Nismo 350Z

NISMO had it easy with the Spec V. In stock form, the fastest of the Sentras is far from its potential and NISMO, as we saw in last month's test, can work wonders with that scenario. Things aren't so easy in the land of Z. The 350Z, though certainly not at the limit of its chassis' capabilities, leaves relatively little on the table in stock form.

Take the Track Package 350Z that was the starting point for the NISMO R-Tune 350Z we test this month. What does it beg for? It already has big power and wads of torque. It already has big, forged Volk Racing wheels, and healthy Brembo brakes. It's already low, firm, well damped and responsive. The 350Z is not without fault, but none of its faults are very obvious.

NISMO took to the Z like any other car, though, simply trying to add to the car's natural strengths. Power was attacked with the standard breathing mods.

Both the S-Tune (the silver one) and R-Tune (the blue one) cars we tested have NISMO's 304-stainless-steel cat-back exhaust. The stock exhaust's bottleneck is the Y-pipe that merges the flow from the two cylinder banks. The NISMO system, then, has to replace this part to get any gains. Before the Y, NISMO uses 2.4-inch tubing, afterward it's 3-inch. In total, the system weighs 9 pounds less than the stock one, but makes only about 4 hp in our dyno tests. (We had a stock Track Package Z along for all our testing so weather conditions wouldn't skew the results.) The exhaust sound, not surprisingly, is beautiful. The VQ35 is probably the sweetest-sounding V6 to come out of Japan--a huge improvement over the flatulent VG30--and NISMO's exhaust lets you hear it just that much better when you play with the throttle. At idle or light cruise, though, it's hardly louder than stock.

That's the extent of power mods for the S-Tune level (parts that are emissions legal and covered under a three-year, 36,000-mile warranty if they're installed by a Nissan dealer), but R-Tune starts looking quite good from here on out. At least on paper. The cramped exhaust manifolds are replaced with tubular headers crafted, again, from 304 stainless steel. The headers feature stepped primaries that grow from 1.625 inches to 1.750 inches before merging in 2.25-inch collectors. Next, the R-Tune gets a mild set of cams. Valve lift is increased from 0.376 inches to 0.426 inches and duration steps up from 240 degrees to 262. The cams offer little downside, thanks to the Z's variable intake cam timing. With the system automatically dialing out valve overlap at idle and low rpm, there's none of the lopey idle you might secretly wish for. Instead, there's just a subtle occasional misfire at idle and the same responsive, torquey bottom end the engine already had.

The cams do hide one dirty little secret, though. Labor costs. Installation is, at best, an eight- to 10-hour job. It's a similar story with the headers, which typically take five to six hours to install. Start counting parts (four cams, two headers) and labor hours, and you start to understand the appeal of the inline four.

The crowning underhood jewel, at least acoustically, is the cold-air intake. Now, to be perfectly fair, the stock intake is also a cold-air intake, taking its air from ahead of the radiator. The aluminum NISMO piece adds some healthy acoustic resonance tuning, and with that comes a howl that's easily the car's most rewarding aspect. Romp on the throttle and the combined sound from the intake and exhaust is soul stirring. Do it in a tunnel and you won't be able to stand up for an hour.

The bad news? Only 10 hp on our dyno. Nissan claims 23 hp for all this work, and if you live in Texas, Michigan, or any of the other quickly dwindling Edens where they still sell gasoline, we'd advise you to believe them. That kind of power isn't going to happen on the regurgitated dinosaur excrement the California refineries like to call premium gas. Even in stock form, the 350Z lives its 91-octane life on the knock sensor, and with the ECU retarding timing almost as fast as the NISMO parts increase cylinder filling, there's no power to be had. What NISMO needs for the octane limited is an ECU with a less aggressive timing map, but it doesn't have one at this point.OK, enough crying about our gas. If you live in the land of 91, be prepared to splash in a few gallons of $6.00/gallon 100 octane at every fill-up if you want all those parts to make anything more than noise.

So let's talk suspension. NISMO seems to think that if it tells us the spring rates, we're all going to whittle our own Zs out of Popsicle sticks, so NISMO guards them like formulas for nerve gas. That leaves us with little but the droll observation that the NISMO springs are stiffer than the stock ones. You probably already guessed that. You probably didn't guess that in some conditions, the NISMO suspension (springs, shocks and stiffer hollow anti-roll bars at both ends) actually rides better than stock. No, really.

