VH41DE and VH45DE Camshaft Angles

Discuss topics related to the VH41DE, VH45DE, VK45DE, and VK56DE engines.
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Ezekial
Posts: 355
Joined: Sun Nov 28, 2004 4:42 pm
Car: 2001 Nissan 200SX S15

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Anyone know the Inlet opening and closing and Exhaust opening and closing angles for VH41DE and VH45DE engines?


Q45tech
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Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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The 90-95 Q45 uses an intake cam of 248 with 0 or 20 BTDC [vvt] so it closes at 112 or 92.

The exhaust is also 248 and closes at 8 ATDC so opens at 120 ATDC.

Don't have a 4.1 FSM on hand but remember~~ 236 degrees duration.

Modern OBD2 engines [Q41 etc] use less duration and much less overlap.

Not necessary with big multiple valves, as the SUM of the opening flow is what counts.......the curtain area = ratio of imaginary cylinder [valve diameter less seat , less valve stem, times lift. The problem with big valves is like big cams at idle.

Extra Lift is the usual variable added to performance cams [for 32v engines]vs. duration........but tiny margins in valve to pistion clearances when extremely hot, thus flycuts in pistons.

The exhaust cam durations on both engines could be increased to gain 5-10% at the expense of idle........as the vvt engine idles with a only 8 degrees overlap vs 1500-4500 at 28 degrees and back to 8 above 4500....another 10-15 degrees might open it up to above 6200 rpm performance.


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