BBC HEADS
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EngineTech1
- Expert
- Posts: 652
- Joined: Thu Jun 17, 2004 10:57 pm
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Wow that's a vague question. You can usually get a pretty good idea of what kind of power an engine should be capable of making providing everything else is right but intake port airflow alone isn't the end all in determining power.
What are the specifics of the engine? What kind of heads are they?
Where did you get the flow numbers from? Who dyno'd it?
Be more specific.
Picking up 15 cfm where? Are you talking at only maximum lift on the bench? What were the gains at other lifts?
In general if you figure how much hp per cfm you're making you could use that to rough estimate the gain but it's definitely not guaranteed. You could gain nothing.
It also depends on where you found the extra airflow. I've changed VJ's before and picked up the flow curve, +14 or 15 cfm at my peak test lift which was about .080 more than the engine had running and the engine picked up about 12 hp peak and the average was up about 7.
You could also keep laying the SSR back and see the high lift flow get better and better but you may end up hurting the power at some point. You could also just keep making the port bigger and bigger and it will usually flow more but eventually become lazy on the engine and performance will suffer.
In my experience so far, every time I've picked up airflow in a port I've seen at the least an increase in average power and usually a gain in peak power as well. So far I've never seen a dyno session where the engine lost power after gaining airflow. (Talking about intake ports)
What are the specifics of the engine? What kind of heads are they?
Where did you get the flow numbers from? Who dyno'd it?
Be more specific.
Picking up 15 cfm where? Are you talking at only maximum lift on the bench? What were the gains at other lifts?
In general if you figure how much hp per cfm you're making you could use that to rough estimate the gain but it's definitely not guaranteed. You could gain nothing.
It also depends on where you found the extra airflow. I've changed VJ's before and picked up the flow curve, +14 or 15 cfm at my peak test lift which was about .080 more than the engine had running and the engine picked up about 12 hp peak and the average was up about 7.
You could also keep laying the SSR back and see the high lift flow get better and better but you may end up hurting the power at some point. You could also just keep making the port bigger and bigger and it will usually flow more but eventually become lazy on the engine and performance will suffer.
In my experience so far, every time I've picked up airflow in a port I've seen at the least an increase in average power and usually a gain in peak power as well. So far I've never seen a dyno session where the engine lost power after gaining airflow. (Talking about intake ports)