The stock Z is what we like to call "choppy" on the rhythmically misaligned concrete slabs that make up L.A. freeways. NISMO seems to pair its secret, stiffer springs with shocks that have slightly less low-speed damping. In shock-talk, low speed doesn't mean driving slow, it means big body motions, like the ones that makes us use the word "choppy." In most situations, the NISMO suspension feels firm and perfectly damped, but seldom harsh. If you're about 175 pounds, you may find that the driver's seat is tuned to exactly your natural frequency. More than once we found ourselves bouncing around inside the car when the car itself seemed to be smoothly and obediently following the road.

Other than that chop thing, which only seems to matter if you live in downtown L.A., the stock Z suspension's only fault is persistent understeer at the limit (no, the limit is not when you spin the rear tires). The NISMO suspension doesn't improve this. Grip is increased, sharpness sharpened, but the balance is about where it was before.

That's all S-Tune. R-Tune adds a clever, adjustable clutch-type limited slip. The NISMO limited slip can be set up as a two-way (works under acceleration and engine braking) or 1.5-way (same thing, but it's not as strong under engine braking). We recommend 1.5-way. The pre-load on the clutch packs is also adjustable by removing the right-hand stub axle and stuffing a 19mm socket in the hole. The three settings give a breakaway torque of 50, 69, or 101 lb-ft.

If you disassemble the differential, of course, you could also lower the breakaway torque even more by re-arranging the 10 clutch plates on each side of the diff so that some of them are inactive. NISMO doesn't officially state this, but it doesn't have to, that's just how clutch-type diffs work. The NISMO diff is also stronger than the stock one, since it transmits torque through four pinion gears instead of the stock diff's two.

We don't know how the diff in our car was set up, but whatever it was, it was too tight for the street. On the track, where you brake, turn, and accelerate through every corner in the same smooth, predictable fashion, a tight limited slip can be good. Drive a narrow, twisty mountain road at night, though, and you won't be laying into the gas at the apex and holding it down all the way to the next corner. Not with 249 hp at the wheels. Instead, you tend to feed in and out of the gas as you try to stay between the yellow line and the white one and figure out when this damn corner is going to end.

Rolling on and off the throttle like this makes the rear wheels lock together and release every time, which makes the front tires push and then grab with every move of your right foot. That makes you look like a swervy monkey. Don't believe us? Look at the skidpad results. The S-Tune car, which uses the loose factory limited slip, pulled an impressive 0.98g. The R-Tune Z, with exactly the same suspension, but the NISMO diff, pulled "only" 0.95.

Based on our experience with Project 350Z, we'd still recommend the NISMO diff, but set it at the loosest setting and if it still does the swervy thing described above, take it apart and start swapping discs. Remember, it took us three tries to get the KAAZ diff right in our project car.

You've been wondering about that body kit, haven't you? Here's the deal. The air dam is made of the same flexy thermoplastic stuff as the front bumper, so when you ram it into things, it won't get as screwed up as your typical aftermarket stuff. The front bumper on the R-tune car is from Japan, though, so don't expect to get that with your frot spoiler. You'll only get the bottom lip. The NISMO side skirts are a direct replacement for the stock ones. You don't tack the NISMO stuff on top, you take the stock ones off and put the NISMO ones in their place. That's the way things should be.

Finally, the wing. It looks exactly like the Japanese NISMO wing, but the Japanese one is fiberglass, and that just won't do. The U.S. version is ABS plastic.

The R-Tune Z was also packing NISMO brake pads, which are kind of difficult to evaluate without harder flogging than we managed. The stock Track Package Brembos feel great. The same brakes with NISMO pads also feel great. Our measured stopping distances with the stickier tires and the NISMO pads, though, were slightly longer. What these numbers don't show is that the NISMO pads actually faded from 119 feet to 127 feet in four stops. This is a sure sign that the pads weren't properly bedded in before our testing. Had we retested them after a proper cool down, this fade would probably be gone. We didn't think of doing that until we were already home. We're not always as smart as we try to be. n