Confusing FI question
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,014
Likes: 18
From: Raleigh, NC
Confusing FI question
I ask this question about once a year, and never seem to get any real answers. It's due again, so here we go.
Is boost based on displacement or head flow?
On a 350, do I start to build boost once I move more than 350 cubic inches of air per rotation of the engine, or do I see positive intake pressure prior to that because the restriction is the heads? Which is it, heads or displacement?
Is boost based on displacement or head flow?
On a 350, do I start to build boost once I move more than 350 cubic inches of air per rotation of the engine, or do I see positive intake pressure prior to that because the restriction is the heads? Which is it, heads or displacement?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
OK, the question is what pressure would you see if you ran a blower that emptied into the air not into the engine intake??
Clearly it would take some pressure greater than 1 atmosphere to even pump air in this manner, right. So I think the pressure comes from the fact that pressur must be generated in order to move any fluid. If there is no fluid motion there would still be pressure; pressure would only drop if the blower no longer had the capacity to deliver the VOLUME of air needed.
So a blower must be sized to meet the engine's requirements so that it can deliver the rated pressure in the volume needed by the motor.
Clearly it would take some pressure greater than 1 atmosphere to even pump air in this manner, right. So I think the pressure comes from the fact that pressur must be generated in order to move any fluid. If there is no fluid motion there would still be pressure; pressure would only drop if the blower no longer had the capacity to deliver the VOLUME of air needed.
So a blower must be sized to meet the engine's requirements so that it can deliver the rated pressure in the volume needed by the motor.
