I have had my Z for about a month now, and I followed the babying it philosphy for the first 600 miles. I have now begun to rev it a little more up to 3500 to 4000 rpm (I was previously shifting at 3000 rpm). I found the engine very smooth up to 3000 rpm. However as I now begin to explore the 3500 to 4000 rpm range I find it lacks the slick flowing character that I've experienced in my Z32, BMW inline sixes and other world class 6 cylinder engines. Its noise and overall quality is not as smooth as I expected. I remember reading an early reviewof the 350Z that referred to the engine as a "truck" engine and had a similar comment about its harsh quality in the upper ranges. Do others feel that the engine is as smooth as the Z32 engine or the BMW inline 3.0? Is perhaps the roughness I am experiencing a characteristic of the "green" nature of the engine?

 

Mine's still as rough past 5000ish RPM at 3000 miles as it was after breakin. I think it's just the nature of the engine.

 

I used to drive the 3.5 Maxima and seemed smoother because it was so much quieter. Unlike the 350Z, the intake is so much open which makes it much louder. Its a sports car suppose to be loud. which I like. The 3.5 VQ is a high tech engine. The magazine reviews gave a perfect 10 and 9.

 

The inline 6 configuration is inherently less of a vibrator than any V6, including your Z32 and the Z33. Punching out the VQ engine by .5 liter may have added some vibration, but it seems to me to me more noise than vibration. Maybe I'm just not perceiving it correctly, but the Z33's vibration doesn't seem to be very bad at all. When you pass the torque peak(4800), the noise increases and a little vibration sneaks in after 6000rpm, but nothing objectional. I have found it to be less noticable as the miles mount up, but that could be me getting used to the coarseness of the sound, not a vibration. I've hit the rev limiter a couple of times because the sound just seems the same after 5000, just a little louder.

The engine does have 1 or 2 balance shafts on each bank, but big V6's will never have the smoothness of a straight 6 or a V12, both engines are inherently better balanced than any other engine except the flat 6s of Porsche or Subaru, yes, a subie's flat 4 engine is almost as well balanced as their flat 6 they had on the SVX of the early 90's. I think the 3.5 V6's sound at high revs is contributing to your perception of vibration, it is rather coarse, but I don't feel much vibration at all.

 

Have you been in a Z with a grounding kit? If not, take a ride in one to see if you feel an improvement above 4000rpm

 

thanks for the comments, I think Boomer is right in that my perception of roughness or harshness relates to the sound of the engine...it doesn't sound like it wants to be revved whereas my Z32 did...indeed the 2.5 liter V6 in an Mx6 I owned had a smoother more polished quality than the Z33 engine does in my opinion...I suppose it is a trade off in the end for the torque and instant response provided by the large displacement....

 

Thats pretty much the way I look at it.

 

Comparing the 3.5 in both my Max and 350 to my old 3.0 VQ in my 01 they are a tad rougher around the edges, neither is as smooth at idle or at high rpm as the old 3.0 VQ was. Several publications have noticed as well that the 3.5 isnt as smooth as the old 3.0 VQ.

 

I agree. Above 4000 rpm, the perceived roughness is lessened significantly. Still not as Honda smooth, but improved.

 

Well maybe I'll have to try that grounding kit. The engine sorta sounds like I'm about to disintigrate it above 5k right now, which I've just sort of re-baselined my comfort level for. I also remember my 95 Maxima, which I traded in for my Z, not sounding so rough at higher RPM. Right now its still kind of a "Yikes! Am I about to break something?" kind of feeling.

 

Hmmm, it's funny how perceptions can be so different. In some ways I feel similarly to the rest of you, but in others I feel differently.

I definitely notice a roughness, not due to RPM, but rather due to throttle. If I am loafing along at 80 or faster, then engine seems very smooth even though it may be at 3K RPM or above. However, when I jump on the throttle, I definitely notice vibration; enough to cause rattles on the dashboard and shifter.

The engine sound, though, does not bother me at all. The intake and exhaust are evident, but I don't notice a thrashy feel, or a significant difference in sound as I get to the upper RPM ranges. I've even hit the rev limiter on occasion because I never realized I was approaching the redline.

Anyhow, I'd say that the engine isn't very smooth or quiet, but that doesn't bother me since in a sports car I'm not looking for smooth or quiet. I want a car that's exciting, visceral, and gets the adrenaline pumping. I therefore like the feel of the Z. It lets me know there's really something under the hood.

-D'oh!

 

there is a noticeable difference to 'engine smoothness' between my Z and my friends g35 - im guessing they did so on purpose...

 

I agree with boomer, engine sound is directly related to preceived engine harshness and vibration. My 97 maxima with the 3.0 VQ was VERY smooth and very quiet throughout the entire RPM range...until I started modding it. With intake and full exhaust the engine did develop a bit of harshness and perceived vibration due mostly to the increase in sound from the modifications.

 

My engine has smoothed out SIGNIFICANTLY over the past 10000 miles running Nissan recomended (non-synthetic) oil.

The engine harshness at high RPMs really bugged me for a while, but now its MUCH better.

 

I have no other alternative but to believe this is how Nissan wanted it. Give it a little "soul" say. My Z engine feels like a rock tumbler compared to my 3.2 V6 in my Acura TL. I think Nissan really wanted you to feel the beast within !

 

Stiffer engine mounts probably have most to do with you being able to feel the engine more....

 

I think this is exactly right. Not another vanilla Honda engine: reliable as hell but about as memorable as a night on the town with your sister.

Anecdotal evidence is the "rough" vibration in the shifter. Nissan left it in to give better feel for what the car is doing. Honda and Toyota (and even Nissan on an Altima or I35) would have taken that vibration out, making it "smoother" but also less connected with the driver.

I honestly never thought of this engine as "un-smooth". It sounds syrupy smooth to me. Loud melodious syrupy smooth. :-) Unsmooth would be the Chevette I used to drive in high school. Or the engine in my girlfriend's CRV that always sounds like it's reluctantly over-worked ("just leave me alone... I don't want to go that fast!"), buzzing noticeably at higher RPMs.

 

Nope the Vibration is in the 3.5 Max (manual) and G35(manual) as well, its just like the 350's idle not so smooth and above 4000 it gets a little rough feeling as well!

 

My Harleys vibrate a lot, the girls love it.

JMS in TX