Recent comments in /f/gifs

rathat t1_iwebszh wrote

YES! I’ve said it before on Reddit too, sleep paralysis is also the explanation for alien abduction stories. I have had sleep paralysis myself, and it’s exactly like people describe alien abductions. I know I used aliens coming to earth as an example of something more likely to happen than ghosts, but its second to ghosts lol, I love the idea of aliens, but it’s never really aliens.

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evilleppy87 t1_iwe8c32 wrote

Reply to comment by Snufflepuffster in How an engine works. by ooMEAToo

I'm aware that there's going to be some variability, it just seemed to me that closing 90° before TDC was a little extreme, especially considering in most cases the exhaust valve closes a little after TDC

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Snufflepuffster t1_iwe3wrq wrote

Reply to comment by evilleppy87 in How an engine works. by ooMEAToo

often valves close or open early to take advantage of acoustics (shock waves) to ram air into the cylinder or throw it out. So timing is very nuanced and can be adjusted drastically from engine to engine. In general the exhaust valve isn’t going to match the stroke, it might be early or late, extended or short due to design.

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evilleppy87 t1_iwdssjt wrote

Reply to comment by drsbd in How an engine works. by ooMEAToo

Shouldn't it be open til the piston reaches TDC? If so that means with those cams it should open later in the exhaust stroke. It seems like they start opening just before the piston reaches BDC, and close half way up the exhaust stroke.

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