2009 Nissan 370Z Automatic - Short Take Road Test

carguyg35

Well one thing to remember is the rear axle ratio for the auto trans car. A lot of times the auto has shorter gears that help it accelerate faster. I don't know what this car has but it sounds logical since this auto trans has one more cog. Or the car could use the same rear axle ratio but use shorter gearing in the auto trans itself for the first few gears. Then usually the auto trans has taller gears in the last few gears. So that could easily explain the quicker times. Also the weather plays some of role in drag times as well.

But for the guys with the manual, you guys bought that to feel connected to the car and really experience the driving pleasure at its fullest. Who cares if the auto is a few tenths quicker?

I just wish C and D spoke to the car more since this model tested was without the sports package. I wonder how it rode and how it handled compared to the SP model. I am not sure what model I want. Now I am thinking base 370z either with 6MT and the SP or base with auto without SP. I have been leaning towards the 6MT with the SP.

Endgame

Aman Carguyg35.

wstar

Here's some raw data on our 6MT vs 7AT gear ratios based on the service manual and simple multiplication:

6MT:
Rear Diff 3.692
1st 3.794
2nd 2.324
3rd 1.624
4th 1.271
5th 1.000
6th 0.794
Rev 3.446

7AT:
Rear Diff 3.357
1st 4.924
2nd 3.194
3rd 2.043
4th 1.412
5th 1.000
6th 0.862
7th 0.772
Rev 3.972

Total gearing, 6MT:
1st 14.007448
2nd 8.580208
3rd 5.995808
4th 4.692532
5th 3.692000
6th 2.931448
Rev 12.722632

Total gearing, 7AT:
1st 16.529868
2nd 10.722258
3rd 6.858351
4th 4.740084
5th 3.357000
6th 2.893734
7th 2.591604
Rev 13.334004

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t-ray

Those numbers are horseshit.

There's no way a 3.7l ~3300lb car with a 3.3 axle ratio is going to trap 108mph in the 1/4. Either that care is making way more power than stock, or the numbers are measuring a *terminal* speed of 108mph, instead of an *average* (over 66 feet) speed of 108mph.

wstar

And here's the "closeness", as percentage change in ratio during each shift:

6MT:
1-2: 38.75%
2-3: 30.12%
3-4: 21.74%
4-5: 21.32%
5-6: 20.60%

7AT:
1-2: 35.13%
2-3: 36.04%
3-4: 30.89%
4-5: 29.18%
5-6: 13.80%
6-7: 10.44%

Those tiny numbers at the end of the 7AT make sense to me. I hardly ever actually use 6th, I tend to double-click back and forth between 7 and 5 because the ratios are so close up there it's almost silly. 7th is the "cruising for best gas mileage" gear, and 5 is the "slight downshift to pass" gear. Starting anywhere under 110-ish or so, I'd drop to 4 (or lower as the case may be) to really accelerate on the highway though.

In any case, in most of the lower gears you'd use on a track, the 6MT's final ratios are definitely closer-geared than the 7AT.

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sensi09

I don't think there's any question that an automatic transmission will yield more consistent straight line acceleration versus the average driver with a manual transmission.

Whether an automatic transmission is simply faster than a manual in general is another question. Other than shift speeds, the power robbing torque converter should be taken into account. Modern automatic transmissions shift very fast and the torque converters are becoming more efficient, but it still takes away some power.

In terms of the an auto versus manual 370Z, well gearing should be taken into account. The automatic is geared more aggressively in the lower gears compared to the manual, so other than shift speed, I think that's where the main advantage is. On a road course however, with an experienced driver, the manual should prove to be the better alternative.

These debates never end though. No need to defend what you drive or what you prefer. For myself, I'll always take a "slower" manual over the dual clutch and automatic transmissions out there.

sensi09

Oh didn't read the entire thread, so missed those couple posts above me. I guess I repeated some of the same things.

TRU370Z

There's only one way to settle this ..........take it to the track! LOL

Forrest

I think most of you are missing the point Lug is trying to make.

