. It is big, but the deals are only so-so. It is worth it to see the cool stuff, but I was expecting to find bargain bins full of odd, special-edition Sambas. There were none of those.