uro279

After reading these posts I have gotten extremely excited about turbocharging my Z.

However, what I understand is that power is not everthing in getting the ultimate performance from a vehicle. Many other things come into play.

One of these is balance. This is one of the Z's strong points and what arguably is what makes the Z such a good combo of power and handling.

This being the case, by adding SC/TT/T, that would obviously change the weight F/B distribution some, but how much would it change the overall 'balance' of the car?

Optimally, I would like the best 'balance' of power and handling so that best times around a road course are limited by me, not the car.

Hope I wasn't too confusing.

Maybe I should have asked this question first but, how is a 'well balanced car' defined?

Thanks.

PS If it were to change the balance, can a ajdustable suspension restore some of this with corner balancing?

dansouliere

Sounds to me like you would be interested in the AEBS Stoker kit.

Sharif@Forged

iTrader: (92)

uro...no need to worry.

As I discovered on the track, the total TT kit only adds a small amount of weight...especially if you ditch the stock cats and get test pipes.

Also, on the track, with that much power, the car has a tendacy to oversteer....very prominently. So adding some weight to the front might actually be a good think for you. I mean..the car wanted to oversteer...mid turn...even part throttle or off throttle.

Most people that get the TT kits dont notice any significant change in how the car handles at part or zero throttle. But carefull with the right foot in the turns......make sure the car is pointed in the proper direction. I had some fun sliding the car around on the track a couple days ago. Drifting at 90mph is insane!!!

uro279

What? Don't understand.

Wait, think I got it. Do you mean because it doesn't add weight to the car but adds more so the weight distribution doesn't change?

uro279

Thanks for the info.. However, if it tends to oversteer more with more power, which is logical, wouldn't you actually want more weight in the back to plant the car more and decrease oversteer?

For example, people who drive in the snow add weight to RWD cars to add traction and decrease oversteer.

dansouliere

Yeah it would be a way of getting big HP without adding any weight.

G35sDriver

Adding weight to the rear may help plant the rear end more, but it also means more weight the car will be swinging around in the rear (centripetal or centerfugal force - cant remeber which one). So it might be good for straight line acceleration but once you start going into a corner you have to deal with the added load.

Sharif@Forged

iTrader: (92)

Exactly...that is what I was refering to.

Think about what happens if you overload the front tires....they loose grip..and you understeer...right?

Also, take a look at the rear engine Porshces...they have all that weight in the back, and they are known for violently oversteering on the track...when under power.

I am certainly no track-god....so anyone else....please jump in and explain some of these principles.

uro279

So with the added weight up front from boost, and with increased power out back, they tend to cancel themselves out somewhat.

Or from a different perspective, if the f/r weight distribution changes from 53/47 to, say 55/45 (just a number), with the increased power out back, during WOT, I would transfer more weight to the rear with the increased power, thereby bringing the distribution back to a neutral stance, and probably even overshooting some to a rear weight bias.

Sound right?

UsafaRice

Ok, you're talking about a few different things here. The added weight up front will increase the understeering effect in a power-off corner because it's asking more of the front tires. The added power increases the oversteering effect when in an on-power corner.

My car weighs under 3,000 pounds right now with a light tank of gas (~2,980). Most of this has come from the middle or rear of the car. I have yet to touch the suspension, but even with really, really sticky tires out back, the car goes sideways with the throttle.

The weight transfer used for acceleration at the dragstrip- straight line, is different than the traction needed powering out of a corner.

uro279

Actually, we're talking about the same exact thing. The example I gave was an extreme one just to simplify the post. Looks like I did the opposite.

I didn't consider the weight factor in over stressing the tires causing loss of traction depending on where the weight is transfered to.

This just goes to show how many variables are involved in maintaining 'balance' and the complexity involved in engineering (ie suspension, brake bias, weight transfer, etc.) the 'best' balance for the masses. That's why the ability to tune according to the application is very important. And this is why adding more power and weight will change the balance which can only be optimized by track time, knowing your driving style, and tuning to achieve the best dynamics for you.

Thanks. I think I'm starting to get it.

Sharif@Forged

iTrader: (92)

OK...lets me put this another way.

Understeering will likely never be a problwm with F/I. Oversteer will be your enemy.

That said..I dont the slightly weight distribution issue will effect everyday driving. The huge increase in power is much more disruptive to the chassis.

BTW, do you guys like me new sig?

I snapped that shot at the track day while my roomate was driving the car. He was doing 130mph in a terrential downpour of rain.

uro279

Cool sig.. Like the torrent.

shiva

The fact is that installing a TT kit and straight pipes will significantly worsen the Z's weight distribution, which is already not good at 53:47. You can certainly kick out the rear end with some throttle, but this is hardly an ideal handling setup. Power oversteer is a band-aid and difficult to control. Non-staggered tires and some good sway bars will help dial out some of the understeer.

But with the Z...you're really fighting an uphill battle, especially with a TT kit. If you're going to be doing a good amount of track duty, I would personally advise against a TT.

Sharif@Forged

iTrader: (92)

Shivak...I think you misunderstoof me. My car has no trace of understeer....it is more like oversteer everywhere. Turn-in, mid turn and exit are all on the verge of massive oversteer.

shiva

What tire setup are you running? It would surprise me if your car was actually set up for oversteer. What is more likely is that you are used to using a certain amount of throttle in corners, and that using that amount of throttle with 400+whp will produce oversteer. But in terms of weight distribution, you must be at around 54-46 now..

Sharif@Forged

iTrader: (92)

I have 255/35/19 and 285/25/19 and this is probably contributing to my oversteer issue. But even corner entry and mid corner (no or very little throttle) is still showing signs of oversteer. The rear just doesnt seem to be very planted.

shiva

Wouldn't a staggered tire setup like that contribute to understeer?

Can an expert chime in on this? What is the cause of GQ's apparent oversteer? The weight distribution of a stock Z is front biased, and he has added a TT kit w/ FMIC and swapped out his cats for straight pipes. He is running a staggered tire setup. Perhaps some setting on your adjustable sway bars or coilovers is causing the rear to slip out?

G35sDriver

Well I think its been pointed out that TT will mos def create loads of oversteer. It's just a factor of how easily can you overpower the rear tires. And with TT, that should be no problem (I would imagine it to be like driving with butter wheels in the rear).

BTW gq_626, your friend is nothing short of insane. As it is I spun out my G in the rain doing 45 mph (spun 3 times and jumped a curb - destroyed axle/hub/wheel/misc. other). I couldn't imagine 130.

shiva

Well sure - that's power oversteer. A car with 65-35 weight distribution could be induced into oversteer with enough power. Regardless, the car inherently has understeer.

GQ is saying that his rear comes loose even with very little to no throttle, which would imply that he inherently has oversteer. I don't know why this would be the case.