will valve adjustment affect AFR ?
12-26-2012, 08:27 PM
#11
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I really dont want to hijack this thread . If a cylinder takes in more air than it did before , the map readings will be different than before . Regardless of rpm . Its really not rocket science . I do understand what you are saying . The op has not stated if he is even running forced induction even though this is the forced induction forum .
thank you guys for the great explanation
12-27-2012, 03:28 PM
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@Joes sled: Yes on a naturally aspirated engine map readings will likely change some at wot, but what I am saying is that map does not tell you how much air is getting into the cylinder. Think about it this way...on a turbo car you may be able to build 10psi at 20% throttle, but at 100% throttle you will be filling the cylinder with more air at the same map (10psi)..thus causing the afr to run richer at the lower throttle position if there is no throttle correction applied to the fuel pulse. The same thing in theory can be applied to a valve adjustment. Volumetric efficiency has been altered and you will be flowing different amounts of air at map/rpm points across the board. This will affect idle, part throttle, and wot tuning.
I think we are trying to get at the same thing here, but I am trying to explain why it will now have a different afr at one map/rpm cell compared to before.
I think we are trying to get at the same thing here, but I am trying to explain why it will now have a different afr at one map/rpm cell compared to before.
12-27-2012, 05:27 PM
#13
@Joes sled: Yes on a naturally aspirated engine map readings will likely change some at wot, but what I am saying is that map does not tell you how much air is getting into the cylinder. Think about it this way...on a turbo car you may be able to build 10psi at 20% throttle, but at 100% throttle you will be filling the cylinder with more air at the same map (10psi)..thus causing the afr to run richer at the lower throttle position if there is no throttle correction applied to the fuel pulse. The same thing in theory can be applied to a valve adjustment. Volumetric efficiency has been altered and you will be flowing different amounts of air at map/rpm points across the board. This will affect idle, part throttle, and wot tuning.
I think we are trying to get at the same thing here, but I am trying to explain why it will now have a different afr at one map/rpm cell compared to before.
I think we are trying to get at the same thing here, but I am trying to explain why it will now have a different afr at one map/rpm cell compared to before.
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