Thoughts on Engine Sound at High RPM's (kinda long)

Red__Zed

I'd actually love to see something from all the people who don't think the engine is rough--what engines are you coming from?

Red__Zed

EK civic or swap?

phelan

...duh?

Are you an aerospace engineer?

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凛 ('Rin') - 2009 Nissan 370Z
With silence comes peace. With peace comes freedom. With freedom comes silence.

Armonster

I came from a 2001 maxima (3.0L version of the VQ) and it was MUCH smoother at higher rpms. Although it only revs to 6000-6500 (cant remember exactly). I have also driven a Cayman S, which is much smoother as well.

Glad I'm not the only one who thinks this engine vibrates like crazy. Kinda freaked me out the first time.

wstar

I came from an LS1 before this car.

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b1adesofcha0s

I came from a 2000 Maxima, but also had a 2010 for a few months.

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tranceformer

VQ35DE

I remember the first few weeks driving it [after breakin] it feeling rough at 5,000+ RPM's. I must have got used to it after a while because it doesn't seem too bad anymore.

I usually have other things running through my mind when I'm approaching redline.

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Ray
2009 370Z Base Sport 6MT / 12.860 @ 109.09mph / 1.921 60ft / street tires
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jtsmith1

No, I work in the aerospace industry and I am a mechanical engineer, haha. I work on a team that designs jet engines, I do mostly mechanical/air flow stuff. Newly graduated though, so Im still wet behing the ears. Worked on airplanes such as the F-16 and the KC-135 for the past 8+ years though.

Zed, I had an EM1 civic. Needed something for college, sold my 240's so I wouldnt keep dumping money into them and got something practical, but it still needed to be a little fun.

My wifes TL also has a v6, although smaller, is much more refined and no vibrations at higher RPM's. That is to be expected with a nicer/luxury style vehicle, but can we learn something from those platforms and apply it to ours?

jtsmith1

A few have spoke of the smoothness of the Porche engines. For a flat six (horizontally opposed), alot of the dynamic forces from one bank are cancelled out by the other. If you think about how the engine operates, this is pretty easy to understand. Unfortunately, that is not the case with our V shaped engine.

Tranceformer, did you notice anything significant when switching over to your JWT flywheel?

phelan

So you're a compressible fluids engineer? Do you use ANSYS for CFD analysis?

And yes, there are multiple reports that a lighter flywheel increases vibration in the crankshaft. That much should be obvious. While it is tempting to consider the easy "oh just make the flywheel" heavier, however, don't forget that a dampener does exactly that - it DAMPENS the response. The full magnitude of the force still must be transmitted, but now it's over a greater time T. So basically...all of the responsiveness of the engine is now thrown out the window.

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凛 ('Rin') - 2009 Nissan 370Z
With silence comes peace. With peace comes freedom. With freedom comes silence.

jtsmith1

Hahaha, nope, still a mechanical (just as I was two post ago). I have not used ANSYS as of yet, but I do see it in my near future (just for my general understanding of the software). My job provides me with resources if I need any CFD done (i.e. a group of people who do nothing but CFD). I more or less use the results to make decisions regarding design. Keep in mind, I am not coming up with any brilliant, new concepts ( at least right now haha), I follow strict design procedure that has been proven with decades of experience and data.

I understand your point about losing engine response, as I think we all do, but some of use who are not tracking our cars may be willing to make a tradeoff, but first we would have to know what that tradeoff is. Minimal performance loss for decent decrease in vibrations, Ill take that all day, because I dont and wont ever track this car.

However, a heavier flywheel may be way out of the question, I dont know the answer, thats why I postulated the question and asked! Wanted to open it up to others who may have more experience and stimulate some outside of the box thinking. This may not even be an option, seeing as the flywheel seems to be fairly heavy to start with. However, if more weight (like less than 10%) could signigicantly decrease the vibrations and sound, I would be a buyer.

Red__Zed

The response you lose with a flywheel heavy enough to do more damping would cause more loss than just not revving that high...

Davey

VQ35DE, VQ35HR, F22C, EJ257.

Again, I don't think the engine is silky smooth, but I also don't see what the hoopla is. It's V6, it is about as good as a V6 is going to get.

crystalline

Coming from an 02 maxima 6mt with the vq35, the new 3.7 feels better. Smoother and faster revving i guess I would say, but it sounds worse. The new engine doesn't sound as good as the 3.5 especially when bolt ons are added.

Nissan370

I know this post is old but when my z was stock it did feel like the motor hated being revved pass 5k
But then I added the supercharger and it sounded like a total different animal up top it sounded much more refined pass 5k
Now that I have the turbo on it that I hate revving pass 5k sound is back

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