hiz-n-herz

iTrader: (11)

Before you guys tell me the best mod is a DE and time behind the wheel; I know I could always use help there

Question: If I want to go FI, would a Supercharger or Turbo better for the track?

The reason I ask is in the Nov issue of C&D the author mentioned that with the z's NA motor, they were able to modulate the pedal more precisely to get the right amount of power-induced oversteer upon corner exit if needed (infering that this was trickier in turbo cars.)

Surely you dont want to get a sudden increase in boost at that critical moment (like one might expect in a turo car). I would expect that the power curve on a supercharged car would be more linear with fewer surprises and thus might be better for track use. (I am guessing here; I'll admit I am far from being an expert)

FYI, I have an 06 GT 6MT, completely stock. I am not satisfied with the power, nor am I happy with the suspension. I am leaning towards NISMO s-tune suspension (I don't want to drop it much and still want a reasonable ride, but I don't care for the linear rate OEM rear springs or the OEM rear shocks which seem overly-compression-damped.

I am contemplating a Vortech SC or greddy TT or JWT TT. All on low boost (5-6 PSI on stock internals). I don't need to be the fastest car out there. Nor am I looking only for straight-line performance.

I am coming from a 97 M3 with springs (.5" drop) and Koni shocks and no engine mods. I had always wanted an e46 M3, but I just really like the 350z: Looks, ergonimics, intimate 2-seater cockpit (reminds me of my old 91 CRX; but with ba11s!). But I want to match the power of an e46M3, So 4.8 0-60 and 13.2 1/4 mile so I don't feel like I am missing out!

I appreciate your comments and feedback...

Stack

With the right forethought and planning, you can have a turbo system that will still be somewhat linear as far as throttle response in the context of road course driving. Keep the boost to a moderate level.

Remember... on a road course, if you're doing it right, the engine will spend most of its time in the upper RPM ranges anyway, where a SC might lose something to a Turbo. So the old supercharger wins because of the low-end response doesn't really apply. The mid-turn properties probably will be more linear with a SC, but with practice, you'll adjust your driving style accordingly.

You have to be sure to match the turbo behavior (boost and RPM range) to your driving style, which brings me to my next point...

KNOW YOUR DRIVING STYLE!! .... DO SOME DEs WITH THE CAR BEFORE BOOSTING IT!! (You said before we tell you to do DEs, so I waited til after I answered your question )

mhoward1

Ti tell you the truth, I like the throttle response of a s/c over a turbo. Even with a good turbo, there is some lag if you let the RPMS drop, or are off throttle. THis can be delt with with Left foot braking, but I still like the N/A response of a s/c. It's all Personal preference, but I have had all three. I liked the N/A motor the best, but it lack real power. The Turbo had great power but it was peaky in the cars I had, and the multiple s/c cars have been a nice compromise.

hiz-n-herz

iTrader: (11)

But you are right. I need to do some DE's with this car. I've done zero. I'll be sure to do some before boosting it or playing with suspension.

hiz-n-herz

iTrader: (11)

Were they twin-screw or Turbine?

mhoward1

I have had one roots type and one twin screw.

filanj

iTrader: (1)

twin turbo all the way

mhoward1

why would you say that's better for track use?

hiz-n-herz

iTrader: (11)

WEre those on the z or other cars? Were they on tha same car at different times?

thanks...

knight_white99

iTrader: (5)

I'm running a JWT twin turbo on the track. The turbos are fully spooled at just 2500 rpm, so you get power virtually all the time if you keep the rpms above that. Also, the power is amazingly linear. I have seen the dyno plots too - HP is a straight line all the way up.

The power is very easy to control on the track and very linear. It almost doesn't feel like a turbo motor. It feels like N/A, just a lot stronger. You can't beat it.

Contact VRT and they can hook you up. They do great work and you'll have linear power that you can use on the street or on the track.

Kolia

iTrader: (2)

Interesting topic. I’d instinctively say to go with a positive displacement SC (Roots, Eaton or Lysholm) but I guess a good turbo setup would work very well also.

I’ll side with Stacy and recommend you take your car to the track first. You have an ’06 with the revup engine. Take some time to appreciate that power plant. I love mine (’05 Track have that engine too) and, although more power is always fun, it’s pretty strong in OEM trim. It revs very well and keeps on pulling all the way to the red line.

Plan you upgrades wisely. If you go FI without touching anything else, you won’t be much faster. You’ll just overload the tires, brakes and suspensions well before you actually run out of power.

mhoward1

No, two different cars with different size engines. The power levels were vastly different, but I was comparing the overall characteristics.

Eagle1

iTrader: (2)

I have used both supercharger and twin turbos on my car, and like both very much. The sc was the ATI Procharger at 7psi. It put out 350rwhp conservatively tuned, and with a Tein flex/edfc coilover set and stiffer sways, and bigger wheels and tires, it was an excellent performer on the track as well as a reliable daily driver. The centrifugal sc is really a belt driven turbo, and as you are up in the high rpms on the track all the time, it was a beautiful and responsive machine with great sensitivity to your throttle inputs mid turn...which of course is what you want. Since you are going to be limited to the rwhp you can put down with stock internals, if you are not going to build the motor, then I would go SC. There is no advantage to turbo in that situation, other than it is quieter than the jet engine sound of the sc, and you will get better gas mileage. The sc is also less violent on your stock internals, less expensive and complex to maintain, and cheaper to buy and install.

