2009 Nissan 370Z Automatic - Short Take Road Test

wstar · 04-27-2009, 01:52 PM

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

The 7AT has a wider overall range (lower first gear, higher final gear), but with an extra gear the "closeness" doesn't look too bad, although I didn't run those numbers.

Also, another thing to keep in mind in discussing this, is that the 7AT so far has seemed to have more driveline power loss on the dyno, which is to be expected.

t-ray · 04-27-2009, 01:52 PM

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 · 04-27-2009, 02:02 PM

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.

sensi09 · 04-27-2009, 02:40 PM

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 · 04-27-2009, 02:42 PM

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

TRU370Z · 04-27-2009, 11:49 PM

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

Forrest · 04-28-2009, 01:31 AM

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

1997-2004 Chevrolet Corvette coupe / convertible - Modern Racer - Auto Archive

Quote:

1997-2004 Chevrolet Corvette
Engine : V8, OHV, front engine RWD
Displacement : 5,665 cc
Valve : 16 valves, 2 valves per cylinder
Transmission : 6-spd manual, 4-spd automatic
Fuel economy : city - 18-19 mpg
highway - 25-28 mpg

Suspension : F - Independent upper and lower A-arms
R - Independent upper and lower A-arms
Brakes : F - Vented discs
R - Vented discs

Horsepower : 350 hp @ 5600 rpm
Torque : 360 lb-ft @ 4000 rpm(auto), 375 lb-ft(manual)
Redline : 6000 rpm

Top speed : 175 mph(coupe), 162 mph(convertible)
0-60 mph : 4.9 sec.(manual), 5.3 sec.(auto)
0-¼ mile : 13.6 sec @ 107.3 mph
60-0 braking distance : 125 ft
200 ft skidpad : 0.92 g

Curb Weight : 3210-3246 lbs(coupe), 3214-3248 lbs(convertible)
Overall length : 179.7 in.
Wheelbase : 104.5 in.
Overall Width : 73.6 in.
Height : 47.7 in.(coupe), 47.8 in.(convertible)

And then 1999 Chevrolet Corvette Hardtop - Suspension, Handling & Price - First Drive & Road Test Review - Motor Trend

Quote:

The new-for-1999 Hardtop with its fixed roof makes for an even stiffer structure than its Coupe or Convertible siblings. As our test numbers bore this out, the Hardtop (which comes standard with the race-style Z51 suspension system) whipped through the 600-foot slalom at an average 68.1 mph, the quickest we've gotten out of a C5 Vette. On the other hand, the improved structural rigidity did nothing to enhance straight-line performance. The 0-60-mph time of 4.8 seconds was identical for both cars and the quarter-mile times were actually better for the Coupe (13.2 seconds at 109.6 mph versus 13.3 at 108.6).

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 · 04-28-2009, 07:27 AM

Quote:

Originally Posted by Forrest

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?

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.

wellarmed · 04-28-2009, 08:55 AM

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 · 04-28-2009, 09:18 AM

Quote:

Originally Posted by wellarmed

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.

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?

Lug · 04-28-2009, 09:38 AM

Quote:

Originally Posted by 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.

Quote:

Originally Posted by 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?

If you look at real world dyno results (that vary widely, of course) you will see that the vette averages around 300 hp stock and over 300ft/lb of torque. We haven't seen that on the 370. (more like 260 to 275 hp and significantly less torque). There would have to be some really fancy gearing that no other manufacturer had ever figured out to make up for such a large difference. I can understand how the WRX's and the like do the 0-60 times they get, but these are both rear drive vehicles. The quarter mile numbers are even more far-fetched.

t-ray · 04-28-2009, 09:32 AM

Quote:

Originally Posted by 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.

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.

WUKILLABEEZ78 · 04-28-2009, 01:56 PM

Quote:

Originally Posted by 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?

The C5 corvette is faster than the times you posted from these mags... We're not making the same times, if you go to a corvette forum you'll see what kind of times a stock C5 can really run. The fastest times posted for the 370Z are in the ballpark but not as fast as the corvette

Forrest · 04-28-2009, 02:09 PM

Quote:

Originally Posted by WUKILLABEEZ78

The C5 corvette is faster than the times you posted from these mags... We're not making the same times, if you go to a corvette forum you'll see what kind of times a stock C5 can really run. The fastest times posted for the 370Z are in the ballpark but not as fast as the corvette

i looked at some corvette forums, its hard to tell whos useing a c5 stock or c5 z06.

