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My car is Chrysler 300C V6 2013 with SOHC So it write 24 valve as you explain have to 12 valves Because you say each Cylender on top only 2 valves it means my car have to 12 valves but actualy 24 valves please more explain to me Many thanks

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    Welcome to the site ... I really don't know what you're trying to ask here. Are you wondering why, if you have a single overhead cam (SOHC) you have 24 valves total in your V6 engine and not 12 valves? Please help us to understand so we can answer your question.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Mar 10, 2017 at 13:40
  • i start a quetion to more clear my order as i explain which type my car so now how many valves have to has ????
    – Akar Jwamer
    Mar 10, 2017 at 13:57
  • Does this answer help you any? It's about the differences between a SOHC and DOHC engines. Really, I'm still not getting what you're after, though I do want to help. I believe there may be a language barrier here, but please don't let that stop you! :o)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Mar 10, 2017 at 14:11
  • A 2013 300C would have a Hemi V8, not a V6. That should have 32 valves, not 24 (8 cylinders x 4 valves). Unless you have the regular 300, then you have a Pentastar V6 which, according to that wiki link, has a DOHC valvetrain.
    – user4896
    Mar 10, 2017 at 17:54

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Each cylinder needs at least 2 valves: one intake valve to draw in the air and fuel mix, and one exhaust valve to release the exhaust gases after combustion.

To make the engine more efficient, sometimes more than 2 valves are used. These days, it's common to have 4 valves per cylinder: 2 intake valves and 2 exhaust valves.
This helps because 2 valves allow more air to be drawn into the cylinder than one, in other words it reduces the air resistance in the intake.

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  • While I agree with you, are you aware there are engines which only have exhaust valves? If you look at the Detroit Diesel -71 series motors, you see what I mean. There may be others.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Mar 10, 2017 at 19:30
  • Sure, two-stroke engines may use ports instead of valves, but automotive two-stroke engines are rare enough that IMO we can ignore them for the purposes of this discussion :)
    – Hobbes
    Mar 10, 2017 at 19:45
  • I was just putting it out there due to the exclusivity of your statement.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Mar 10, 2017 at 20:06
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with a SOHC the single cam per cylinder bank operates both the Intake and Exhaust valves. A DOHC has a cam for Intake valves and another cam for operation of Exhaust valves. Both SOHC and DOHC can have any number of exhaust and intake valves per cylinder - in practice we see 1,2 or 3 intake or exhaust valves per cylinder regardless of the number of cams.

A SOHC engine can still have 4 valves per cylinder as explained above but the phasing between the intake and exhaust timing cannot vary like it can in a VVT DOHC engine.

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  • Is VVT a lot different than VTEC? Because my 1.7 civic SOHC is a vtec which amuses me.
    – method
    Mar 10, 2017 at 23:37
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    VVT uses a mechanism to rotate the camshaft in relation to its drive sprocket. VTEC uses 2 different cam lobes to drive 1 or 2 valves, switching between lobes depending on load or rpm.
    – Hobbes
    Mar 11, 2017 at 8:41

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