Neat write up on PI vs NPI vs SVO

97vertstang

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nPI Heads:



Combustion chamber volume: 51cc *

Intake port volume: 146cc

Intake valve diameter: 44.5mm

Exhaust valve diameter: 34mm

Intake flow @ .500 lift: 156cfm

Exhaust flow @ .500 lift: 116cfm

nPI Cams: .480 lift (duration at .500 = 204 intake, 208 exhaust)

* Initial 4.6L engines utilized flat top pistons.



PI Heads:



Combustion chamber volume: 42cc **

Intake port volume: 159cc

Intake valve diameter: 44.5mm

Exhaust valve diameter: 36mm

Intake flow @ .500 lift: 156cfm

Exhaust flow @ .500 lift: 133cfm

PI Cams: .535 intake, .505 exhaust (duration: 192 intake, 184 exhaust)

** PI equipped engines utilized dish pistons to keep the compression ratio at 9.7-1.




in there it says that npi cams have more duration and less lift. the pi cams have more lift but less duration. so modular engines like more lift than duration :dunno: or is that a typo??? i would think duration would give more power than lift??? at least on most other engines thats the way it works.
 
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