Torque Wrench Tech, Diesel vs. Gas, Parking Lights, Bumper Stumper, and Deep Stuff - Franz Kafka's Garage

Send questions to “Franz Kafka’s Garage,”1585 Eisenhower Place,Ann Arbor,MI48108ore-mailFKG@CARandDRIVER.com.

SHERLOCK KAFKA

Maybe you can explain how a “master technician” can be pulling on a torque wrench with his left hand while he “assembles a GT-R engine” [Nissan ad, page 37, November 2008]. Wouldn’t that motion be loosening the fastener? Maybe the secret to big power ultimately developed is left-hand threads? Or is it that you need to push on the wrench?

Jim BenedictStamford, Connecticut

Because the ad uses a photograph and is not one of those Japanese comic books that Kafka frequently reads, there are no streaking lines to indicate motion. Thus it’s not clear if the technician is pushing or pulling on the wrench. Look closer, though, and it’s likely that the guy is doing neither. The tool being used has a large cable attached to it, which means it’s probably electric or air powered and can deliver a precise amount of torque to a fastener with a simple push of a button.

DIESEL VS. GAS

If a diesel [engine] can burn most anything, then why can’t it burn gasoline?

Lew CampbellSanta Barbara, California

Discussing the differences between gasoline and diesel fuel can be fairly complex, so Kafka will try to keep it simple. Basically, gasoline is made to resist knock, which is what happens when air and fuel autoignite (spontaneously combust) before the spark plug lights them off. Diesel fuel, on the other hand, is made specifically to ignite in this manner from compression as a diesel engine doesn’t use a spark plug to initiate the burning of fuel. In a gasoline engine, the air and fuel are evenly mixed in the chamber, and combustion starts at the spark plug and emanates outward. In a diesel engine, the combustion starts at the edges of the cylinder where the ratio of vaporized fuel-and-air mixture is ripe for autoignition and progresses depending on how quickly the rest of the fuel diffuses. As the diesel fuel will start burning very quickly, it’s injected into the cylinder later than it would be in a gasoline engine. Two things would happen if you tried to run gasoline in a diesel engine. First, gasoline’s resistance to compression ignition would delay combustion, messing with the timing in the cylinder. Also, gasoline burns faster and at a higher temperature, which would increase noise and pressure in the cylinder, assuming the engine and the injectors could handle the extra pressure and heat.

PARKING LIGHTS

Do you know when parking lights were first used? What was their original purpose?

Bob BartoltCincinnati, Ohio

No.

BUMPER STUMPER

Not long ago, we were going to 5-mph bumpers. Now most cars have bumpers that sustain damage at just about any contact. What happened?

John F. PhelpsVail, Colorado

The National Highway Traffic Safety Administration (NHTSA) first established a bumper standard that automakers had to meet for the 1973 model year. It required that safety components such as headlamps and the fuel system remain undamaged after a 5-mph front impact or a 2.5-mph rear impact. The standard got tougher for the 1979 model year, prohibiting damage to all exterior vehicle surfaces except for the bumper. By the 1980 to 1982 model years, the law required that a car sustain no damage to the body and very little damage to the bumper itself. For 1983 and later cars, the standard was relaxed to the current 2.5-mph standard. Why? The legislation that established the bumper standard specified that the new rule should offer the maximum cost benefit to the consumer, taking into account insurance, repair, and the cost to implement the stronger bumpers in the first place. Studies showed that reducing the standard to 2.5 mph would incur slightly more in repair fees, but that the bumpers themselves would cost less. The standard only applies to passenger cars; SUVs, minivans, and trucks are exempt.

DEEP STUFF

When reading Franz Kafka’s Garage, one can reason that since “Franz” is a singular noun, one is speaking to a person. But sometimes Franz drifts off into the plural “we.” Is he delusional? Perhaps it should be Franz Kafkas’ garage, as it appears there is often more than one Franz responding.

Keep Reading: Torque Wrench Tech, Diesel vs. Gas, Parking Lights, Bumper Stumper, and Deep Stuff - Franz Kafka's Garage