Originally Posted by Billman250
(Post 23415168)
Anything over 8400 is really pushing it.
Lower VTEC to 5400, and you have a nice usable 3k rpm powerband just like the Ap1. |
Have you dyno'ed your car? I can essentially guarantee you're not making much power there. Obviously it's your car and you have every right to drive it as you wish, just saying revving an F22 that high isn't productive. :thumbup:
[media]https://www.youtube.com/watch?v=2JNnzqwTUMI[/media] probably been seen to death but it highlights why f22 has a lower rev limit. The technical jibber jabber starts at 2:35'ish |
Originally Posted by Slowcrash_101
(Post 23415088)
It's possible but not advised, at 8400 rpm the f22 pistons have the same speed as f20 at 9,000. So you're pumping the same amount of air, because the bores haven't changed, only the stroke. In fact doing a little math at 9,000 rpm on the f22 crank and pistons, would be the equivalent of 9,670'ish rpm on an f20. The head stopped making power about 800 rpm ago.
:blink: |
Originally Posted by Slowcrash_101
(Post 23416253)
Have you dyno'ed your car? I can essentially guarantee you're not making much power there. Obviously it's your car and you have every right to drive it as you wish, just saying revving an F22 that high isn't productive. :thumbup:
[media]https://www.youtube.com/watch?v=2JNnzqwTUMI[/media] probably been seen to death but it highlights why f22 has a lower rev limit. The technical jibber jabber starts at 2:35'ish |
Originally Posted by yamahaSHO
(Post 23416290)
Originally Posted by Slowcrash_101' timestamp='1416738566' post='23415088
It's possible but not advised, at 8400 rpm the f22 pistons have the same speed as f20 at 9,000. So you're pumping the same amount of air, because the bores haven't changed, only the stroke. In fact doing a little math at 9,000 rpm on the f22 crank and pistons, would be the equivalent of 9,670'ish rpm on an f20. The head stopped making power about 800 rpm ago.
:blink: So given the stroke is longer on the f22 than on an f20, the piston moves faster on the former, than the latter at a given rpm hence power drops off at a lower rpm on the f22 than on the f20 because the head and valves cannot supply enough air past a certain piston speed. Conversely more torque is made at lower rpms on an F22 vs F20 because of higher piston speed at lower rpms displacing more air in the F22 vs F20 because the flow potential of the head has not been exceeded. If I'm wrong please correct me. |
Originally Posted by Slowcrash_101
(Post 23416424)
Originally Posted by yamahaSHO' timestamp='1416846746' post='23416290
[quote name='Slowcrash_101' timestamp='1416738566' post='23415088']
It's possible but not advised, at 8400 rpm the f22 pistons have the same speed as f20 at 9,000. So you're pumping the same amount of air, because the bores haven't changed, only the stroke. In fact doing a little math at 9,000 rpm on the f22 crank and pistons, would be the equivalent of 9,670'ish rpm on an f20. The head stopped making power about 800 rpm ago. :blink: So given the stroke is longer on the f22 than on an f20, the piston moves faster on the former, than the latter at a given rpm hence power drops off at a lower rpm on the f22 than on the f20 because the head and valves cannot supply enough air past a certain piston speed. Conversely more torque is made at lower rpms on an F22 vs F20 because of higher piston speed at lower rpms displacing more air in the F22 vs F20 because the flow potential of the head has not been exceeded. If I'm wrong please correct me. [/quote] The stroke adds to the displacement. The heads and valves are a completely different discussion. |
Originally Posted by yamahaSHO
(Post 23416429)
Originally Posted by Slowcrash_101' timestamp='1416851786' post='23416424
[quote name='yamahaSHO' timestamp='1416846746' post='23416290']
[quote name='Slowcrash_101' timestamp='1416738566' post='23415088'] It's possible but not advised, at 8400 rpm the f22 pistons have the same speed as f20 at 9,000. So you're pumping the same amount of air, because the bores haven't changed, only the stroke. In fact doing a little math at 9,000 rpm on the f22 crank and pistons, would be the equivalent of 9,670'ish rpm on an f20. The head stopped making power about 800 rpm ago. :blink: So given the stroke is longer on the f22 than on an f20, the piston moves faster on the former, than the latter at a given rpm hence power drops off at a lower rpm on the f22 than on the f20 because the head and valves cannot supply enough air past a certain piston speed. Conversely more torque is made at lower rpms on an F22 vs F20 because of higher piston speed at lower rpms displacing more air in the F22 vs F20 because the flow potential of the head has not been exceeded. If I'm wrong please correct me. [/quote] The stroke adds to the displacement. The heads and valves are a completely different discussion. [/quote] Longer stroke increases the volume of the cylinder this is true. It also increases piston speed for a given crank rpm, or is that wrong? As the length of a lever increases, it's motion ratio also increases. The combination of increased cylinder volume, and increased piston speed is what give you more pumping rates for a given rpm vs a shorter stroke. Or is this incorrect? |
Originally Posted by JUSTINTHECOASTIE
(Post 23416300)
Originally Posted by Slowcrash_101' timestamp='1416845527' post='23416253
Have you dyno'ed your car? I can essentially guarantee you're not making much power there. Obviously it's your car and you have every right to drive it as you wish, just saying revving an F22 that high isn't productive. :thumbup:
[media]https://www.youtube.com/watch?v=2JNnzqwTUMI[/media] probably been seen to death but it highlights why f22 has a lower rev limit. The technical jibber jabber starts at 2:35'ish |
Originally Posted by Slowcrash_101
(Post 23416448)
Originally Posted by yamahaSHO' timestamp='1416852235' post='23416429
[quote name='Slowcrash_101' timestamp='1416851786' post='23416424']
[quote name='yamahaSHO' timestamp='1416846746' post='23416290'] [quote name='Slowcrash_101' timestamp='1416738566' post='23415088'] It's possible but not advised, at 8400 rpm the f22 pistons have the same speed as f20 at 9,000. So you're pumping the same amount of air, because the bores haven't changed, only the stroke. In fact doing a little math at 9,000 rpm on the f22 crank and pistons, would be the equivalent of 9,670'ish rpm on an f20. The head stopped making power about 800 rpm ago. :blink: So given the stroke is longer on the f22 than on an f20, the piston moves faster on the former, than the latter at a given rpm hence power drops off at a lower rpm on the f22 than on the f20 because the head and valves cannot supply enough air past a certain piston speed. Conversely more torque is made at lower rpms on an F22 vs F20 because of higher piston speed at lower rpms displacing more air in the F22 vs F20 because the flow potential of the head has not been exceeded. If I'm wrong please correct me. [/quote] The stroke adds to the displacement. The heads and valves are a completely different discussion. [/quote] Longer stroke increases the volume of the cylinder this is true. It also increases piston speed for a given crank rpm, or is that wrong? As the length of a lever increases, it's motion ratio also increases. The combination of increased cylinder volume, and increased piston speed is what give you more pumping rates for a given rpm vs a shorter stroke. Or is this incorrect? [/quote] The longer stroke, by itself, is going to pump more air for a given revolution (and the intake tract will see this). Yes, you'll gain more speed for the same rotation as there is more distance to travel in that revolution, but the fact is you will still be filling more space. Whether or not intake path allows or makes use of it all is another subject. For the most part, you're looking at piston speed from a safety standpoint... Wither it be more wear, overheating, overall vibration from running the motor higher, etc. |
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