 OT: 4 Valve Vs. 2 Valve, What's The Advantage? |
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| windforfun |
 Feb 11 2024, 11:48 AM
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#1
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Senior Member  Group: Members Posts: 1,823 Joined: 17-December 07 From: Blackhawk, CA Member No.: 8,476 Region Association: None  |
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| Rufus |
Feb 11 2024, 11:59 AM
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#2
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Member Group: Members Posts: 314 Joined: 8-April 06 From: Central NC Member No.: 5,840 Region Association: None 
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4v - allows optimized plug location which allows higher compression ratio,
allows greater valve area for better breathing / volumetric efficiency, reduces valve train mass for each valve spring to control, which raises valve train rpm limit |
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| technicalninja |
Feb 11 2024, 12:01 PM
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#3
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Senior Member Group: Members Posts: 1,300 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region
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25-40% more airflow.
Almost always cross flow. Less "curtain" regarding valves Automatically makes it hemispherical (or semi-hemi) Valves are significantly lighter allowing for less valve spring tension which reduces frictional losses. Higher engine speed because of this. Total cam drive load can drop more than 50%. Less stress on camshaft drive equipment. Forces center chamber plug location (single plug heads) Reduces "burn time" allowing less timing to reach MBT. Normally smaller valve stem diameter and less side loading on valve. Reduces guide wear. Only downside that I can see is added complexity. This can make shim style valve adjustments a PIA. Many Toyota V8 have 32 valves to adjust! |
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| brant |
Feb 11 2024, 12:31 PM
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#4
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914 Wizard Group: Members Posts: 11,632 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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Incoming charge increase
Easier exhaust scavenging Turbos also force more air in But more valves reduce NA restrictions for intake |
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| 930cabman |
Feb 11 2024, 05:47 PM
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#5
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Advanced Member Group: Members Posts: 3,130 Joined: 12-November 20 From: Buffalo Member No.: 24,877 Region Association: North East States
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More air in and more air out = more power
Check out the Ferrari 355 developed in the mid 90's. 5 valves/cylinder |
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