I would not do a positive displacement roots or eaton blower. They are great down low up to 3,000 rpm, but all done in at that point. That is good for street light stuff, but not as good on the track. The best imo would be a twin screw lysholm or whipple, but I am not aware that any are available for the VQ at this time. You would have to customize the entire set up and that is probably too time consuming, expensive and risky at this stage.

If you are going to build your motor, then I would go turbo, and probably twins. I like the JWT set up, and it is very low in the turbo lag department, but it is still there. The throttle approach is different and takes some getting used to. But with the built motor and 500rwhp......shazam you are in a whole 'nother world of performance. Now you are kicking viper and vette cars. You will need to seriously redo your suspension, and BRAKES. Expensive, but it is another quantum leap above the worthy and esteemed E46 cars.

Good luck, have fun, and drive safely.
Ed

knight_white99

iTrader: (5)

Eagle1 might have as much experience as anyone with the supercharged or turboed VQ motor.

Eagle1

iTrader: (2)

But I cannot put winner of the Silver State Classic in my sig, as perhaps you should!

knight_white99

iTrader: (5)

LOL... Thanks for reminding me, Ed! I had been thinking about adding that.

sentry65

iTrader: (11)

I agree that with a built motor, going turbo might be the better rought. The only thing I don't like about the JWT and TN kit for that matter is the top end really tapers off. The greddy and APS have more consistent torque up top, but the greddy (and ST kits) are probably the turbo kit with the most lag (not really considering PE or the other lesser known kits)

SC's will generate less heat than turbos though, which may or may not be an issue at the track. Seems most people who do roadcourses with turbos do alright with managing heat.

on an off topic note I kinda like the jet engine sound of SC though compared to the dentist drill sound of turbos

Eagle1

iTrader: (2)

All good points. I like your process of thoughtful analysis.
And last point first, coming into an indoor garage with the SC sounds like a fighter jet landing on a carrier....great stuff. Tunnels and walled underpasses that throw that reverberation are also neat, and if you do headers, and get on the gas, that combination of low growl with the SC whine is pure Beethoven to a car enthusiast.

Heat management is key. Bigger three core aluminum radiator, oil pan spacer, big oil cooler and thermal barrier and dispersal coatings are a big plus. I run 13 quarts on my baby, but that is because I do track it about ten times a year now, or more.

If you build the motor, then the top end taper is not really a problem. You are shifting at 5k rpm....as opposed to 6500 with the SC, to stay in the peak power band. You do not need to have any issue with this unless you get to track where in fact you can be getting above 5000 rpm in 6th gear.........GOOD LUCK finding that scenario! I have driven Road America, though not in my car, which has some awesome straight sections...four really good ones for high horsepower cars....but I do not think you will get into 6th and flat out and struggling with being above 5500rpms and "tapped out" on power. The only car that I have been against on the front straight at Cal Speedway that could pull on me, and that includes Z06 Corvettes and Vipers and 996 TT...was Mike A's 700 JWT TT unit, and that was only at about 3/4 down the long front straight where the additional high speed torque could come into play. Remember, at only 12psi of boost the smaller 530 TT is still throwing 566 lbft of rw torque....and at 1bar it is well over 600. that is just about as much as any young man is ever going to need, or can find a place to hook up! going into the Roval at Cal Speedway with the speedometer around 175.....My primary concern is backing it down on turn in for Turn 1 so that I am stable and lasered on the right line, at below 150mph, so that my shorts stay dry.

However, if that is an issue.....go to the JWT BB 700 units....and just be sure you are reading up on your aerodynamics and look into some downforce from a wing!

knight_white99

iTrader: (5)

I don't feel that there is much tapering off of power in my car above 5000rpm. At Buttonwillow last weekend, my car was still pulling hard at 6000rpm plus in 5th gear on the back straight (going CCW after the Riverside sweeper). Maybe it's because I also have the Nismo cams and Crawford plenum that seems to increase air flow at higher rpm. Mraturbo thinks my car at 6.8 psi is making similar power to other JWT TT cars at 8 or 8.5 psi.

Heat is an issue that needs to be addressed. Larger radiator and oil cooler as a minimum. I will be getting a vented hood soon for some additional cooling.

You are running 13 quarts of oil, Ed? Where do you put it all? I am sure that you have the JWT spacer for an extra quart of oil, and maybe another quart in the oil cooler and lines, but what about the rest of it? What kind of oil temps do you see after running hard on the track?

While I haven't found a track yet that I can get up to 5000 rpm in 6th gear, I was above that in the Silver State Classic, and for quite a few miles, and that was even running with the taller 3.35 A/T gearing. You guys really should try it - it's a blast!

sentry65

iTrader: (11)

Eagle1, I wasn't meaning top end as in gearing - I should have clarified, I meant above 4500-500 rpms all the dynos I've seen look like the torque really starts dropping off with the ST and JWT kits. I haven't ever driven a Z with those kits, but that's been my observation

I'm sure it isn't much of an issue when you're going fast anyway

Otherwise I always thought you'd want to shift at redline to maximize your hp and gearing when you're trying to go as fast as you can

my car with the APS oil pan and an oil cooler takes about 8ish quarts of oil