I thought our engine did make decent power between 6400 and about 6800...but the rev limiter really gets in the way...so by removing it, you're able to use all the power all the way to 6800...sure you're not getting to 7000, but is 200rpms worth it?

I dunno...I think the new engine sounds great, but I think a couple of simple mods to our current engine and we're right there.

Except for the stronger rods?

 

Nope.

Look at the torque curve. Then look at the HP curve.

The torque curve falls early, but really starts dropping around 6400 RPM. It's dropped below 90% of peak after around 6000 RPM.

RPM is able to make up for the torque loss and keep HP fairly high until the peak around 6400 RPM, but HP falls off after that. Raising the fuel cutoff to 7200 RPM doesn't get you anything. HP falls off rapidly, so you're not making more power. You might as well just upshift and get the engine back into the powerband.

In a high performance engine, you ideally want a flat torque curve, and a linear HP curve with peak HP at or near fuel cutoff. See an F20C dyno as an example. The Z has a pretty flat torque curve, which is great, and it has lots of torque down low, which is a bonus (nice daily drivability).. but the stock cam duration really takes the breath out of the engine at upper RPM. The other engine characteristics (bore, stroke, rod length) all point to a peaky high-revving performance engine, but the cam and flywheel say otherwise.

I think that a cam with more duration, the upgraded VTC sprocket (55 degrees of phase variation, versus 40* stock), and upgraded VTC and air/fuel maps would really yield some serious upper end power out of this engine with minimal loss of torque down low. The greater cam phase modulation with the upgrated VTC sprocket would allow the ECU to eliminate overlap down low, while opening it up near the upper RPM range to facilitate high-RPM breathing. Best of all worlds.

 

I intend to do some datalogging on the VTC solenoid control signals vs. RPM and TPS so I can understand the control better. In the future, I intend to run a full standalone ECU, so I might try and whip up some custom electronics to control VTC with my own custom map(s). Not sure when I'll get around to it, but if it's successful, then I will most definitely try to incorporate the upgraded VTC system into my engine. If donations were involved, I might be able to move up the timetable on my research. I'm somewhat hampered by my limited income..

Does anyone know where I can find out more technical information on the operation of Nissan's C-VTC (sometimes called CVTCS) system? Or even the older VTC (From the VG30, VQ30) ? I've been searching the US patent office for information they might have in their patents, and I've had very limited success.

Matt

 

azrael- there was a bunch of info posted here not long ago....try looking back in this forum about 2 weeks ago for a thread with the NISMO cam gears in the topic

 

Bolt-on's will yield those numbers and definately lots more tq.

I find myself wondering what gains are to be had if I added cams to my car. In my Z's present "state of mod", my car would do quite nicely with them.

The engine in the anniversary Z is nice but IMHO not worth all that hype about the bumped hp. I'm very happy with my engine I love to really drive it.

 

As has been mentioned, it is the Nismo S1 engine. Road and Track ( I think it was them) has tested the prototype a few months back. Higher hp, lower torque....No change in 0-60. 0.1sec faster in 1/4 mile. Purely an advertising thing in my opinion....just so they can say "300".

 

I'm constantly checking nissannews.com and nissanusa.com for new info. I found out that only the 35th anniversary edition and the track model will receive the hp increase, the rest of the lineup will not.

I look forward to some testing results out of the newer cars. It should be interesting to see the differences. It would seem to me that a loss of torque would be a detriment. However, if it’s only a loss at higher RPM that wouldn’t be so bad as long as the low-end torque remained.

I feel that the low-end torque and well designed chassis is responsible for the incredible performance. I still tout the article in the March 2003 Road & Track “David and the Goliaths.” It’s a must read if you haven’t read it before. It puts the 350Z up against a Z06, M3 SMG II and a 911 Targa. The moral of the story was that the 350Z lost almost every category in performance compared to the others, however came in second only to the Z06 in lap times at Willow Springs International Raceway, proving that the 350Z has what it takes to be a winner, even on a low budget. The 350Z had less hp than all of the rest but had more torque than the rest except the Z06. The Z06 was the winner but at a much higher cost $51,450.00.