Thoughts on the 9 speed transmission

[JD Cross]

Been thinking about the 9 speed transmission.
I believe that's more gears than anything else on the market and the Honda engineers must have a reason for so many.

I'm thinking 1st and 2nd will get you to 60 mph and thanks to the DCT it will shift quickly enough not to slow acceleration much.
A manual would probably add a second to the 0-60 time.
I presume 9th would be the highway cruising gear.

If the gas engine is a short stroke lower torque high revving engine like the C30/32 then I'm guessing the rest of the gears would be for torque multiplication allowing the car to keep pulling hard right up to top speed.
This could yield very good performance despite not having super high horsepower

Would be interested in what you think is behind the choice of 9 gears?

 

[BATMANs]

Why can't the new NSX just have a CVT and be done with it?

I was at UC Davis years ago for unrelated business and if memory served me right they were working with Nissan and I think Audi on a CVT that was:

150lbs
can handle 900lbs TQ
Drivetrain loss between 5-9% (they were working on this at the time I was there)
Infinite gears

It was designed for an 18-wheeler.

Now I dunno what happened with the project, but we need this.

It was explained to me that the CVT, coupled with other tech can be the best form of launch control and TCS.

Example would be that if there is any slippage, a computer can simply go "up" to whatever gear ratios to slow or eliminate the slippage without getting off the throttle so that momentum isn't lost.

 

[docjohn]

part of the 9 gear utility is simply gas mileage, the other is a smooth accel curve

 

[Hothonda]

'16 MDX coming out March/April 2015 will be 9 spd DCT

 

[BATMANs]

part of the 9 gear utility is simply gas mileage, the other is a smooth accel curve

why wouldn't the CVT be used for MPGs?

 

[2slow2speed]

Been thinking about the 9 speed transmission.
I believe that's more gears than anything else on the market and the Honda engineers must have a reason for so many.

I'm thinking 1st and 2nd will get you to 60 mph and thanks to the DCT it will shift quickly enough not to slow acceleration much.
A manual would probably add a second to the 0-60 time.
I presume 9th would be the highway cruising gear.

If the gas engine is a short stroke lower torque high revving engine like the C30/32 then I'm guessing the rest of the gears would be for torque multiplication allowing the car to keep pulling hard right up to top speed.
This could yield very good performance despite not having super high horsepower

Would be interested in what you think is behind the choice of 9 gears?

Yep what you are stating makes sense.

When Porsche implemented the 7 speed PDK the lower gears were there to help with acceleration, the 7th gear was there for gas mileage.

On the NSX2.0 the programming of the DCT was probably done in such a way to optimize the engine performance as well as been able to integrate the hybrid motors when in sport mode, and optimize fuel mileage when running in normal mode. So as a car for the road it would offer both performance as well as relative good fuel mileage.

Wouldn't be too surprised if the NSX2.0 is able to achieve sub 3.0 second 0-60 performance.

 

[BATMANs]

....Wouldn't be too surprised if the NSX2.0 is able to achieve sub 3.0 second 0-60 performance.

I don't see any reason why it can't touch under 3.0 secs with AWD.

 

[Valkyrie Pilot]

To be honest, I was really surprised that they went with that. I can't tell if its marketing motivated ("ours goes to eleven") or if its pure performance minded. I believe one of the large car companies (It might have been Fiat/Chrysler) said they determined that adding any gears more than 8 was superfluous. Its like the law of diminishing returns and when you consider the added weight, cost and complexity, vs. the small percentage improvement in acceleration and mileage, it is not really worth it. Also I figure the power plant would be a torque monster down low and if you can keep the turbos from spinning much, it should be pretty good on gas. So wouldn't much of what the 9 Speed is accomplishing already being handled by the engine design?

The fact that the 918/P1/LaFerrari Hypercars were cost no object endeavors that only used a 7 speed, speaks volumes to me.

Then again, Semis have what 16 gears? Not sure if that applies though.

 

[2015 NSX]

That's a lot of paddling! I've got the ZF 8 speed in my DD and paddle shifting down from 8th to 3rd for max decel or accel is kind of excessive...
But, I think it fits the ultra tech character of the car and should help its yet to be released amazing fuel mileage estimates - just hope they got it right!

