Whew....that is like asking "blondes, or brunettes?"...or whatever are your two top choices. They are "all good", just a question of preference really. The subject has been beaten to death and beyond on this and many other websites so please understand, what your will get from me has to be a subjective reply with which many could take issue, and legitimately so. ( I am getting married in July to a blonde, so that is now on the table and out of the way as long as we are into "full disclosure").

I have previously run this car on an ATI Procharger for 23,000 trouble free miles, with about 350+rwhp on stock internals. That was the limit I wanted to go on the stock guts, and while there are some folks that do more.....let see how they do after 20k on the odometer, with a score of track days, before the claims of reliable 400rwhp on stock guts are trotted out as proof. Conservative tuning and religious maintenance if you go FI. Otherwise, be prepared with your wallet because it is not a question of "if" you will have a catastrophic failure, only a question of "when".

The supercharger is easier on the internals than a turbo, cooler running, less complex, there is the power supply is "seamless"....no lag. It really kicks in after 3,000 rpm and when running on the track, rarely below 5,000 rpms, shifting typically around 6300 to 6600rpms. She is a loud baby with an SC, you get lower gas mileage because the parasitic belt is always pulling, but you keep the stock pistons and compression so power is still good below threshold boost levels. You do not reach max boost power in an SC that a turbo will because of the parasitic loss, but max boost on the turbo is so high up in the rpm band, and after torque starts falling off, that you really cannot use it...so I think too much is made of what the power is at max output, and what one needs to be looking at is the max power that is useable in a practical scenario.

The "slam" that you feel with a turbo when it kicks in, which gives the felt impression of power, is violent on the parts, and contributes to failure. It is powerful, but you have to remember that the SC car is "ahead" on the power delivery and thus the turbo is behind the scratch line and has to catch up to the SC. (In this case we are talking centrifugal SC, which is very comparable to a turbo, just belt driven. A positive displacement style blower - of Roots/Eaton type - gets power on hugely at low rpm but is over and done once it gets to about 3,000 rpms, so it is good for drag but not as much for road racing. A lysholm type sc is awesome all the way up the band, but none have been configured to date for our motors to my knowledge, so no point talking about why it is the best of them all. But check out the power under the curve of a Whipple charger compared to a turbo or other SC and you will see why.)

The turbo is quieter, gets better mileage, and gives huge power. You can get more power on the sc with different pulleys, and adjusting the fuel management system. But basically, if you are NOT going to build the motor, the car has power limits imposed on what you can do by the specs on the stock rods etc. The parasitic loss on the sc subtracts from the ultimate rwhp that you will get. But the "dial down" that you need to do for the violence of the turbo kick also subtacts from the ultimate rwhp that you will get and frankly, you wind up very close to the same place, or else you are kidding yourself and just skating closer to the edge. Some folks will make it by, others will not. Either way....it is not intelligent, but a random outcome as to whether one survives it or not.

SO, my choice for a stock motor would be the SC. You will get equivalent power, but more smoothly useable power, and on a car to use on the track, the ability to have instantaneous, predictable power is very advantageous as you are dancing along the edge of the limits of tire adhesion in a turn. A little bit of turbo "kick" as you at the limit on corner exit will send you sliding, and that is a nasty thing. So the SC is all over better in this regard. If you are not going to track the car, then I would go turbo. The better gas mileage, quieter engine give a nicer street experience, and the fact that it would be at a disadvantage on the track......is not a disadvantage if you are not taking it there.

