Honda NSX

[Powerslide]

direct injection vee-6, turbocharged, 550hp, nine speed twin clutch gearbox, three electric motors, 4 wheel drive with two electric motors at the front providing torque vectoring. arguably even more technology on it that on a 918 spyder. I've read that early impression are its a bit numb but quick. I find it very interesting

[flmkane]

Why the hell would you need NINE SPEEDS!!!???


Really though, shouldn't modern engines need FEWER gears? I remember F1 V10s tended to have six just because they had sufficient torque. Nine gears is just extra weight.

[Powerslide]

you have a point as turbocharged engine do not rely so much on having too many ratios but somehere wedged between marketing and engineering is to spread as many ratios so that gearshifting and the torque variations between gears differ ever so slightly for that more linear delivery.

adding to your point that it is a hybrid and has three electric motors which should be sufficient to produce enough torque not to do with such a complicated gearbox

[Cold Fussion]

A 9 speed gearbox also means you could have a close ratio 7 speed setup while also having 2 massive overdrives purely so they can claim some amazing economy figure. Are there any decent specifications for the car? A turbo 6 with 3 electric motors with 'only' 570 hp doesn't sound very amazing, would love to see what the power curve of this thing looked liked.

EDIT:
http://nsx.acura.com/specs

Looking at the specifications it does indeed look like it's geared for top speed in 7th with 8th and 9th as two overdrive economy gears. I couldn't find any specifications on the battery pack though.

[SiLo]

The last gears are probably even less than 1:1 ratio.

having more gears means the engine can stay within an optimal powerband more easily.

[Andres125sx]

Why the hell would you need NINE SPEEDS!!!???


Really though, shouldn't modern engines need FEWER gears? I remember F1 V10s tended to have six just because they had sufficient torque. Nine gears is just extra weight.

I´d say... why would you NOT use as many gears as you can if you have a twin clutch?

It improves all the numbers, acceleration, recovery on long gears, fuel efficiency... and if you´re using a twin clutch you don´t even notice any thrust interruption, so what is the problem?

With modern gearboxes if you don´t want to bother switching gears you can put it automatic, so there´s no disadvantages and several advantages

[Tim.Wright]

Turbo engines generally have very wide torque/power curves so extra gears aren't required for powerband reasons.

The current trend is to use the top gear(s) for fuel saving at cruising (i.e. constant) speeds where you don't need the torque for acceleration. The goal being to just balance the aero drag at cruising speeds while making the engine run as slow as possible to mnimise windage and friction power losses.

[Andres125sx]

Turbo engines generally have very wide torque/power curves so extra gears aren't required for powerband reasons.

True, but the key word here is "required"

Electric vehicles don´t require a gearbox, but most of them use it because they improve efficiency. Same here, they´re not required, but numbers are important, specially for marketing, so if you can improve those numbers with some more gear, why not?.

Both acceleration and fuel efficiency numbers improve with more gears, so we could even discuss about the use of the word required here, since this is a flag ship wich is intended to produce the best possible numbers, and to produce the best possible numbers you need the engine running on its very best band as much as possible for accelerating, and as low as possible for fuel efficiency.

Both are achieved with 9 gears, so it´s not required or necessary, but extremely useful

[Tim.Wright]

So tell me then, why didn't they put 20 gears in the NSX?

[Andres125sx]

Probably because with 9 they already achieve the target, keeping the engine on its very best powerband threshold, and at the same time threre´s still some extra gear for fuel efficiency in long runs

Or ask it the other way around, why didn´t they use 4 gears when it does not require any more with a turbocharged hybrid engine?

[Powerslide]

I'm pretty sure the engine in that nsx won't have narrow powerband issue because Honda most likely threw in some sort of v-tec in there, variable vane or twin scroll. 9 speed is overkill. maybe more suitable for a more luxurious car that will be caught wanting for that smooth transition of power. if Honda made a competitor for bmw's m5 with this configuration then it would make much more sense

[mzivtins]

What is the problem with 9 gears when the double clutch system changes gears so fast anyway? It isn't like you are losing anything?

I love this... also the mazda RX9... or RX Vision... both red, both awesome. The world needs cars like these, affordable accessible cars that will hopefully rip the world out of the consumerism of bore with German manufacturers pushing disgusting diesel cars.

[Tommy Cookers]

......With modern gearboxes if you don´t want to bother switching gears you can put it automatic, so there´s no disadvantages and several advantages

does it go into automatic anyway, to prevent stalling in 'manual' 8th or 9th ?
maybe the same even in gears lower than those 2 ?

btw - the B&W type marine diesels will now run 10% power at 7 rpm all day

[Andres125sx]

I don´t get what you mean Tommy. Yes, I guess it will automatically downshift to prevent stalling even in manual mode as all modern gearboxes do, but not sure what you mean with this, that´s standard procedure for every gearbox with any number of gears nowadays

No idea what you mean with the marine diesel engine either

[Just_a_fan]

A common system today is to have the gearbox pull away in 2nd gear by default. If Sport mode is selected then a shorter 1st gear is selected to give, well, a sportier launch. It could be that the gearbox is effectively 6 speeds most of the time with a sprint 1st gear along with long and ultra-long cruise gears for emissions/fuel usage requirements. Most of the time the car would just use 2nd-7th gears.

ZF make a gearbox, the 9HP, that is used by Land Rover (and others presumably). This has a very low 1st gear for towing, off road work etc. and two long top gears for economy/cruising use. Presumably the NSX system utilises the same type of idea (but obviously no towing or off road work).