70_Nitrous_Eater said:From the dyno sheets I've seen:
If you are already using a high lift (performance) cam, you won't see much benifit (maybe 5 hp).
If you are using a lower lift cam (stock grind) then there will be a large increase in power (Up to 20 hp in a stock 5.0)
D.Hearne said:I think, 70Nitrous eater's observation may have been in error, the gains with a stock cam shouldn't be any more different than with a bigger cam, the specs he saw may have been due more to a change in rocker type ( stock to roller)
70_Nitrous_Eater said:Nope.. Think of it this way: After you open the valve a certain distance, there will become a point where opening the valve any further won't make much of a differancein airflow. With a high lift cam and 1.6:1 rockers you are already getting to that point..stepping up to the 1.7:1 rockers gives more lift but this extra lift doesn't make much of a difference anyway. But with a stock lower lift grind, the added lift of the 1.7:1 rockers makes for a larger increase in hp.
An analogy: You take a V8 that's built for a 650cfm carb and you replace the carb. Stepping up to the 750cfm might gain you a few extra hp, but stepping up to a 900cfm carb wouldn't make any more power that the 750cfm.
Ditto, couldn't have said it better69Rcode_Mach1 said:Well that is true, but it takes a lot to reach that point. That has to correlate with the compression and total lift on the cam. Usually when the lift is too much you will be close to .600 lift depending on the engine. I wonder how that stock cam would respond what you are saying makes sense to me, but it doesn't seem that the stock cam is so terrible that the .032" of lift would make that big of a difference.
I see what you're saying here, but I think that would happen only in rare cases with the switch in ratio.70_Nitrous_Eater said:Nope.. Think of it this way: After you open the valve a certain distance, there will become a point where opening the valve any further won't make much of a differancein airflow. With a high lift cam and 1.6:1 rockers you are already getting to that point..stepping up to the 1.7:1 rockers gives more lift but this extra lift doesn't make much of a difference anyway. But with a stock lower lift grind, the added lift of the 1.7:1 rockers makes for a larger increase in hp.
An analogy: You take a V8 that's built for a 650cfm carb and you replace the carb. Stepping up to the 750cfm might gain you a few extra hp, but stepping up to a 900cfm carb wouldn't make any more power that the 750cfm.
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