Pulley Size/Fitment: Z34 vs. R35

christian370z

Very similar means they still have slight differences, and slight differences at 7,500rpm become much bigger differences.

__________________
-320whp / 259wftlbs-
SP Rays -- RE-11s -- SpecialtyZ Tune -- Swift Springs -- Stillen 25R Oil Cooler -- Stillen G3 Intakes -- Berk HFCs -- F.I. 12" CBE -- Stillen Sway Bars -- Es14 Spring -- INGS+1 lip -- CF Spoiler -- GTR Start Button -- VLED Parking Lights -- PWJDM V2 shift knob

sloboi

I don't understand theses moot arguments. Are people running around with lightweight pulleys that have NO dampening? Yes. Are there people running their boosted 370Z's with the OEM pulley? Yes. I do not have a sophiscated understanding of the complete mechanics behind torsional vibration; do you? I will assume no. With that being said, my understanding of torsional vibration leads me to believe that dampening this kind of vibration will be fairly straightforward--you take something that will absorbe the energy, like a fluid or a "spring" type solid like rubber, and stick it on the thing you want to dampen. Do you have any logical reason to suggest otherwise? If not, stop posting. I'm not saying I have proof, but most of us understands how vibrations and dampening works, I hope.

There is NO WAY our OEM pulley will have better dampening characteristics than the ATI dampner, even if it's made for a GT-R. Have you seen the little rubber ring? Lol

Please, guys, if you're not here to help with the original question, and are going to attack my reasoning, at least come with facts and logic.

7419sundat

Ill try to help one last time. Every engine has a different frequency that the dampners is designed for. You need to figure out which one your trying. For instance if a race dampners was designed for 10000 rpm it probably wouldn't be good for your car. A daily driver one would obviously dampen at lower frequencies. Basically what if our engines need dampening at 3000 and redline and the dampners you chose didn't do that extreme vibrations could damage your engine especially the more power you have.

sloboi

Which...is the same RPM range as the GT-R...

christian370z

RPMs and the internal balancing from rotational mass, all the internals and so on are two different things. An F1 engine can do 7,000 rpm, just like a Honda Accord or Ferrari 458. They can both hit the same RPMs, but are entirely different engines.

__________________
-320whp / 259wftlbs-
SP Rays -- RE-11s -- SpecialtyZ Tune -- Swift Springs -- Stillen 25R Oil Cooler -- Stillen G3 Intakes -- Berk HFCs -- F.I. 12" CBE -- Stillen Sway Bars -- Es14 Spring -- INGS+1 lip -- CF Spoiler -- GTR Start Button -- VLED Parking Lights -- PWJDM V2 shift knob

sloboi

I apologize if I'm a bit aggressive with my counterpoints. I deal with "factless" arguments a lot, so I get annoyed with them easily.

NOW, with that being said, I admit that my presumptions are rather baseless as well. I am going into this dampening business with two basic premises:

1) That overall, the GT-R and 370Z share a similar engine configuration
-I base this on the apparent similar fitting of the crankshaft pulley, size of shortblock (similar bore, stroke, and intake manifold fitting/size), and of course, an eyeball estimation of width to height ratio of the two engines.
2) That these similarities will mean similar crankshaft vibrations at similar RPM's.
-I base this on...well, nothing. It just makes sense to me that if 1 were true, there is no reason 2 wouldn't be.

Lastly, unless the harmonics of the engine were COMPLETELY off, I still believe that an engineered dampened pulley, at any RPM range within it's designed specifications (which is the same for the 370Z and GT-R), will out dampen the OEM 370Z pulley--which is practically undampened--save the little rubber ring. The added weight of the ATI pulley will also serve to dampen the vibrations by adding additional inertia.

I really don't mind people challenging me, or my ideas. I just don't like it when they make a comment w/o any support. It's like your grade 12 mathematics teacher always said, "show your work."

sloboi

BTW, I've already touched upon this. In reality, the only thing that should affect the harmonic characteristics of the two crankshafts would be the mass of the crankshafts themselves, but considering the breadth of variables considered (which I admit, I lack knowledge on), I've included some other engine specifications/estimations. Besides, if we're considering other variables, wouldn't you assume that a boosted VQ37VHR engine would behave more similarly to a VR38DETT? (I'm not saying the VQ will behave more like a VR than a VQ, just that a boosted VQ will behave more like VR than an NA VQ.)

The engine is already internally balanced, so there should be no "balancing" act needed for the pulley.

christian370z

No one's attacking you, we are offering our view points. But since you seem to have your mind made up, go ahead and do it. Maybe it'll work, maybe it won't. No one's tried it so why don't you be a first?

__________________
-320whp / 259wftlbs-
SP Rays -- RE-11s -- SpecialtyZ Tune -- Swift Springs -- Stillen 25R Oil Cooler -- Stillen G3 Intakes -- Berk HFCs -- F.I. 12" CBE -- Stillen Sway Bars -- Es14 Spring -- INGS+1 lip -- CF Spoiler -- GTR Start Button -- VLED Parking Lights -- PWJDM V2 shift knob