The second scenario (of three), is to go with a built motor that you then apply forced induction to. In that scenario, whether you track it or not, go turbo. You can put out incredible power, way beyond what you can use on the street or the track, pull your testosterone back just a bit and dial in the power for what you can responsibly use, and which is well below the spec limits for the parts, and by doing so with the use of smaller turbos have boost threshold at 2,000rpms with minimum 400lbft of torque AT THE WHEELS, and virtually no lag. The car will have peak power at 3800-4000 rpms so shifts will be around 5,000 rpms, so you are not working it as hard, although you will have 8.5 to 1 static compression pistons and so in that little window of 600 to 1600 rpms it will be a bit anemic. I have been running my car on the JWT TT using his 530 BB units, with adjustable boost, and that is quite slick. I can run anywhere from .7 to 1.2 bar of boost, but typically just run .9 bar on the track with race gas, and .7 bar on the street on premium gas. (You do not need 479rwhp and 566 lbft of rw torque on the street.) Now, if you want to get silly, you can go with bigger turbo units, like the 700 BB unit from JWT, or some bigger Garretts or Greddys or whatever you want, and you will have "slam" and you will get dyno numbers that are huge......but just remember you put out that much power, and you will have durability and reliability issues, even with a race built motor. You cannot escape the laws of physics when it comes to force. Head lift, heat, drivetrain issues with the clutch and diff.....you have to respect that you are generating very big "ka-boom" in those six little cylinders from your 215 CI displacement motor to get bhp approaching 1,000 bhp...........do you think you can lock that to the ground and use it?? Let me spare you the head hurt...you cannot. Around 125mph in fifth gear headed to sixth as you streak to 160mph on a long straight you will indeed feel the advantage on the track, but in 3rd and 4th gears, where you live most of the time on a road racing circuit, you will not. They are awesome, fun and fast. But I would rate it akin to having a .357 and a .44, both magnums. After awhile, just about everybody decides to shoot .38 specials in a .357 mag, and let their friends try a few mag loads out of the .44 until the concussive blast gives them a headache.

The third scenario, and one not talked about a lot, is to run a built NA motor. In many respects NA power is the best power. On this car you can get up to almost 300 rwhp with a built motor, cams, headers, exhaust, intake mods etc., and improve it even more with a lightweight flywheel and clutch, a limited slip differential, and lots and lots of suspension changes, such that you can run very fast track times on tracks, to the point of taking out many boosted cars. Because, in the end, it is driver skill and the ability of the car to take turns at speed that make for fast lap times. And big power is not the only answer. It is part of an answer, but it is third in line behind driver skill and suspension...not first.

Hope that helps.

Cheers.

 

Nope, just another regular guy. I have spent a lot of time reading books on as many aspects as I could find, including suspensioin geometry, aerodynamics, tire design and construction, and of course forced induction and race driving, listening to people who know more than I do (which is a lot of people), going to race driver schools and practicing on the tracks......and paying attention. Studying before I go to the track, and as I drive really focusing on braking points, turn in points, apex and driving line, exit points, tire response and how the springs are loading and unloading and how to induce the car to do things with throttle and brake as well as the steering wheel. It just takes time and practice, like everything else. And a lot of modesty. Because let us face it, no matter how much you know or think you know......you should know enough to realize you cannot negotiate with a concrete wall going 175mph.....you just cannot. So back off, keep modest, and stay alive. Remember, the most frequently uttered words by young men just before they die are..."hey, guys...Watch This!" As Dirty Harry said, "a man has got to know his limitations".

Cheers.

 

Definitely words to keep in mind at the track. Well said.

 

Thanks Eagle1..I have skirted with the thought of going staying NA and just maxing the car out with drivetrain and and suspension mods while improving my driving on the track. I love the magic of boost but my greatest addiction is to grip and more grip. Now the prospect of increasing grip..........

 

one of the most informative threads for a long time. Should be stickied.

 

It is possible to have too much tire. But this car weighs 3550lbs more or less, and it has 300bhp with a couple of little things like a popcharger and z tube. If you put in a Motordyne 5/16 iso thermal plenum spacer and a catback, you might run to 312-315bhp at that point. Bottom line...plenty of power to have fun on the track.

If you want GRIP....you can go 275/35 treadwidth all around on 9.5inch wide rims, with something like a Hoosier, or an RA-1 from Toyo, a Nitto NT-01, or a Pirelli Corsa all of which come in 18 inch diameters. You may need a 3mm spacer up front, but backs should be fine. If you run FI, then bigger in back is worth while, and I run a Nitto in 315 (actually it is 323mm wide) on a 10.5 inch rim.

I like the Enkei NT03+M wheel, light and not expensive. But just get what you want as far as looks are concerned as long as it is very light and very strong. Forged one piece wheels or the patented MAT process of Enkei are the two ways I would consider most strongly.

BUT, then you have to deal with a suspension mod package to deal with all that grip.

A powersteering cooler will probably be necessary with that much pressure up front.

IF you can get a good one, an adjustable front upper control arm dialed to 3.5degrees negative camber for the track.

Stiffer sway bars front and rear, like Stillen, but there are plenty of choices.

