I should have known better. This was around 1/2 tank, maybe a little less. I had starved a few times before always in big rt hand sweepers, but with so many right turns this was way worse. Gonna have to look elsewhere for weight savings:p

4 events in (all on asphalt -- Bristol, Philly, Bristol 2.0, local BMW club), I've learned that this car is *difficult* to drive at the limit. It's really loose, and right now probably just too stiff for 285s, particularly in the rear. Even on a tight local course, my codriver (a DSP contender) and I were running fairly mid-range MCS settings on the front dampers and basically bottoming out the rear.

I'm at 1000lb/800lb with factory Nismo bars, and disconnecting the rear at the midday break of our local event certainly helped -- not enough to balance the rear damper settings back upwards though. First I'll be going for some bar changes. I find it ridiculous that the front and rear bars on this car are both 27mm. I would have tossed it out ages ago knowing that. Potentially softer springs if that's not enough of a fix, and if we don't move to 315s next year.

We also found ourselves instantly getting ABS while braking out of a faster sweeper. At first I assumed I'd finally encountered the issue everyone has been complaining about despite having a factory diff cover and HPS pads, but it sounds like the opposite of that problem given the previous discussion.

When I got home, I found some oil spewing out of a loose sandwich plate fitting and probably on to the front right corner, likely getting to the tire and/or brake disc, which coincidentally would have been under the most load at the time. For now I'll attribute the ABS to that unless you guys have other thoughts...

Your spring rates don't seem that out of line compared to others. Get yourself a Hotchkis front bar and lose the rear. It's shocking how much better it makes the car.

How much camber and toe are you running front and rear? I never experienced my car being difficult to drive unless it's on old tires. I built it, though, with keeping it easily drivable at the limit in mind, but don't think I'm far different from others.

-3.5F, -2.5R, give or take. Toe is 1/8in out at front, 1/8in in at rear. Some toe changes could benefit the rear, but perhaps at the sacrifice of camber spec given our LCA adjustment?

I think the main thing is going to be the bar changes though. The front feels great, and the car transfers nicely during slaloms and such, but I should really be able to put more power down in sweepers and through harsh transfers. Offset gates on the bumpy bristol asphalt were nightmare material.

Stiff front bar (Hotchkis) and a mechanical LSD helped a ton for me.
I was happy with corner entry and mid corner balance, but had to be super gentle to put power down because the VLSD was pretty much worthless and the inner tire had so little weight on it.
So the stiff front/no rear helped the inner rear stay on the ground a ton, while the LSD make sure I was powering out with the outer tire too.
The improvement in corner exit was well worth it.

Just make sure the LSD is a clutch type. A Quaife just won't work with the unloaded inside rear.

Wavetec is an option too, I use the Quaife just because it's maintenance free and didn't know about Wavetec at the time I bought it.

I have an OS Giken so no worries there. I suspect the bar changes will put things to bed, especially if we end up on even more tire next year.

I'll be building my 13 Nismo to STU for the coming year. Lots of options trying to decide on so many bits. It's amazing how many choices there are for headers, cats, camber arms, diffs, and suspension. and trying to figure out what offset I need to run 19x11 square.

Umm, why would you stick with 19's? What you want are 18x11's.

Agreed!! You get better handling characteristics, lighter wheel/tire combination and the cost of tires is less.

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I like the gearing offered by the 19 tire sizes. To run the 18’s I lose 3 mph in 2nd which would seldom be an issue at autocross. But I loose 6 mph in 4th which is a big problem for me at two spots on my local track (ncm). I don’t want to ha e to do a bound up dogleg down shift creating turn 16, which is off camber decreasing radius with an entry of 120+ Mph. It’s also not like there are a lot more wheel options in 18. The goofy offset up front makes for very few options. One of the great things about the 350 was 18x10.5 on stock suspension, cheap light available.

It is your choice to do with your build whatever you want too and be for warned if you come hear asking for opinions or just posting whatever you are going to get feedback that you may think is harsh, rude or whatever. Now that that is out of the way your logic goes against pretty much everything that has been posted in the track section on the best wheel selection for track or autocross. Most run 18x10.5 with a NA build with a 275 35 tire. A few of us have stepped up to 18x11s and there are smaller number running 18x12 or 19x12 (those running 19x12 run a staggered setup). The handling characteristics of the 18" tire is much better than 19's so you gain on turn in and exit. Also on a NA car 18's have the same impact as changing your gearing to about 4:08 but probably not that much. After running tire size through a calculator there is only 4 mph difference in fourth gear. You will also gain time in acceleration because you are running a smaller wheel and tire diameter.

I guess if you want to do something different than every highly successful 370z time attack or racecar more power to you, it is your car and your fun! Good luck and let us know how well it works out for you.

I’ve used the internet before, my feeling aren’t hurt ;)
11” width is max allowed in Stu so 12 wide are irrelevant. The 315 width was new in 2019 and very few seem to be run the z34 at nationals and they’ve not been overly successful. Only one bested the fastest z33’s in 2019 (no 2020 nats).
I built my own speed calculator using revolutions per mile and the gearing correct to my car. The 315/30/18’s get me only to 117.73 mph in 4th and the 285/35/19’s up to 123.8 which meshes with my gps data, the 305/30/19 will only get me to 120.99mph which might be worth the sacrifice.

On track I think mine was the only 370 at Time Trials Nationals. So there isn’t a lot of people running these cars at solo nats or TT nats.