1997-2004 Chevrolet Corvette coupe / convertible - Modern Racer - Auto Archive
And then 1999 Chevrolet Corvette Hardtop - Suspension, Handling & Price - First Drive & Road Test Review - Motor Trend
My question is why are we making times same as a c5 vette with 350 hp 360 lb-ft and weighing less th an us?

miguez

Hey Forrest,

It could be down to a lot of different things. For example:

• Suspension geometry, which will determine how the power is transferred from wheels to ground
• Power loss to the drivetrain. Stated horsepower is usually at the flywheel. For that power to make it to the wheels, it needs to go through the drivetrain. This induces losses, and these losses can vary quite a bit between cars, but usually average about 20%. For example, in the 370Z, the stated horsepower at the flywheel is 332. A lot of people have dynoed their cars stock, which will measure horsepower at the wheel (whp) and obtained around 270-280 whp. I am not sure what the C5 had at the wheel.
• Torque curve, not just the overall torque number you see advertised. These can vary dramatically between engines
• Car weight and weight transfer. The more weight on the traction wheels, the more power they can put down before exceeding the traction limit. Weight transfer can also be very different between chassis, and that will alter how much weight is placed on the traction wheels during launch and acceleration

All that being said, it could be none of these, and could be simply down to how the tests were performed, and the differences between these tests.

Lug

Nissan 370Z - 332 HP - 270 ft/lb torque Curb weight - 3232 lbs base
2004 C5 - 350 HP - 375 ft/lb torque Curb weight - 3210 lbs base

Unless it's impossible for a good driver to utilize more than 270 ft/lb of torque and the Vette's extra 105 ft/lb of torque are wasted, there has to be some really good magic fairy dust to get that 4.6 and 13.1 1/4 mile. Forget the 0-60 for a sec, these numbers have a heavier car with 105 less ft/lb of torque and less hp trouncing the vette in the 1/4 mile (the vette is reported at 13.3 to 13.5). This could all well be true and the other numbers we've seen for the auto could be all lies, but I'm still waiting for a reasonable explanation as to why besides "they said so".

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wellarmed

You also might want to consider how much hp the Vette was actually making. Does anyone here think that GM in 1999 wouldn't pump up the numbers to increase sales. GM doesn't exactly have a track record of honesty when it comes to..... well.......anything
In other words......... maybe the Vette wasn't making that much hp and todays Z actually makes as much or more than that Vette really did. Which would explain how in this case, it is possible for the car with the 'lower numbers' to be faster.
Quarter mile and rated hp numbers have always been more important to GM when it comes to selling a American hotrod like the Vette or Camaro. I would question GMs numbers before I would question what came up on the timers when a independent tester ran it at the track.

miguez

Lug,

Without a more in-depth analysis, please consider that the 375 ft/lbs of torque in the C5 may happen in a narrow band of the RPM spectrum. Newer engines are becoming better at delivering a flatter torque curve, which means that their torque is available pretty much off the line. Older engines, or different designs, might only deliver that torque at the end of the RPM spectrum, in which case they might not be as good at the initial acceleration on a 1/4 mile. Since this drag run happens in such a small amount of time, this could incur some of the difference.

Just a possibility.

miguez

It's possible. I have read that Nissan claims the GT-R's engine (new engine design and Nissan's mentality of marketing) will make "at least 480 hp". Top Gear reported that one of the American auto magazines (they don't mention which) benched their GT-R engine and measured 507 hp at the flywheel. Who knows if that's true or not, but an interesting story. Can anyone (MC, maybe you?) corroborate that?

t-ray

The LS1s always made more power than they were officially rated for - so you've got it backwards. GM always underrated the power of the LS1. An LS1 will typically put down 300/300 on a dynojet bone stock. I've seen as high as 300/330, stock. That's a good 35hp, and more than 100 ft-lbs of torque than the z is making, and it's a marginally lighter car to boot.

Unfortunately, people are getting hung up on the 0-60 or the 1/4 ET. Those numbers are believable - they're a function of traction. What doesn't compute to me is the trap speed of 108mph. That's a joke. 105 I believe for the auto, but not 108.