Strut tower braces front and rear. Stillen has a cheapie for the rear. The front is very difficult and thus expensive. VRT has a good one.

Coilovers, and drop the baby an inch all around.

A roll cage or harness and roll bar in the car with six anchor points will stiffen up the chassis a lot.
If you do not do a cage, or roll/harness bar, consider an underbody ladder brace to dampen the torsional flex in the body.

Bushings, like Nismo, all around.

Brakes. The stock won't last, nor will the Brembos. If you get going fast, you will need bigger and better brakes. Or go three laps and be done for the day.
Stainless lines, Motul 600 RBF or perhaps SuperBlue. On NA any of the quality big brake kits will do you fine.

For drive train I would go with a lightweight clutch and flywheel. If you can afford it, a carbon single disc because of its quiet and the ability to slip it. If not, go JWT. And a limited slip diff. If you are really aggressive then a mechanical clutch type such as Nismo,Kaaz, Cusco. If you don't want the chatter, and can be less aggressive, then Quaife.

Move the pedals to help with heel/toe downshifts. Consider a short shifter to speed the throw between gears.

That ought to do you more than well.

 

Wow, great thread.

 

Once again simply awesome stuff Eagle1..Here is what I've done over the last 3yrs and the car is absolutely a dream to drive..265 35 18 on a 9inch rim up front, 275 40 18 on a 10inch rim rear,stock Brembos with hawk hp9 up front and hp plus in the rear with stainless lines all around(no issues with brakes),eibach sways,cusco upper control arms,GTSPEC braces,Stillen rear brace, tein basic, full exhaust with headers test pipe(track only),350evo shorty shifter,injen intake,motordyne 5/16 spacer, engine torque damper and I actually disconnect the ac compressor(worth 11hp on the dyno) before track duty. 327hp with Royal Purple 5w 30. In addition to the above I strip the car down to a competition seat with a harness bar and a six point sparco harness. Needless to say I have a lot of fun with this set up and the car is a dream to drive..However, I still have significant amount of body roll, wheel spin on slow speed exits(I have to be too gentle on the throttle) and a push in slow corner entries. What do you think?

 

I think you have yourself one heck of an impressive set up!!!!

Descriptions of what is going on with words are much harder for diagnosis than watching or riding, but given the choices you have made on equipment, you know what you are doing. It is an odd problem. Body roll with all the stuff you have done to the suspension to secure a stiff platform sounds ....well it sounds counter intuitive. There is plenty there to address understeer with some tuning of what you already have it seems to me. If you have Tein coilovers on the car you probably dropped it almost an inch all around. And that would help with roll. But let's explore together with some questions and thoughts, and maybe we can work it out.

Is your front sway bar set on soft or medium? And how about the rear?
(Think about running front medium and stiff rear).

What is the negative degree camber setting you use on those Cuscos? (More negative should help improve grip and turn in, and reduce push, up to say 3.5 degrees negative....I don't think more than that would be a good idea.)

Do you have the full ladder underbody brace? Or just front and rear laterals?

What stiffness Tein springs are you running....10kg or 12kg? If you are using 8kg you have your answer right there. What are your dampers set to? (One reason for roll could be excessively soft spring stiffness in the front)

Do you have a front strut tower brace, or are you running only the rear? A torsional chassis flex could be significantly reduced in the front with an STB, but that is not going to explain "roll" of the type I think you are talking about.


Is the wheel spin on the inside rear tire, or both of them, during corner exit? Do you have a limited slip differential? (If it is the inside rear tire then an lsd should help you to get the power down on corner exit better without spin).
If both of the wheels are spinning on corner exit, then don't push on the throttle so hard so quickly...squeeze it on. More importantly, as you come on throttle hard coming out of the turn...before you wheel spin in the rear, are you getting any "push" on the front?

Slow speed corner entry push.......eek.....what is happening to you at high speed turns? Assuming your driving lines are "true", you ought to be having high speed push as well. Are you still on the brakes in a "trailing brake" technique as you turn in on those slow turns, or off the brakes at that point? (In other words, are you exceeding tire adhesion by putting braking demand on the tires while also turning them?)

