Turbo Lag

A turbocharger works (traditionally) by using engine exhaust to spin up a turbine, which in turn compresses intake air, resulting in more thorough combustion and more power.  But this means that at low speeds, there isn't enough exhaust speed to power the turbo.  So when you punch the accelerator, there's a delay before the turbo spins up and the extra compression begins to kick in.  Modern turbochargers are looking to minimize this delay by making the turbines lighter and more responsive, and by using electronically controlled timing to make the process more efficient.  In the meantime, there's turbo lag, which makes Jeremy Clarkson grumpy (not that it takes much, really).

Right on red

The other day, I finally got around to looking up something that I've been wondering about for a while.  The fellow that I carpool with consistently turns right through a red arrow at a certain stoplight on our route, and I had always thought that this was illegal.  So I found copies of some relevant drivers manuals online, and discovered the reason for my consternation.

In Minnesota (where I learned how to drive), a red arrow means that right turns on red are prohibited.  You do not turn until the light turns green.

http://driving-tests.org/minnesota/minnesota-drivers-handbook-online/ , page 61: "A red arrow means “stop.”
You must come to a complete stop at the stopline, before the crosswalk, or before entering the intersection. When the arrow turns green, you may proceed in the direction it indicates."

In Massachusetts, on the other hand, where I currently do most of my driving and where the aforementioned stoplight is located, a red arrow is exactly the same as a red light-- a right turn on red is legal after you've come to a complete stop unless specifically prohibited by signage.  The arrow is basically only there for the opposite situation, when it's ok to turn (green arrow) but not go forward (steady red circle).

http://www.mass.gov/rmv/dmanual/chapter4.pdf, page 81: "A steady red arrow means the same as a steady red, circular signal (see the preceding Steady Red section)."

Key Fobs

The remote key fob for a modern automobile is a pretty cool little device.  It contains a pseudo-random number generator, that synchronizes with your car every time you press the button.  And the system will store 256 additional numbers, so if you press the button when you're out of range, it'll recognize the next number in line, and promptly resynch (if you manage to press the button 300 times in a row when you're out of range, check the owner's manual-- there'll be a way to force a resynchronization).  The fob uses a 40-bit code, which means roughly 1 trillion possible total codes, divided by the 250 that it stores (plus multiple possible fobs per car) gives you still roughly only 1 chance in a billion to accidentally open someone else's car.  This is a vast improvement over the "olden days," when (so I was told) car manufacturers only had a dozen or so basic key shapes.  I myself have accidentally unlocked and gotten into the wrong car (it wouldn't start, and I realized my mistake almost immediately).

Apparently there is a small battery in there, which will run down over time.  The fob can be opened, and there should be instructions inside the cover for replacement.  I was kind of hoping that it ran off of some sort of capacitor instead that charged when you put the key in the ignition, but I guess that wouldn't last long enough if you didn't use your car frequently.

Old transmission, that old transmission...

Today I learned that in an old car (let's say, hypothetically, a 10-year-old Honda Civic with 180,000 miles on it), it's a bad idea to do a complete flush of the transmission fluid.  According to my regular mechanic*, there's enough pressure involved in forcing the fluids out of the transmission that it can potentially do some damage to worn parts that would otherwise be ok.  So, instead, he just drained it and refilled it, a lesser (and cheaper!) process.  Hypothetically.

*I'm still not sure when he became my regular mechanic.  But they started asking me when I call to make the appointment, and I said, "Um, I think his name was... Dave?"  And he called me by name which was honestly a little weird.  Although it's always possible he just looked at the records beforehand, and recognized the car from them.  Sneaky, if so.

Strut Your Stuff

A friend mentioned the other day that her boyfriend's car was suffering from a broken strut (and another on the way out), and I said, "Oh, no, that's awful.  That's a pretty major repair."  And it is-- I mean, I've heard the Car Talk guys mention it in hushed tones a few times.  But then I thought (to myself, so I wouldn't look like a moron), well, I know that a strut is a structural component. It's a support, right?  It resists stress of some sort.  That's what a strut in general is, anyway.  But what exactly is an automotive strut?

To the Internet!  FOR JUSTICE!  Ahem.

One of the most common automotive struts is the MacPherson strut, which really does sound like a dance move of some sort, but oh well.  The MacPherson strut is indeed a supporting structure, but more specifically it's part of the suspension, to wit: those elements of the car that keep it more or less level as it bounces in and out of the inevitable potholes.  I don't want to even think about what the neighborhood around the office is going to look like at the end of the winter, especially since the recent storm probably bankrupted the city.  But I digress.  Again.

The Wikipedia article suffers from a lot of technical language, and seems to be written so that only people who already know the material can follow the text, but I'll try to give some of the high points.

The "main" part of the strut is attached to the center of the wheel and extends upward into a spring, which is connected in turn to the main body of the automobile.  It looks a little bit like the shocks on a mountain bike, for  fairly obvious reasons.  This element evens out the vertical motion of the wheel, making the ride smoother.  But that's only the vertical.  So the strut also has two horizontal components that link the wheel to the steering mechanism and provide additional stability.  This design offers a combination of ease of manufacture and low cost, at the expense of some ride quality and sophistication.

All of which means that my friend's boyfriend's car is probably wallowing around like a whale with a prosthetic leg.