Saturday, August 20th, 2011

Listening to Car Talk on the radio this morning, we heard the story of a guy who stuffed an athletic sock down the intake manifold of his car to avoid dropping anything down there while he was working on it and then, of course, he forgot the sock was in there and put the engine back together. It ran just fine when he started it up, and he even drove it as far as the highway. Either the engine could suck enough air through the sock to run normally, which doesn’t seem likely, or the sock was immediately sucked into the intake manifold when he turned the key, which seems a lot more probable, but it got hung up on a piece of hardware inside that held it back from step two of its inevitable demise.

When he got to the highway, though, the shit hit the fan – or in his case, the sock hit the intake valves when he punched the accelerator and revved the engine up to highway speed. The engine died almost immediately after he stepped on the gas and the guy, wondering why, suddenly remembered the sock. After he steered the car over to the shoulder of the road and stopped, he tried cranking the engine again to see if it even worked, and it ran, but badly, like an engine knocking-on after it had been shut off.

The Car Guys thought that the sock must have been shredded, and that if the guy just started the engine up and ran it, it should burn whatever remained of the sock. There was a lot of discussion about this – the guy though the whole sock might still be down there somewhere, but Click and Clack just laughed and snorted at him and said, No way, buddy, that sock is lint.

The more I thought about it, the more I completely geeked out over this. To get the car up to highway speed, the guy probably revved the engine to at least three thousand rpms – might have been more, but let’s say an even three thousand just for the sake of argument. That’s five hundred revolutions of the drive shaft per second. Each time the drive shaft revolved, all the pistons in the engine went up and down once. Half of them were sucking in air and gasoline, and half of them were blowing out burnt hydrocarbons and water.

The car had a three point eight liter engine. That means the total volume of all the cylinders together was three point eight liters, but only half of them were sucking in air at any given time, so only one point nine liters of air were being drawn in on each rev. With the engine turning at five hundred revs per second, it would have been sucking eighty liters of air through the intake every second. To put it another way: You know how big a two-liter Coke bottle is? Imagine emptying forty of those every freaking second.

When the sock came loose, it fetched up against the intake valves of whichever cylinders were sucking in air at the time. It might have bunched up against the head of just one cylinder, but I’m thinking it probably got torn to pieces by the pounding air pressure whirling around in there and ended up being spread out more or less evenly between all the intake valves. If it was an old-fashioned engine with a carburetor, each cylinder probably had just one intake valve, but if it was a modern fuel-injected engine, there were probably two intake valves per cylinder. More valves doesn’t mean the cylinder gets more air, just that it gets mixed up better because there are more holes around the top of the cylinder for the air to come rushing in.

So, picture it: If there was anything left of that poor, hapless sock by the time it hit the intake valves, forty liters of air per second was whipping it back and forth between the intake valves that were chomping away at it like shark’s teeth. A shark that could suck in air like a jet engine. The intake valves were opening and closing two hundred fifty times a second, every time the cylinder sucked in air. That sock must have been chopped up in the blink of an eye. Literally. If you could have watched, and you blinked at the wrong moment, one moment you would have seen a sock, and the next moment you would have seen a few flying shreds, but probably mostly lint. Lots of lint. That’s why the engine died. It was used to getting forty liters of air a second and suddenly found itself sucking in a big cloud of burning cotton lint.

shredded | 11:57 am CDT
Category: daily drivel, entertainment | Tags:
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