Top Speeds in Different Gears (6MT)

[schnabdt]

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!

[JoeD]

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

[370Zsteve]

Originally Posted by schnabdt

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!

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?

[Red370]

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

[Zeto]

In for updates.

[PeterSellers]

Originally Posted by 370Zsteve

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.

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.

[schnabdt]

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.

[chuckd05]

Originally Posted by Red370

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

would love to know this too

[JoeD]

Originally Posted by PeterSellers

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.

Exactly.

[kannibul]

Originally Posted by PeterSellers

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.

+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.

[JoeD]

Originally Posted by schnabdt

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.

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.

[G37Sam]

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.

[shabarivas]

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

[G37Sam]

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

[kannibul]

Originally Posted by G37Sam

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.

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.