hey guys, im preparing to build my car for weekend road racing and i was looking in the shop builds thread and examing people dyno curve's and more importantly horsepower vs speed spread sheets. what is the average speed you guys who road car usually find yourself at. (I KNOW SPEED IS DEPENDENT ON THE TRACK LAYOUT ITSELF.)but im asking this general question to find out how important TORQUE is in lower rpm ranges. thanks in advance

 

like you said....depends on the track.

 

which kind of road racing? are you talking about HPDE or time attack / bumper to bumper racing?
the Z in the stock form has enough low to midrange torque to come out of most of the corners pretty quick but lacks high rpm power to keep up in the straights (especially with the DE or REVUP engines).

the kind of events you're going to attend, the level of preparation you want to put in the car, the amount of money you want to spend in the car to be faster, the kind of tires you're going to run are all information necessary to tell WHERE you'll need more power.

for example... you said road racing but it's HPDE...
I'd say you invest as much as you can in brakes, suspensions, differential, lightest wheel and stickiest tires... and while you're doing those works remove a couple of hundreds lbs from the car and call it a day.

if you think as road racing as koni challenge or time attack is a different story.

but if it's like I think it is (HPDE)... the engine is the LAST part you do want to touch to go fast around the track.
you need to improve those departments first:

1) DRIVER. is the most important to be fast. period. an excellent driver on a Z can beat a mediocre driver on pretty much any car of the planet. (even on an enzo or fxx.. because a mediocre driver on those car will probably kill himself at the second turn)

2) tires and wheels. get the stickiest you can... there you get the most of your cornering speed, braking and ability to put the power on the ground.

3) racing seats, 4/5/6 point harness and a roll bar/cage/whatever... if you focus on keeping yourself in the seat and spend your effort to do it you aren't focusing on driving.

4) suspension arms for adjustment. you need to maximize your tires contact patch on the ground. and on R compounds going from 1 degrees of negative camber upfront to 3 and over makes miracles in terms of lateral grip.

5) differential and suspension (shocks/springs/swaybars)
you don't want that inside rear wheel to spin and burn your tires coming out of a corner but you want that smoke converted in speed.. than, once you find out how your car is going to change attitude (more understeer mainly) you'll pick the suspension to make it neutral again.

6) remove weight... the power itself mean nothing... the power to weight ratio is important... and removing weight is cheaper than adding power.
for example... 3300lbs/270whp = 12.2 lbs per whp
but 3100lbs/270whp = 11.5.
to achieve the same ratio on a stock weight you need 287whp...

7) when all of this is done... you can focus on where you want the torque.
hint.. on a 350z you want to improve the mid to high end power.

 

I'll wait to post my rant until the OP answers the "what exactly do you mean by road racing" question

But in reality, the average speed question really is moot. For track driving (not necessarily racing, not necessarily HPDE) you want the WIDEST powerband possible, you want a motor that emphasizes USABLE power and torque across the widest RPM range possible (anywhere from 2000 to 8000 RPM, in ANY gear). You want to avoid peakiness ... you want the emphasis on longevity over absolute power.

Of course, even this is subject to many factors

 

I am picturing you waiting for an answer...then pouncing like a tiger playing with it's food.

 

sorry, I started with a preemptive rant

 

 

It would seem to me that a road racer, SCCA for example, would have experience in different cars on different courses.

 

sorry guys but what i mean by road racing is primarily time attack. i know suspension setup is key its just that since i got a GREAT DEAL on a turbo kit, i would like to know how to BETTER not best (if there is?lol) setup my torque curve then my power curve.

 

Time Attack ... uugh ... must ... resist ... urge to ...

Time Attack has rules and classes just like everything else. Before spending the time/effort/money installing that turbo kit, do your research on what class you'd be competing in with whatever group it is. Most mods like that will put you into an unlimited category, and unless you plan on doing everything else mentioned above along WITH your turbos, you'll end up more frustrated than you could have ever imagined.

And that's assuming you've even got the experience to USE any mods you put on the car

 

Got ya. Pick a club. Go racing with the car as is. Familiarize yourself with club rules and classes. Then you can better make decisions about forced-induction.

 

Sell the turbo kit you got such a deal on and use the money here:

http://www.skipbarber.com
http://www.bondurant.com
http://www.jimrussellusa.com

 

The turbo kit in the Time Attacks will likely place you out of a competitive category. The 350Z is quite agile in N/A form. Put the money towards good suspension mods.

 

FIXED!

 

As many have said. Invest in the driver first and foremost. Once that has been done for a while, decide where and what you want to run. Read the rules very closely, and then build the car according to those and your driving style. At this point I wouldn't believe you have a style yet, or at least one that would be competitive.

Click the links above, drive a few HPDE's, then decide the direction you want to go.

 

let me add something here...
regardless of the rules, DON'T go for power until you can manage the car as it is.
power, if used in the right way, just helps to hide bad driving habits and driving glitches.
go out.. have few hpde... at a certain point you'll see that your lap times will become consistent... and unless you're an unreal natural talent, your lap times will be slower than more experienced people, on the same car.
that is the right time to invest money in the driving school. ( IMHO )

than go back, check your lap times and see how much you improved... and repeat until you're in the fastest hpde group... after some experience go back for a more advanced driving class...

at that point you should have enough experience and "track maturity" to know what you need on your car to be faster.

and by the way... tracking a twin turbo car could become quite expensive pretty fast...
if you blown a competition shock probably you'll need to spend 1K to replace it or rebuild...
if you blown a twin turbo engine the bill is going to be a little more steeper and probably you won't be any faster than the "full grip" car.

 

thanks for the good advice. i hear yal on the whole experience thing, becuase ive autocross'd several times and done a rew test and tunes to prove my driving when the car was 100% bone stock. its just that, like everyone, we all want to go boost, i just happen to like to road race/time too so i want to setup my power forband that while im already goin boost and get some GENERAL POINTERS FROM YOU ALL. so come weekends when i got some free time i can be ready to go to the track (powerband wise, i know suspension and driver skills are key). ya feel me?????

 

Actually, yes I do. I remember when I first started on a race track and though power was it. My 1966 Pontiac GTO made about 430 hp and weighed in around 2,700 lbs. For a long time I couldn't figure out how guys making less horsepower in a heavier car were beating me in the 1/4 mile. I was the noob that everyone made fun of at OCIR.

I finally spent some time researching it and learned about grip, reaction time, and getting ALL the power down. Without adding any power to the car I dropped a second in the 1/4 mile with just practice and some training. Adding suspension took off another second and added consistency. After 6 months of work I started winning my class every now and then and earned a lot of respect from the old timers.

You're on that same curve right now. Once you get past the horsepower obsession and focus on skill and handling you'll start going faster and earning some respect from your competitors.

 

Sounds like you'll do just fine at the time attack events

 

I have been autocrossing for over 4 years. I like power, but "adding power" has yet to make it to the top of my to-do list.