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Not underdriven but not harmonically dampened. Is our stock pulley even dampened? Will this one create unwanted engine vibrations leading to a shorter engine life?
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The technical answer is yes, the real-world answer is MAYBE.

At stock power and rpm it's going to be minimal on both the DE and HR engines, there's a pretty massive history of people using lightweight pulleys on these engines without any catastrophic failures like the problem SOME engines have when you remove the damper and put on a lightweight aluminum crank pulley.

B series Hondas had lots of issues, mostly due to the crankshaft flexing, K series did not because of the much better internal balancing and torsional stiffness of the crankshaft, the DE and HR engines are in this latter category as well, the crankshafts are SO overbuilt that they don't have nearly the flex so vibrations are very very minimal at STOCK power levels.

The stock DE and HR crankshafts can handle well over 1000whp, the added mass just inherently limits the amount of vibration/harmonics which is why the stock crank pulley is nearly all metal and very skeletonized and only has minimal damping (there is an elastomer ring but it's pretty tiny). Add on a torque converter bolted to the end of the crank and you have a massive fluid reservoir that also damps harmonics, on the stock 6MT there's a massive 30lb chunk of flywheel that absorbs harmonics somewhat. It doesn't entirely eliminate it but when you spread the same vibration over a larger mass of metal the frequency isn't nearly as destructive as it would be on a smaller mass of metal.

If you have a 6MT and are running a lightweight flywheel then I would recommend the stock crank pulley, if you are 6MT on the stock dual mass flywheel OR if you have a 5AT then you're probably fine with a lightweight pulley.

If you're FBO including cams then you should probably not be running a lightweight crank pulley, stock pulley is fine though.

Intake+exhaust+tune you're probably fine though.

If you are raising the redline AT ALL I would recommend the stock pulley, you can kill oil pumps with harmonics.

If you're any kind of forced induction then you DEFINITELY don't want a lightweight pulley and anything past like 450whp you should start to look seriously at a BETTER damper pulley since you're creating more crankshaft flex and thus more potential harmonics.

Hope that helps a little, there's very little actual data on the subject of VQ harmonics and it's almost entirely just the collective 20+ years of experience people have had blowing up / wearing out 350Z and G35 engines. You can't exactly compare it across other engines because there's so many little things about the design of the engine that significantly affects how/when those engines start to have trouble due to harmonics.

Generally speaking though, engines with external balancers are worse than internally balanced engines and inline engines are better than V block engines.

 

Great, extensive knowledgeable info as usual. Gracias Senor. I'm FBO with tune, no cams, but raised redline due to UpRev so......no lightened crank pulley in my future. #SaveTheOilPumps

 

Well let me rephrase that since the base DE engine only has a redline (actual limit, not just the red paint on the tach) of 6700 and the rev-up is 7300, HR is 7650 I think.

As long as you're like 7300 or lower on a DE you should be fine. Keep in mind the rev-up has the upgraded oil pump which is necessary for it to hit the higher rpm compared to the base DE.

 

I'm HR on an UpRev custom 93 map with ARC license. The needle pins at 8000, up from 7600 stock. Still smooth as butter though.

 

Yeah I'd stick to the stock pulley. You could go with a lighter weight aluminum driveshaft though, I don't know if anyone makes a direct fit for the AWD models but most medium sized towns have a driveshaft shop less than an hour away if there aren't any near your location.

It's a little less of an upgrade compared to going with a lightweight flywheel but it would be a comparable (maybe slightly better) performance upgrade to lose 15 lbs of driveshaft weight compared to 4 lbs of crank pulley weight.

 

Yeah, no such luck on an X model lightweight driveshaft. I’d even settle for an aluminum W tunnel brace even though it’s not rotational mass loss. There’s a limited market for the V36 sedan and its limited 2 year production run. Some G37 parts are compatible but it’s hit or miss. Even the vendors selling the stuff aren’t sure if certain pieces will fit, sway bar end links being just one example that gave me heartburn. Soldier on I guess.

 

Call around for a driveshaft shop, they can just custom make one. It's usually like $500 or so.

They'll tell you exactly where they need the measurements from, usually it's center to center of the existing u-joints.

It's even easier for them if you take your driveshaft off and just let them have it for a few days, that way there's no confusion on the flange for the differential.

 

I have a 06 G35 coupe rev up 6-speed with lightened flywheel and a high output alternator and idler delete. Do you think it would be safe to put a underdrive crank pulley on? Has intake plenum spacer, bigger throttle body and spacer, intake, and full exhaust?