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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
KWIKXR wrote: I found this little article quite interesting. http://www.pumaracing.co.uk/Exvalve.htm. Has a bit of info on larger exhaust valves etc, even has a table which can be used to kind of give you an idea on what size exhaust valves would suit the CC's of the engine. So if an EF/EL engine is roughly 3984cc, divide that by 6 cylinders gives you say 664cc per cylinder - according to their table at the bottom of the page a sensible exhaust valve size for that engine would be between 40mm and 41.5mm i found the puma site years ago, (it has alot on info on old school ford 4cyl engines) i went through all of there valve size V: engine size V: power potential. and the funny thing is, they were almost %100 spot on. The power you can make through 6 47mm intake valves by their working was almost stop on where %90 of people seemed to be stuck at power wise with falcon engine. (thats why no one seems to ever get much more then 185rwkw on pump fuel.) |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
KWIKXR wrote: I guess the main benefit from going oversize on exhaust valves would be gaining better exhaust flow on the way out. If i can get some larger intake valves maybe 48mm like tickford_6 suggested up above, i may consider it when i get the exhaust valves done. Just a little info, that i thought people might find interesting. The 4L I6 has a cylinder volume of 664cc (x6 total swept volume of 3984.2cc) and uses an intake valve that is 47mm. People seem reluctant to want to go bigger. A 5L windsor ans a cylinder volume of 617.9cc (x8 total swept volume of 4943.1cc) and uses a stock intake valve of 45.21mm. After market heads such as the AFR 185 uses an intake valve of 51.31mm to get flow figures of 277cfm@.600 lift and 267cfm@.500 lift. Edelbrock 61269 heads use a 53.34mm valve and reach flow figures of 309cfm@.600 287cfm@.500 with a 47mm valve NONE of the flow figures i've seen for the I6 have been over 255cfm@.600 most of them reach peak flow @.500 lift. If the ports in the I6 heads can be made to flow 255cfm@.500 on a 47mm valve, I have to ask, what can be done if we squeeze a 48mm or 49mm intake valve in these heads. A 47mm valve has an area of 17.349cm/sq A 48mm valve has an area of 18.096cm/sq (about %4.13 increase from 47mm) A 49mm valve has an area of 18.857cm/sq (about %8 increase from 47mm) I have more to add to this later. |
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