I love my 350 in many ways including its stiff structure that inspires confidence, its eager and composed feel, its clutch and shifter action, its beauty, its functional interior and of course the incredible torque its engine generates. But what I don't like is the NVH (noise vibration harshness) that this beast of a motor generates. I actually find its quality irritating to the point where it discourages me from revving it. It is not a polished buttery turbine smooth powerplant. I owned a Z32 and used to LOVE to rev it. I also owned a Mazda Mx6 with the 2.5 v6 and LOVED to rev it. I have driven BMW inline sixes and loved the way they revved and sounded. The 3.5 in the Z just can't compare, it sounds unrefined, thrashy, "truck like" and as I said almost irritating. The engine is I believe the most important part of a car, the part that most influences one's affection for the car. The 3.5 has really started to wear on me and affect my love of the car.

Is there anything that can be done to change the quality of the engine to make it more polished and turbine smooth? Change the intake? Add aftermarket soundproofing? Anyone tried anything that works?

 

You're going to get suggestions to get one of those grounding kits. Personally, this Mechanical Engineer and track instructor doesn't believe in them, but it's up to you.

Jason

 

the Z's engine is designed to be smooth; but your right, it is a bit rough.

I think it stems from 2 things; first and foremost, 3.5L is pushing the envelope on how big a V6 should be. GM has a 3.8L that is the largest I beleive. I think all that mass causes small imperfections in balance to become a bit more noticable.

and second. it is rather powerful, its no secret the engine is not a refined supercar engine. it is a workhorse of the nissan line. and is mass produced probably more than any other engine. supreme smoothness isnt gonna be too easy.

but all in all, I dont think it detracts from the experience, if anything it adds to it. smooth is nice, but sometime raw force is nice too.

 

Well, youre never gonna get that buttery smooth sound/feel of the BMW, but it WILL smooth out with age. Mine was way to harsh to begin with, but after 5000 miles or so, it began to break in. Also, Im gonna install some Dynamat Extreme (a cheaper alternative actually) to the firewall and rear of the hood to help quell some of the NVH so you can focus on the nice exhaust note more.

 

Nah, My S-10 has a 4.3 V6

 

The grounding kits does help, its hard to beleive but unless you try it you will never know. As a cheap test, connect some jumper cables from the intake manifold to somewhere on the chasis and start the car. Take them off and on and see if you can feel a difference.

 

Yeah i was gonna say...checy has a 4.3 V6 and Ford has 4.0 V6. 3.5 is not pushing the envelope by any means especially with DOHC and 24 Valves. It does seem this engine would be smoother considering it has all that plus CVVT.

 

I guess it's just this old geezer's background in old musclecar solid-lifter V-8s, but the 3.5L has actually impressed me with its smoothness...but I'm not what you'd call a BMW person...

 

part of the problem is the VQ was originally an extremely smooth 3.0 in its maxima days. Then they bored it to 3.5, made some minor internal changes and called it the VQ35DE. The block is still the same size as in its 3.0 days so there is less mass to dissipate sound and vibration now.

several magazines have noticed this. If you want it to rev faster, install a Underdrive pulley set and maybe a crank pulley. Then if you want it to rev even faster intall a lightened flywheel. Do these things and it will rev awesomely. Now an intake will also help but it will make it VERY loud at high rpms.

A grounding kit will make it start and idle much smoother and a larger exhaust (even jsut a catback) will give it a little lope at idle but will be loud at 2000-3000 rpms

No V6 can touch an inline 6 (BMW, Porche, Jeep) for smoothness by design

 

mine too!

 

Yup, tis true. Straight sixes (and V12s, I thikn V8s, and osme others) are inherently balanced due to their design, but V-6s require conterbalances to smoothen some of the vibration, but they also sap some power. I would bet that they are smaller on the 350 than on some of the other 3.5 applications to sap a little less power, but that is just an assumption. But, it seems smoother in the FX35 and the altimas I've been in, but that's probably for a number of factors besides the engine.

Now, the 4.3L in my blazer was THRASHY, and was more bark than bite. The 3.5 doesn't bother me any in a sports car.

 

correct me if i am wrong, but isn't BMW moving toward a V6 in it's next generation of 6 cylinder engine? (as it's current M50,M52..and so on revisions of the I6 engine nears its production life span.)

 

Post -
Of course there's always getting your engine blueprinted. Bring $$$.

Inline 6 in a porsche? All I know is flat 6's.

N8vz-
I've read BMW will go to a 4.0 V8 with 400hp for the next M3 and M4.

 

thanks for the input, I am relieved to find that my perception of the 3.5's roughness is not unique to me. Thanks for the suggestions re soundproofing and mods to enhance the rev ability of the engine. I think I will try the firewall and hood soundproofing first to attempt to quell the NVH that the 3.5 beast spews forth. Hopefully then I will be able to focus on the undeniably addictive pull of the torque and the sweet exhaust note!

 

hmm..for some i think its a positive thing...

 

inline 6 is inherently balanced, as well as V12(2 inline 6's) I dont beleive any other engines can claim it(other than V18, V24 ect. the pistons going up and down all perfectly counteract each other.

 

I agree with post350Z about the NVH qualities. What's interesting is that my 02 Maxima (same engine, totally different intake and exhaust setup and only 255 hp), feels WAY smoother and quieter.

It basically feels like the Maxima doesn't have to work as hard to accelerate. Try an 02 or 03 Maxima out to see what I mean. I haven't had a chance to take my Z out to the track yet for drag racing, but I'm sure that it'll be significantly quicker than my Max in the 1/4 mile.

I guess the Z has a LOT less sound insulation and maybe the transmission placement has something to do with it. The exhaust note on the Z is WAY better though.

 

the 3.5 in my G35 is a lot smoother as well. Always wondered why but didnt bother me too much.

 

i love the rough engine sound, dat scared the **** out of all those civics and celicas, my fairlady is a beast.

 

could try this:http://cgi.ebay.com/ebaymotors/ws/eB...tem=2446927141

dunno if it works tho