Top Speeds in Different Gears (6MT)
 

I just thought it would be interesting to see what the car could achieve in each gear. All of this was done at the 7500 rpm red line and not past it even though I'm sure the electronic nannies would let you squeeze out a little more if you wanted to.

1st - 40

2nd - 65

3rd - 90

4th - 115

Is it normal for the progression to be this linear? That would lead me to believe it could get 165 without a limiter. Of course all of this was and should be done in a safe and controlled environment. Also, I was impressed to see that it could nail sixty reasonably comfortably while still in second. That definitely helps it 0 - 60 times for the crowd that judges almost solely on that statistic.

Loving this thing!:driving:

1: 41
2: 67
3: 95
4: 122
5: 155
6: 195

Resistance from the air will flatten those numbers as speed increases in 5th and 6th. The Z has nice drag coefficient spec, nonetheless physics will take over eventually.

Anyone on the forum taken one to max velocity on the track? And isn't the limiter set at 156mph?

im kinda curious what the gear speeds look like in the 7AT, anyone got em?

In for updates.

Not exactly. Air resistance does not affect a car's theoretical top speed in any gear. The top speed in any gear is only a function of engine speed, gearing and final drive (and wheel size I suppose). This is all assuming the car has the power to reach those speeds.

PeterSellers, that explanation sounds right to me. I have to doubt the z will do 195 as JoeD stated. Unless it's modified and a new transmission which makes this thread very unspecific.

would love to know this too

Exactly.

+1, though, aerodynamics do play a HUGE part in it.

Take a Mustang GT500 and a Corvette. Mustang will throw all it's power into pushing air over what is basically a brick with wheels, vs the Corvette slipping through the air somewhat like a wing. End result, Corvette is faster.

195 MPH is the theoretically calculated top-speed based on gearing, tire-size, and the engine's redline. Not taking into account the tire's expansion at that speed, 7500 RPM in 6th-gear works out to 195 MPH.

I never said the car will get to that speed.

But a TechnoSquare re-flash with an 8100 RPM fuel-cut will get you to 210 MPH in 6th at that RPM. :tup:

Not sure I agree aerodynamics has anything to do with that..

If a car make 155 mph @ 7.5k in 6th gear for instance, it will make that much speed at that gear whether on the moon, on earth, or on a dyno. Air resistance will only affect the time for it to get there, assuming it does.

^ nope ... not on the moon ... gravity is different => your tire size is effectively less as less mass = less contact patch

it's the same mass on the moon, it's the weight that's different ;)

I was assuming constant wheel diameter though since I was looking at the aerodynamics perspective

Wrong. Moon has no air to resist. Dyno has no wind resistance. On the moon, the car would go as fast as it can barring friction losses with the brakes, drivetrain, front wheels, bearings, etc (provided it could breathe), and rolling losses (ie, tires). On a dyno, it'd go nearly to the theoretical limit, the difference being the same as on the moon, except without the front brakes/wheels being factors. Of course, I'm discounting gravity effect and lack of air for the moon.


So, let my try again:

You're driving along at 75MPH, 0MPH headwind. Your car is using (example) 65HP to perform this work.

You're driving along at 75MPH, 20MPH headwind. Your car is using 65+N HP now, because there is more resistance.

(You can change these numbers to driving at 75, with a 75 mph tailwind vs 75 with a 0mph wind)


Same effect applies when attempting to determine the maximum speed fo the vehicle. The faster you go, the more resistance is applied to the front of the vehicle.

As you increase speed, you increase air resistance. Lower drag coefficient means the car slips/cuts through the air more instead of creating turbulence which distorts the air, making it more resistant.

Imagine a biplane wing on a F18. It wouldn't got as fast...ever, given all things being equal.

Actually, the moon has no atmosphere, so the Z won't reach any speed in excess of 0, unless you modify it to accept oxygen from a solid state oxidizing agent

Physics FTW. Air resistance is a force. Any force that acts upon an object will cause it to accelerate. In this particular case, air resistance does actually slow the car down. The faster the car goes, the greater the force against the car. Without friction/air resistance/restrictive forces, anything with a force acting upon it will accelerate infinitely. [sigma]F=ma (net force=mass x acceleration) With one force and a constant mass, something would accelerate forever to an infinite speed.

Exactly. Arguments about a car on a moon are a wee bit ridiculous, but as are most tangents.

Actually technically that's old school newtonian physics. In modern physics, relativity applies. What you said is true at lower speeds. However, as speed approaches the speed of light, newtonian physics ceases to be accurate and relativistic physics takes over. The energy required to accelerate an object of mass to speeds approaching the speed of light approaches infinity. An object with mass can never achieve the speed of light. Only an object with zero mass (i.e. a photon) can travel at the speed of light. And so far, there is no evidence that any object regardless of mass can travel faster than the speed of light. So infinite speed is a theoretical impossibility, at least according to what scientists think.

Not to mention that the moon has a very rough bumpy surface, so even if you get the z to move, you will be leaving bits of undercarriage, exhaust, suspension, etc.... all over the place

Seems like I recently saw a video like that...

Maybe a set of snow tires for the moon sand?

lol

Ha yes you are true!
I was trying to sort of keep it in the realm of the car. And yeah, by infinity, I mean the speed limit of the universe: speed of light. I completely agree with you, I was just trying to keep this applicable to the Z, which, as badass as it is, won't get to the speed of light. Haha! :tup:

Wrong again, you're arguing a different point than I am

What I'm trying to say

If you're @ 4k rpm on 4th doing say 100mph, you will do that irrespective of any other forces, for the rear wheels to do 100mph, your engine has to be at 4k rpm if in 4th, it's how the car's gearing has been setup. Air resistance aka drag force only affects how much TQ you'll need to get there i.e how much time I'll take you to get there, but once you're there, you will be doing 100 @ 4k rpm.

Take it easy guys I only said on the moon because I wanted to use the 0 air resistance factor, of course the cars won't move there lol

Ha, I knew the 7AT was faster!

(ducks)


Also, it looks like we should be dyno'ing the car in 5th gear?

OK, that makes sense...I guess I was going from the point of real-world, not theoreticals...then again, at what point does the Z run out of juice...

My limited Physics knowledge says that at a certain point, the car will not be able to accellerate any further as the wind resistance will be too great, so it will never see the 7500 redline in 6th. It will just sit on a lower rpm and be unable to push through the wind given it's known HP output.

More power and torque will change this.


I've been saying this all along on other threads. The only problem with using 5th is running into the speed limit of the rollers on the dyno. Some dyno's only support 200km/h, so using 4th is the only option to keep the speed down. (shoud only vary by a few kW anyway.)

my 2c

What's interesting is that using 4th, unless compensated for in some way, the 7AT will show higher torque numbers (and therefore higher HP) due to the reduced ratio in the rear end and 4th gear.

Hmm...interesting, but, not that it matters much. Comparative gains is what I'm interested in, which before and after dyno runs is good enough. :)

0-60 by 2nd Gear?
 

Is this possible with either transmission? I'm asking about stock of course.

Thanks!

For the manual tranny yes, not sure about the auto

The auto takes you to somewhere between 55 & 57. However, once you hit it into 3rd you blow right by 60 almost instantaneously and are threatening 100 before you know it.

I can get to 60+ mph in 2nd.

Manual you can get to ~67 mph in second.

The 7at tops out around 54mph in second.

Its been discussed before at length.

http://www.the370z.com/nissan-370z-g...gears-6mt.html

:iagree:

by the time i notice the shift and look down its at 80 :)