Why are you using rims with one inch difference front and back, but only 10mm treadwidth difference? You could use a 9.5 inch rim with 275/35 all around. Or 265 all around. Your set up is putting very significantly different circumference and overall diameter tires on the car, as between front and rear. You have a much bigger sidewall in back due largely to the aspect ratio, (35% of 265mm, vs 40% of 275mm!!!) compounded by the bigger treadwidth against which it is computed. I would run one of those same size tires all around, and not care if it is the 265 or the 275, as long as they were all the same, and on the same size rim. (the one in back is too big a rim for the tire width and therefore unnecessarily heavy). This elimination of wheel stagger will help with understeer ("push"), as will the front UCA adjustment. Stiffer sway bar and spring settings should help with the roll.

Let's see if some of other "team" members out there can catch something else to consider doing to help you out with this.

 

Man, I feel like a complete novice..... but I'm learning.....

 

Me too!
The universe of what I do not know grows exponentially with the additional knowledge I gain, it seems. The old conundrum.."you don't even know what you do not know!"

 

Every answer leads me to 5 more questions...

 

Great answers...My thoughts are similar to most of yours except for the piece on tires..I run med/med on swaybars so med/stiff as you suggest, should help...I can also dial in more camber on the Cuscos..I also have the front lateral and the two braces in the rear(GTSPEC)..No STB..Wheel spin is on the inside tire and there is a push before it happens...I have'nt experience any high speed corner issues which may suggest that I'm a little too aggressive on the slow speed corners. I've learned how to trail brake and so have no issues there..It's not a technique that I use in the kind of corners(hairpins) I'm having trouble with...now here is the part of your response that I think nails me...Wheel and tire package....Three years ago I got a great deal on a set of lightweight Konig Tantrum 2s (3pc) that someone had ordered for a 350z and backed out of the deal..I paid $600 for the set shipping,included from CA to NY...For the tires,I am running what may be the last of the BFG R1s still in circulation..Once again a friend of mine with a Saleen mustang bought two sets(265 35 18 and 275 40 18) and never used them. I paid $800 for both sets.The tires are no longer being made and the rims are no longer being so I guess for a change utilising your suggested format as well as stiffer springs and an LSD. I'm to Pocono next thursday so I'll try the swaybar settings and see how what kind of an impact the med/stiff setup has..You are the most helpfull person I have not met..Thanks Eagle1..

 

That additional information is very helpful!
Since you have two sets, that means four of everything in tires. Can you fit four of the 265/35 all around? They should fit on the 9.5 rim. Even though the back rim is wider, and a smidgeon heavier, you will have equal tires all around and that has to help. Definitely go stiff on the rear sway, up from medium. Then see what happens. (It is not good to change too many things at once because it gets confusing as to what is working and what is not). But if this helps, it might help enough to keep that rear wheel down a smidgeon and to reduce the push too. Then get a feel for how much more you need to do. As long as it is better, you will be happy and know you are faster and safer, and then you can try another step in the process. Have fun!

 

Wow, a lot of information...and a obviously a lot of work to do to get to a competitive stage with my car. My first and only experience at the track was last year with a WRX (wagon). A lot of fun, but a lot of body roll...I mean a lot, but surprisingly quick at the track (totally stock).

I decided to buy a G for a number of reasons last year, but one was to turn it into a streetable, but fun track car. To date I've only changed the suspension on the G: Koni adjustable shocks and Eibach Sportline springs. The Sportline's do drop the car pretty good and give it some natural camber front and back (will be investing in something to get rid of that...currrently rear is at about negative 3 and front is around negative 2). From what I can tell on the street, I've improved the body roll significantly, but expect that there is still some work to do on the suspension (sways and strut brace), although I have severely un-winterized my G with this suspension. Oh, I've also upgraded the brake pads to Carbotech XP8's (used on the WRX and they lasted all day long). I do have the Brembo's and expect that they'll do the job until I'm able to really start pushing the car.

I plan on staying away from power upgrades until I've figured out how the G will handle on the track. My first track day is this weekend with the G, so I should have something to report back afterwards. What should be my next upgrade given the short list of upgrades listed above? I'll be running on the stock wheels & tires (2004 6MT...I know, heavy wheel/tire package), so I know this has to be one of my next upgrades...but cost will prohibit until next year. I probably could have started with a sway bar, and tightened up the car, but I really enjoy the new suspension (look and feel...but more the feel).

I'm quite new to the track, but expect this won't be the last time I go.