Subject	Not talking about friction
Posted by	PhishZ on December 19, 2004 at 10:11 PM
	This message has been viewed 25 times.
In Reply To	How does mass per valve come into play? posted by SactoTodd on December 19, 2004 at 09:56 PM
Message	think about the actual assembly that actuates the valve. With OHV you have a long pushrod moving a rocker arm which opens a valve. (additionally, you're limited to 2 valves/cylinder with OHV). For multivalve engines with SOHC, some sort of rocker contraption has to be used to operate both sets of valves. With DOHC each valve operating assembly is very simple, and the amount of mass that has to be moved around (within each assembly...overall weight doesn't matter too much, and neither does rotational inertia of added camshafts) to open and close valves is less. At high engine speeds, this results in a lot less momentum (which has to be stopped and started thousands of times per minute) from the reciprocating valvetrain parts, which enables higher revs and greater output. At least thats my understanding as to why DOHC is the valvetrain of choice for high-power engines.
Follow Ups	dual overhead cam? - 300zer 21:24:05 12/19/04 you have 4 = quad (n/m) - Zluster(DFW) 21:25:17 12/19/04 so.. - 300zer 21:30:28 12/19/04 You have a dual DOHC, v6 (n/m) - KaZ (VaBch) 21:42:08 12/19/04 lol (n/m) - BradZ (FL) 21:28:30 12/19/04 DOHC=2 cams above the cylinder - BOOZTD 3 21:29:25 12/19/04 so the prelude is 2 cam and my z is 4 cam? (n/m) - 300zer 21:32:51 12/19/04 you have 2 cams for each side of the V(head) - Zluster(DFW) 21:36:14 12/19/04 yes 2 for each side of the block.. (n/m) - mxsprocket1 21:36:54 12/19/04 lol (n/m) - 90BlkZ18 21:42:55 12/19/04 the preludes 4 cylinders are lined up in one row - BoostLesZ 11:29:53 12/20/04 how is it more efficient? (n/m) - SactoTodd 21:43:12 12/19/04 less reciprocating mass per valve - PhishZ 21:47:53 12/19/04 How does mass per valve come into play? - SactoTodd 21:56:12 12/19/04 Not talking about friction - PhishZ 22:11:41 12/19/04 you even have your own "vtec" (n/m) - Z_animal 22:02:55 12/19/04 what? (n/m) - 300zer 22:17:56 12/19/04 You're both idiots. (n/m) - Tissan© 22:19:20 12/19/04 who? (n/m) - Kurt(Miami) 22:29:09 12/19/04 Z has variable valve timing - PhishZ 22:30:14 12/19/04 He wont understand any of that, but +2 for effort (n/m) - Tissan© 22:34:54 12/19/04 lol (n/m) - PhishZ 22:37:40 12/19/04 Honda's vtec couldn't move the cams until only recently - jkperformance 23:01:07 12/19/04 gotta love it! nice post dude (n/m) - 90BlkZ18 23:04:14 12/19/04 nice info - PhishZ 23:06:54 12/19/04 they really do...i just need to get around to building up - jkperformance 23:14:10 12/19/04 Good post, one thing to note... - BOOZTD 3 23:24:18 12/19/04 or if the engine isn't warm... (n/m) - xZeler8 02:38:29 12/20/04 i knew i'd forget to mention one... oops, thanks though! (n/m) - jkperformance 09:19:30 12/20/04 no problem man! (n/m) - BOOZTD 3 05:47:23 12/21/04 sounds like two ricer boys at it as usual - College Boy 22:24:26 12/19/04 Had a japenese kid tell me that one turbo owns all - Tissan© 22:28:57 12/19/04 nice! haha (n/m) - College Boy 22:43:46 12/19/04 he's a complete ricer i can't stand ricers (n/m) - 300zer 22:41:22 12/19/04 Re: he's a complete ricer i can't stand ricers - 300zer 22:43:26 12/19/04 lol (n/m) - College Boy 22:44:06 12/19/04 find new friends - PhishZ 22:50:27 12/19/04 same here (n/m) - College Boy 23:00:00 12/19/04 not much rice here - 90BlkZ18 23:08:49 12/19/04 domestic guys can be annoying too - PhishZ 23:33:00 12/19/04 Yes. Move along. (n/m) - YugoBernie (NoVA) 23:03:32 12/19/04 yes. + RWD>FWD. (n/m) - BoostLesZ 11:08:21 12/20/04 Re: dual overhead cam? - Z32_ 14:57:26 12/20/04
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