Just wondering something.

As I approach 2000 km on my Z, I've started occasionally going to 5000 rpm and I've noticed that there's no "kick" at 4000 RPM.

On my 2K2 Maxima SE, when the needle sweeps past 4000 rpm, its as if the car suddenly found an extra 30 HP. The acceleration increases suddenly and noticeably, and the engine tone changes. Its enough that on cold days, I will be going WOT in 3rd no problem only to have the front tires break loose at the 4000 rpm mark. According to members of maxima.org, its the variable air intake switching runners.

Just wondering why the Z doesn't have the same surge at 4000 rpm given that the engine basics are the same.

BTW, this car F@#&($* rocks. I drove our 2k2 Max yesterday after a week and a half of driving the Z, what a difference. The steering was so light, as was the clutch. The throws on the shifter felt like shifting a big rig.

 

there is no surge in the dyno curve. so you wouldnt feel one. not sure what the maxima curve looks like, but I wouldnt expect one there either. so Im not sure what it is.

 

I don't know what type of VVT the Max engine has but the Z's is continuous ly variable so there is no step change in timing and there shouldn't be a noticeable bump like what you described. Fluid power delivery is desirable for more control especially in a street car.

That's why I prefer NA to turbo and continuously variable valves and timing to just rpm specific VVT. I've driven some Hondas like the Max that you describe and I was not happy with the Dr. Jekyl/Mr. Hyde approach to variable valve timing.

 

Does the Maxima have linear throttle response like the Z? Maybe that has something to do with it.

 

It's 5K instead of 4K. Regardless of what the dyno plot illustrates with the torque falling off right after 4800, the HP is still rising until 6200. Take it to redline on a nice straight road and you'll definitely notice the difference between 0-5000K and 5000K-6600K.

 

The Z doesn't have variable intake runners. That may be it.

 

That would probably be why, as the kick is supposed to be due to the air intake switching to the shorter runners.

 

From a racers point of view the smoother the powerband the better. The surge of power is fun on the streets but when on the track coming out of a turn, it can cause a highside "opps" ummm understeer is it? Yeah you get the point so lost of traction slower lap times...From one of the magz I read the Z is deceptively fast...interesting coming from a car with a lot of torque...I figure this car is as much or more fun to drive as my Mustang.

I think Nissan had a racer in mind when building this car.

 

I agree with you. I wasn't complaining about the absence of this surge, I was just wondering why it wasn't present given that the engines are supposed to be so similar.

 

same stroke, bore, internals, but different cam profiles, timing, intake manifolds and exhaust manifolds... etc.. So even though the engine is still VQ35DE, it's not quite the same. It's like honda's B18C1 and B18C5, one is the Integra GSR engine with 170 and one is the Type-R engine pumping with 195 horses. They are all B18Cs, but different.

 

Different but the Same...Just like all of us

 

Here check out the new Maxima 4 preview for a lesson on Variable Intake System. Go to explore, energy and enter and underneath Variable Intake System they have a little flash animation to show how it works:

http://www.nissan.ca/en/ms/futuremod...a04/index.html

Basicaly they use a longer intake route at lower rpms to facilitate better gas mileage, after a certain point a valve opens to let air flow through a shorter route as well as the original intake route alowing the engine to get more air volume in a shorter time. That's your kick. The 350 is tuned for maximum airflow (I said maximum but not optimal, aftermarket can still improve) in shortest distance. Sucks for gas mileage but then that's usualy not why you bought the car.

 

Cool. Thanks for the info. I thought I had read/heard somewhere that the longer runners also improved low-end torque. I never understood how a more restrictive/longer air path would improve torque.

The standard intake on the Z looks like a custom intake set-up. I mean, you can see the air filter and it just goes straight back. The intake on my 2k2 Max has alot more twists and turns in it.

 

God, that nose. I'll take the screwed up back end on my 2k2 Max over the screwed up front end on this thing.

 

A lot of you are right about the surge being bad on the track but it is an awesome feeling when it kicks in. I do like that about the Honda engines.