 

[JD Cross]

I'm wondering if the 9 speed is a clue to something not yet announced, like engine size, or a heavier car weight than expected?
We're all thinking it's a 3.5 L engine but perhaps it's a smaller engine and needs the gears?
Or if the car is heavy, is the gearing needed to help overcome that?

If it's not weight or a small engine are the gears in paired sets like 1/2, 3/4, 5/6, 7/8, 9 and the transmission automatically shifts itself between the gear sets.
The driver selects one of the 5 gear pairs with the paddle and the transmission picks the right gear of the two gear set based on speed, rpm, wheel angle etc?

The choice of a heavier more complex transmission is a bit unHondalike so there must be a reason.

 

[Yinzer]

Why can't the new NSX just have a CVT and be done with it?

Kind of surprised to read that, unless you are trolling for fun? After all the pitchforks and torches that were raised over the NSX 2.0's flappy paddle gearbox, I shudder at the thought of how many stores would be looted and couches set aflame on sidewalks throughout America if the 2.0 came with a CVT.

 

[nsxin425]

With 9-speed, the NSX 2.0 should be in the powerband all the time. I can't wait to see it in person, would love to own one very soon. I was going to buy the 1st gen NSX, but the new NSX changed my mind and so I will work toward the new NSX now. I actually bought some parts for the 1st gen NSX that I think I will sell them since I won't be getting the 1st gen. Although I think the 1st gen is classic, but the new NSX will be leap and bound in technology. Been a lurker here for sometimes, I think this site is awesome!

 

[Glenn Quagmire]

I feel like 20 years from know, the 21-speed will be commonplace...in every driverless car on the road. Those of us that prefer to be at the wheel of our supercars will be viewed as selfish, aging, money-grubbing polluters, who simply don't understand the plight of the average millennial.

 

[2slow2speed]

To be honest, I was really surprised that they went with that. I can't tell if its marketing motivated ("ours goes to eleven") or if its pure performance minded. I believe one of the large car companies (It might have been Fiat/Chrysler) said they determined that adding any gears more than 8 was superfluous. Its like the law of diminishing returns and when you consider the added weight, cost and complexity, vs. the small percentage improvement in acceleration and mileage, it is not really worth it. Also I figure the power plant would be a torque monster down low and if you can keep the turbos from spinning much, it should be pretty good on gas. So wouldn't much of what the 9 Speed is accomplishing already being handled by the engine design?

The fact that the 918/P1/LaFerrari Hypercars were cost no object endeavors that only used a 7 speed, speaks volumes to me.

Then again, Semis have what 16 gears? Not sure if that applies though.

The 918 and the P1 use V8's the LaFerrari uses a V12 so the powerband characteristics might be very different fom what Honda has planned for the NSX2.0.

Just because all of them are hybrids it does not mean that they are designed the same way with the same set of goals as the NSX2.0.

I seriously doubt that gas mileage came into the equation when Porsche/McLaren/Ferrari were designing their cars.

 

[Valkyrie Pilot]

The 918 and the P1 use V8's the LaFerrari uses a V12 so the powerband characteristics might be very different fom what Honda has planned for the NSX2.0.

Just because all of them are hybrids it does not mean that they are designed the same way with the same set of goals as the NSX2.0.

I seriously doubt that gas mileage came into the equation when Porsche/McLaren/Ferrari were designing their cars.

Really? The P1 has a relatively small displacement twin turbocharged engine just like what has been predicted for the NSX. How different could its power band characteristics be?

Not the same set of goals? How would you differentiate the performance and efficiency goals of the 918 from NSX?

 

[2slow2speed]

Really? The P1 has a relatively small displacement twin turbocharged engine just like what has been predicted for the NSX. How different could its power band characteristics be?

Not the same set of goals? How would you differentiate the performance and efficiency goals of the 918 from NSX?

Just because the engine displacement is similar between the P1 and the NSX2.0 it does not automatically mean that they will have similar power output curves.

I hope you realize that factors such as bore/stroke, shape of the intake/exhaust ports, intake exhaust valve timing, engine timing, compression, materials used in the piston/con-rods/crankshaft/engine construction can affect how the engine performs. For forced induction engines there are many other factors as well.

A well designed V8 engine with the same displacement as a well designed V6 engine will rev at a faster rate given that there are 2 more combustion chambers, even considering the parasitic loses that those 2 extra cylinders would create. There are other factors that affect volumetric efficiency as well in regards on how the air flows in and out of the combustion chamber at a given RPM.