Like here if you post your times, we want to know how much your underwear weighed so we can figure everything down to the T.

best i cound find so far is this but they still dont clearly mark things.
http://forums.corvetteforum.com/perf...imes-list.html

Quote:

Stock(Street Tire)
12.79x @ 109.80 - boostyfox Details
12.84x @ 111.xx - Ramsiec5 Details
12.98x @ 110.xx - lrbinwpb Details
12.990 @ 107.01 - Mistamike17 Details
12.99x @ 109.81 - c5vette_dallas Details
13.025 @ 105.54 - CRV3TT3 Details
13.10x @ 105.xx - slvrC5vert Details
13.1xx @ 108.xx - CarsRfun's Dad Details
13.1xx @ 106.xx - prwest Details
13.377 @ 104.87 - Roadsho Details
13.401 @ 109.44 - Gideon's_Test Details/Slip
13.465 @ 104.52 - Deathstrike Details
13.637 @ 102.32 - Novicetoo Details

zman1910 · 04-28-2009, 02:53 PM

I don't know what's so hard to believe....

Infiniti G37 sedan 6MT - 0-60 5.2 sec 1/4 mile - 13.9 @ 103mph
Infiniti G37 sedan 7AT - 0-60 5.0 sec 1/4 mile - 13.5 @105.xxmph

Nissan 370Z 6MT - 0-60 4.9 sec 1/4 mile - 13.3 @ 106mph
Nissan 370Z 7AT - 0-60 4.6 sec 1/4 mile - 13.1 @ 108mph

According to mags it seems to fall in line with the same engine in a heavier vehicle. Get over it already.

04-27-2009, 01:52 PM	#1 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3596	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 The 7AT has a wider overall range (lower first gear, higher final gear), but with an extra gear the "closeness" doesn't look too bad, although I didn't run those numbers. Also, another thing to keep in mind in discussing this, is that the 7AT so far has seemed to have more driveline power loss on the dyno, which is to be expected. __________________ 7AT Track Car! Journal thread / Car setup details

04-27-2009, 02:02 PM	#3 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3596	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. __________________ 7AT Track Car! Journal thread / Car setup details Last edited by wstar; 04-27-2009 at 02:06 PM.

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04-27-2009, 01:52 PM	#2 (permalink)
t-ray Base Member Join Date: Apr 2009 Location: bham al Posts: 91 Drives: 05 g sedan 6mt Rep Power: 18	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.

04-27-2009, 02:40 PM	#4 (permalink)
sensi09 Enthusiast Member Join Date: Dec 2008 Location: so cal Posts: 449 Drives: _ Rep Power: 18	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.

04-27-2009, 02:42 PM	#5 (permalink)
sensi09 Enthusiast Member Join Date: Dec 2008 Location: so cal Posts: 449 Drives: _ Rep Power: 18	Oh didn't read the entire thread, so missed those couple posts above me. I guess I repeated some of the same things.

04-27-2009, 11:49 PM	#6 (permalink)
TRU370Z Base Member Join Date: Apr 2009 Location: Dededo, Guam Posts: 42 Drives: 09 370Z MB 6MT Rep Power: 18	There's only one way to settle this ..........take it to the track! LOL

04-28-2009, 08:55 AM	#9 (permalink)
wellarmed Base Member Join Date: Feb 2009 Location: Tucson, Az. Posts: 42 Drives: 09 370Z Rep Power: 18	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.

04-28-2009, 02:53 PM	#15 (permalink)
zman1910 Enthusiast Member Join Date: Nov 2008 Location: FL Posts: 361 Drives: 2011 Audi S4 Rep Power: 430	I don't know what's so hard to believe.... Infiniti G37 sedan 6MT - 0-60 5.2 sec 1/4 mile - 13.9 @ 103mph Infiniti G37 sedan 7AT - 0-60 5.0 sec 1/4 mile - 13.5 @105.xxmph Nissan 370Z 6MT - 0-60 4.9 sec 1/4 mile - 13.3 @ 106mph Nissan 370Z 7AT - 0-60 4.6 sec 1/4 mile - 13.1 @ 108mph According to mags it seems to fall in line with the same engine in a heavier vehicle. Get over it already.