370Z 7 Speed Auto Review

JoeyD

I promised a review of the 7 Speed Auto. Lets start with the bad news.

The Dyno.
I've attached an overlay of the Dyno pulls I did this weekend. The best number we could get was 269. That equates to about a 22% drive-train loss as compared to the 6spd manuals 15-16%. However, if you look closely you will see that the graph ends at about 6,500RPM. For some reason the engine was not allowed to rev over 6,500 (the ABLS?) and in some cases much lower RPM. I would like someone else with an auto to get on a dyno and see if they have the same result. This will make tuning almost impossible. This 6.5 limit DOES NOT occur when all 4 wheels are turning...on the street.

Now for the good news.

M-mode shifting.
M-mode shifting is everything it should be. The computer only takes shifting away from you at the very bottom of the RPM range; just enough to keep the engine from stalling.

On the way up the gears shifting with either the stick or the paddle works great. It WILL NOT MAKE A SHIFT FOR YOU. What else can I say about the shifting? For once the M-mode auto works the way it should.

I think I've noticed a difference between the paddles and the stick. It seems that paddles shift faster than stick. It's even more noticeable on the way down the gears.

The throttle blips for down shift rev-matching are AWESOME. It's like music.

When I first started driving I thought the 1-2 and 2-3 shifts where too soft. Since then it feels like they have tightened up considerably and now a max RPM shift can snap my head back. Overall I would say the shifting in M-mode is firm and sporty and the shifting in D-mode soft and predictable.

The power transmission feels great all the way to red line, in spite of what the dyno says. I don't feel like 332 is an underestimate of power. My guess is if the 370Z 7 Speed auto were allowed to rev to red-line it would make every bit as much power as the 6 Speed.

Back a little further though my lack of a Limited Slip is really showing. It's hard to get much traction at all coming out of turns at speed. Definitely need a limited slip.

Feel free to ask any questions about the auto if I missed anything.

Attached Images

370z_dyno.jpg (115.5 KB, 154 views)

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When was the last time you did 230MPH in something with 4 seats?

Crash

According to that dyno, the AT is losing more power than I thought it would. Any thoughts on this?

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2002 Corvette Z06 - Totaled
2003 Corvette Z06 50th Anniversary

ssqpolo

didnt injected pull at 258 stock?

Crash

I think that was on a mustang dyno.

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2002 Corvette Z06 - Totaled
2003 Corvette Z06 50th Anniversary

azn370z

does the car rev beyond 6500 rpm on the street?

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2010 k23
H&R sport springs / Spc rear camber arms / SSR SP1 / Berk cbe / Varis cf lip / Nismo S-Tune side skirts

Ryan@IP

We saw 258-261whp stock. But that was on a Dyno Dynamics when the car had 499 miles on it. We typically see Dynojet numbers come out to be ~12% higher than our dyno.

But as I'm sure many other people will reiterate, there's no "good" way to compare two dyno charts on different days, different dynos, etc etc. Ideally, we need to see a 6MT and 7AT back to back at the same place.

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Lug

I don't think you can make a determination at all until we understand why it can't rev over 6500 because it hasn't achieved max HP at that RPM yet. Do you see this limitation on the street as well?

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JoeyD

It revs all the way to red-line on the street. There are only two possible reasons that it won't rev beyond 6,500. Either the ABLS is grabbing it or, the guy sitting in the car was afraid to push to 7,500. Either way on the street it drives perfect.

__________________
When was the last time you did 230MPH in something with 4 seats?

JoeyD

I think the power loss you are seeing is 100% the 6,500 rpm problem. I would guess that if I could have rev'd to 7.5 the result would of been about 280-285 but, that is just an interpolation of the graph we have.

__________________
When was the last time you did 230MPH in something with 4 seats?

Lug

Probably be a good idea to look at what similar dyno's on the manuals show at 6500.

edit: looking at some of the Dyno charts in the Forced Induction section, the base lines look around 8 to 10 HP down at 6500 rpm compared to 7500. That would suggest your's would be 275 to 280 HP if your dyno pull went out to 7500 rpm.

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keep Chubbs in your pocket - Chubbs

Endgame

^I am sure you are correct...

370ZDreamer

Agreed, if you look at your chart at 6,000 and compare it to the baseline in this thread here: Berk Technology HFCs gain +19whp + 18wtq! you are within a few horsepower of the manual transmission car in the thread. That would lead me to believe the difference isnt that much. We really need a clean dyno pull to be sure though.

SoCal 370Z

Thanks for doing this dyno—rep points dynoed your way!

Crash

Agreed to all. The 6500RPM would definitely be the problem, but of course, we'd STILL need the pulls to be done on the same dyno machine and on the same day as the the MT pulls to see for sure.

However, my guess was that the AT would only be about 7HP less than the MT (due to the new type of torque converter) and I'm still confident in that number. I look forward to the real results.

__________________
2002 Corvette Z06 - Totaled
2003 Corvette Z06 50th Anniversary

sbkim

Great info thanks.

Would like to see how this power + 7AT translates to track times.