In regards to the goals of the Porsche 918 vs the NSX2.0, the naturally aspirated 4.6L V8 gasoline itself produces 600+ HP, and has a redline in the 9K+ vs a 3.XL FI engine with unknown HP and redline. Which engine do you think will be more stressed?, which engine do you think has more exotic components? Which engine was made to meet Euro 6 regulations from the get go?

If you take a 10,000 foot view the performance/efficiency goals might look similar, but if you look closer they are clearly different given that the 918 and the NSX2.0 were made to meet different standards (standards in this case, include performance, price point, emissions, mpg, etc, etc)

 

[krea.tion]

Given that shift speed is anything greater than zero, the benefit that number of gears has on acceleration will look like this with number of gears on the x axis and acceleration on the y axis. The question I suppose is how many gears to achieve MAX.

 

[JD Cross]

Given that shift speed is anything greater than zero, the benefit that number of gears has on acceleration will look like this with number of gears on the x axis and acceleration on the y axis. The question I suppose is how many gears to achieve MAX.

Could you explain a bit more about the curve and what mode, median, and mean represent?

 

[krea.tion]

Could you explain a bit more about the curve and what mode, median, and mean represent?

I can try! Please ignore the "mode median mean", I was simply trying to find a graph that was skewed to the right and thats what google gave me. Place "acceleration" on the Y-Axis. The Y could represent how fast the car accelerates from a stand still to its hypothetical top speed. On the X-axis you have the "number of gears in the gearbox". Traditionally, there was generally an increase in acceleration performance when more gear ratios were added, hence why cars used to have 3-speeds then 4 then 5 then 6, etc (this is represented by the rising part of the curve). But there comes a point (and someone mentioned this earlier) where the addition of one more gear does not give you increased acceleration potential because adding gears has diminishing returns (represented by the maximum point in the graph). Imagine if the tradition 6-sp gearbox suddenly had 100 speeds. While, hypothetically, the engine speed would stay within its peak powerband more often, the amount of downtime due to shifting gears would make the whole system incredibly inefficient. While modern day DCT minimize shift speed, there is still a small amount of downtime between shifts. Given that the new NSX came out with a dual-clutch transmission with an infinite number of gears, the car would have zero acceleration potential (represented by the curve in the graph approaching zero as X-axis (number of gears) increase). Given modern day power and torque curves, I kind of guesstimated that the point at which maximum acceleration can be achieved would be somewhere around 7-speeds which begs the question, is 9 better than 8? Is 8 even better than 7? Or perhaps 1 to 7 are performance gears and BOTH 8 and 9 are meant as cruising gears only. It would take a lot more data to accurately find the exact maximum point but thats how the graph would look.

 

[JD Cross]

Krea.tion
Thank you, I understand better now.
If 7 gears is the norm in performance cars at the moment perhaps the top two gears are for mileage/cruising as you surmise.
The coming months should shed more light on the choice of 9 gears.

 

[Aluminsx]

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[krea.tion]

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LMAO. Remember a time not too long ago when people were saying the same thing about 4 blades. Now they act as if 4 blades is the fucking norm and you're only a true man if you go with the penta-blade.

 

[jwmelvin]

It is possible, is it not, that a dual-clutch transmission has continuous torque transfer through a shift notwithstanding that the shift takes some finite time? Crudely speaking, engage the new gear then disengage the old one. It may be that nobody does this because of clutch-life issues, but it's not clear to me that there has to be a period of no torque transferred through the transmission as with a single-clutch transmission.

 

[krea.tion]

It is possible, is it not, that a dual-clutch transmission has continuous torque transfer through a shift notwithstanding that the shift takes some finite time? Crudely speaking, engage the new gear then disengage the old one. It may be that nobody does this because of clutch-life issues, but it's not clear to me that there has to be a period of no torque transferred through the transmission as with a single-clutch transmission.

Currently... No. Even the best of the best: PDK, Ferrari, GT-R, etc all have some downtime between shifts. I'm not saying its impossible but we haven't quite seen it yet. If absolute 100% timeless shifts is something the NSX could do, it would be GROUNDBREAKING.

 

[areout]

9th for highway cruising? If they stick with all this hybrid greenery I wouldn't be surprised if top 2 or even 3 gears are meant for cruising more than for acceleration...