Hey 350z guys, quick back story before I delve into the question.
I've been driving a WRX since 2005, in STX since 2008 and love the car. In an attempt to add some variety to my life I parked it for the year, and co-drove some different things. After all was said and done, I feel like AWD may be holding back my progession as a driver, and it's time to rid myself of the WRX. About the same time, the 350z hit the books as being reccomended for STU. I test drove a few and autocrossed one.. and promptly fell in love. This will be my next car.. but the hard question is: Which one?

across the board I'm thinking base package.. I can't think of anything I'd want in the car that's an option package wise. alot of what gets added from other packages is just going to get yanked (seats, sub) or get in the way (Trac/VDC) when I slap some big tires in a non stagger setup. Maybe an enthusiast, just for cruise control (i don't trailer), but that seems easy enough to add after the fact.

Then it comes down to which engine.
Original, Rev-Up, or HR
Right now, math wise, i'm leaning towards the HR cars for their higher output and higher redline. The added curb weight sucks, and it does appear to all be in places where it's not removable (heads, intakes) and it seems there's a few less options around for making more power.

I'd love to hear the input of everyone here though, because clearly you all know more about these cars than I do.

 

If at all possible get the HR. It's simply faster than the other two models. Plus the 2006 rev-up (like mine) tends to burn some oil. I dumped a lot of mods into my NA rev-up and it's probably about as fast as a stock HR. Since you plan on running the car in a competitive environment I do recommend an oil cooler and tune. the stock radiator seems to do fine. I spent all last weekend at Button Willow raceway and monitored my engine coolant temps via PLX device and iPad. I don't think my temps ever went over 205-7.

The stock VLSD is crap.. I wish it wasn't but it is. I'm not sure if STU allows upgraded diffs but a good LSD would be a great addition to the Z. As far as rubber, I'm running a square setup with 265-40-18 tires and like it pretty good. I may go a little wider next time though. Adjustable sway bars will help dial in the ride to your driving style. Again, I'm not familiar with with the STU class but if they prohibit coilovers the Koni Yellows really do the trick.

 

Go to these two threads, Brain Peters won national in str with the Z this year and 03threefiftyz runs in BSP. No need to start a third thread.

https://my350z.com/forum/autocross-r...ross-350z.html

https://my350z.com/forum/autocross-r...l#post10271757

 

Oil cooler isn't legal for STU (not that i haven't written my share of letters for it)... but a tune is defintely in the play books. I've built one STX car before (my WRX) and i'm going to take a much more detailed approach to this.

The stock VLSD is defintely going away, and is in the rules. i don't have enough experience with RWD builds to choose right now, but i'm torn between a clutch type or a wavetrac, currently favoring the clutch type from my readings.

I've read both of those threads back to back. they're great, and i've taken plenty of setup notes between the two, but they both seem to be coming from a point of them already having the car.

Everyone who's put a car in a class that already owned it will usually have some after thought about which would have been the better optioned car, or the perk of a different year, some sublte newonce that makes the difference down the road. It's less of a situation in BSP, but with STU and it's inability to perform update/backdate, alot of the car has to sit as it's built and that's why picking the right car off the bat is so important.

Maybe Brian wishes he had an HR, or maybe he chose the 03 for it's lighter weight and torque numbers.. and how will that choice impact his gearing now upon switching to a considerably larger tire? These are all factors that I'm trying to take into account before i drop 10-15k on a car.

 

With normal out of corner accel start speeds (corner exit under throttle), the DE is going to have more thrust than the HR. Honestly, run the DE up to the point of explosion, around 7200, and you pretty optimal gearing for an ST car IMO with the DE. There are going to be very few courses where an HR will be of benefit. With the STU move, there is even less reason to go to an HR, since you can run a pretty tall 285/35 RS3 out back. I am definitely pushing past the limit on the BSP car. At Nationals I ran it up to 7450 and was mugging the rev limiter on the East Course. Going back to STU, even though you can run a larger tire, in ST...you go with the lighter option given relatively close power (less than 10% and equal tq). I have been giving some thought to running the HR motor in the BSP car, but worry about some of the electronic and other teething issues. Plus, I can't upgrade the slave cylinder, which is a problem for Pro's. I have no doubt a full spec HR will make in the 325whp area on ethanol, though, which is tempting.

 

that east course really ran everyone out this year, huh? Try it in a NA MR2 (not spider) on street tires.. touching the brakes hurt.

The two factors getting me thinking about gearing is the tires and the engine... i'm probably going to wind up on the dunlops, which means 285/30-17 and not 35.. gonna loose a few revs there off the top speed, but they considerably better in our colder environments up here in MN.

The other one, is the variable valve timing.. i know this has been a source of some good gains on more than a few cars, and the HR engine has it.. my hopes are that with an aggressive tune, i can get back that low end torque.... or am I just completely wrong/crazy/stupid?

 

It's actually standard on the intake side of every Z and also on the exhaust side of the Revups and HRs. Minimal gains across the board for all motors. It was primarily introduced for emissions purposes and not nearly as good of a system as the intake cams received.

 

Dunlops are fine, but I would leave them at home for Nationals. Hot+Concrete=RS3's. The 285 width should help out the dunlops, though. A little extra area to warm up.