: Below are pages I scanned from a 300zx FSM that I borrowed from a friend. Now it seems that for idle and high speed torque the VTC is off and the duration of the intake/exhaust valves is retarded plus valve overlap is decreased. Once the VTC is activated the duration is advanced and the overlap is increased for better low to meduim speed torque. Here is some other info on the Z32 cams. The cam hieght is 1.5907-1.5982 vs 1.5566-1.5640 of my VG30E cams. The duration of the Z32 cams is 248* compared to 252* of my cams. On the Z32 cams the exhaust valve closes at 9* ATDC vs my 10*, at 59* BBDC the exhaust opens vs my 62* BBDC. The intake valve closes at 69* ABDC vs my 52* ABDC, the intake valve opens at -1* BTDC vs my 20* BTDC. Even though my cams have more duration the Z32 cams' intake opens after mine but they close later than mine. It also appears that my cams have 30* of overlap compared to the 8* of the Z32 cams (hence the bias toward lowend-midrange power). Now onto the clyinder block. It seems that the surface flatness, cylinder bore, Out-of-round, taper, main journal inner diameter, Difference in inner diameter between cylinders are the same measurement as my VG30E block. Now onto the pistons. The piston skirt diameter's are the same, the Z32 piston hieght is 1mm taller than my pistons, the Z32 piston pin hole diameter is 0.9mm larger than mine, the piston clearance to cylinder block is the same for VG30E vs VG30DETT and within tolerances for the VG30DE. As for the valves don't even think about it . The intake/exhaust valves are alot shorter than VG30E valves. The lifters however are 30.9mm outer diameter, 31.0 inner diameter compared to my 15.9mm and 16.0mm. For the crankshaft its specs are the same for VG30DE/TT and VG30E . As are the bearings the same specs too. Also the VG30DE/TT has thicker connecting rods than VG30E. The bearing clearance for the main and connecting rod bearing are the same too. So if anyone has a FSM for a 92-94 maxima use the info I provided in a comparsion for the VE30DE. I would be very interested in knowing the valve timing of the VE vs the VG30DE.

 

Lots of overlap actually is typically a trait of high-rpm cams. Too much overlap can result in lower cylinder pressures at low rpms, hence can reduce torque. The fact that the 300Z has MORE overlap at low- to midrange rpms is due to the fact that they have to do that to get the intake valve to close sooner. Everywhere I've read says that the closing of the intake valve, more than any other cam timing event, determines the torque band of the engine. To close that intake valve sooner for better low rpm performance, overlap must be increased (since the exhaust cam is static), and apparently this results in an overall increase in low end torque in spite of the overlap increase...must hurt emissions, though.

It does strike me that Nissan could have added more overlap on the VG30DE's, though...compare the DE's 18* overlap (VTC activated) to your E's 30* overlap...appears that the DE might do okay with another 12* overlap or so.

Do you know what the VQ's cam specs are? 230* duration on the intake and exhaust cams. Pathetic. Really, really mild. I forget what the overlap is, but it's something ridiculous like only 2* or so...no wonder torque falls off so sharply at 5000 rpm. I wonder if the VG30DE cams would fit? An increase in duration of 18* isn't huge but would probably make a huge impact on the power curve of the VQ. Hmmm...

 

Also the VG30DE has a huge intake manifold runners. They are probably around 1.5 times bigger than mine are, granted this is comparing FSM pics. Next time I goto a dealership I will compare the intake manifold gaskets from the VG30DE, VE30DE and VQ30DE. Or maybe I should just call up Kaleb at courtesy and ask him to do it for me ? hehe