[Z33Fairlady]

Hi all,

I have a question regarding Power (kilowatts) and Torque (Nm).

When it comes to a drag against another performance car, should we be more concerned with the cars torque output or power output.

Putting aside power to weight ratio, some cars have more torque output than the Z33 (with less power) whilst other cars have more power (with less torque or similar torque).

What is also interesting is that the delivery of turbocharged vehicles is always greater than naturally aspirated vehicles. For example, the STi/EVO with similar power and torque figures and yet, their acceleration capabilities and times tell a positively differently story.

Common sense would say that a car with more power and more torque than the Z would be quicker, both from standing start and overtaking.

Thanks,
Z33Fairlady

 

[nang3]

i think torque has a fair bit to do with it in terms of in gear acceleration, not sure about standing starts..
I know my F6 (270kw, 550nm, 1800kgs) feels and im sure IS, a lot faster than my Z... some of this could be contributed to the rush of the boost building, but in real world terms i.e. 80kph dropping back a gear etc, nothing has come close to keeping up yet, when in my Z a lot of cars would..
I cant imagine what some of the edited F6's and XR6T's with 900+nm would feel like !!

 

[mchapman]

Power = Torque x Rpm / 5250

 

[Domino]

ive always understood power to be area under a dyno graph

peak power tells you nothing, take an S2000 for example. Sure at some insanely high rpm it makes 170kw, but catch it in the low revs and an Excel will give it a go

on the road torque rules, thats what u feel pull you along

if u want to see what big torque numbers feel like, drive one of the supercharged 5.5L AMGs, the pull is phenomal, any gear, any rpm, it just makes u laugh how effortless it gains speed

 

[nang3]

... or an AMG SL65... 1000nm **drooooollll**

 

[db350z]

or an Bugatti Veyron ... 1001hp **drooooollll** LOL

 

[davidm]

If you're in an optimal gear, then the power is what will make all the difference. Good example is the S2000 as Tpiace mentioned - it's barely slower than the 350Z in terms of 'full bore' acceleration ... if anything I'd say the 2 cars would be very similar.

On the other hand if you're talking abvout acceleration in the 'wrong' gear, or at the 'wrong' revs (which is the same thing), then torque will tell you who is quicker.

One of the best examples is an F1 car - ~900kW and ~400Nm of Torque. Nothing accelerates like an F1 car, and there are a lot of cars with more torque.

So in summary, if you have a car that has a lot of torque, but no revs then it does not have much power and hence will not accelerate quickly (ie. a Trunk). On the other hand car that has little torque, but can spin like crazy and retain the torque figures at those revs will have a lot of power, and accelerate quickly if you're in the 'right' gear.

Best of both worlds is an engine that has a lot of torque, and spins like crazy (and retain the torque at high revs). This car will be very quick in every situation. ie. Any Ferrari, Galardo, or e46 M3.

ps. Look up any acceleration figures and compare them to power-to-weight and torque-to-power. You'll see some relation between acceleration and weight-to-power, but no relation at all between acceleration and torque-to-power. That is because acceleration times in maganizes are always clocked in 'optimum' gear.

For example, the STi/EVO with similar power and torque figures and yet, their acceleration capabilities and times tell a positively differently story.

Neither car accelerates any quicker than 350Z. Though, what they do is launch much better than the Zed and hence the great looking figures. Though, look at any of their 'clocked' figures and compare them to the Zed from 40/60kph onwards and you'll see that there's nothing between them. The acceleration numbers 'look' better than Zed's due to the 4WD, and not the turbo.

ps. I have lined up both '02 STi and EVO8 to confirm that.

 

[scathing]

When it comes to a drag against another performance car, should we be more concerned with the cars torque output or power output.

Putting aside power to weight ratio, some cars have more torque output than the Z33 (with less power) whilst other cars have more power (with less torque or similar torque).

What is also interesting is that the delivery of turbocharged vehicles is always greater than naturally aspirated vehicles. For example, the STi/EVO with similar power and torque figures and yet, their acceleration capabilities and times tell a positively differently story.

For a straight out drag you should be more concerned with power. In a drag race you can get the car into its power band and keep it there, so midrange isn't as important. On the track, where you might need to fall out of your top third of the rev range when you corner, having more midrange torque to pull you through the corner is just as important as power in the top end to punch you down the straight.

I've seen the dyno graphs for some drag Silvias where the engine's power curve is almost flat until 6500RPM...and then the power spikes in that last 1000RPM to make around 300rwkW. Its bloody quick down the strip, but would be useless anywhere else.


And your comments about the "delivery of turbocharged vehicles" isn't exactly right. The Evo and STi make just as much power as the Z (if not more, the Evo is pretty much always underrated to get under Japan's old 206kW agreement), but weigh less. And 4WD grip always gives you a better launch if you're willing to be savage with it.

But the main thing is the gearing. The Evo and STi tend to run really short gearing, which is great for acceleration but bad for top speed. With the right gearing and a fast enough gearbox, I could make an otherwise stock Hyundai Excel beat a GT-R to 60km/hr......but it would have a top speed of 100km/hr.

 

[ky350]

Nang3 - 550Nm from the Phoon is not to be messed with when its on the move!!!! Its the same for those 700 - 1000Nm AMG Mercs.

DavidM - nice explanation. I wonder how the Z would fare in rolling starts against the newer 06 STi's with 400Nm on board? Have you come across any 80 - 120km/h figures yet?
BTW, I read your little letter too - if someone was to spot discrepancies between data and graphs, it would be you LOL.

 

[drenvy]

This is some good info, keep it up. Look I rekon the more power you make the more torque (dont know how accruate this is lol) but I figure if you do performance mods to increase the power on your Z it will also bump up your torque.

 

[ky350]

This is some good info, keep it up. Look I rekon the more power you make the more torque (dont know how accruate this is lol) but I figure if you do performance mods to increase the power on your Z it will also bump up your torque.

More power does not necessarily mean more torque for a NA engine. For example, you could buy headers for the Z which will increase the power at the top end of the rev range, but may decrease power and hence torque in the mid range. This would consequently also effect the street drivability of the car, with reduced pull when in a higher gear ie 4th @ 40km/h.

Also, DavidM pointed something out to me and other members of this forum a while ago about torque that I have never forgotten. As a rule of thumb, and engine making 100+Nm of torque per litre of engine capacity is a very efficient engine. The 2003 Z makes almost 104Nm/L and it also maintains high torque throughout the rev range, which is why it can pull so well when doing lowe speeds in higher gears. A while ago I went through the back of motor mag an calulated the Nm/L of all the hi-performance street cars available today. From memory, the M3 hade the highest torque/L at approx 114Nm/L, beating all Ferrari's and Porsche's.

So if you want to increase the torque of the Z while keeping it NA, it can be done but don't expect massive gains in torque. After all, even Nissan with all its financial resources had to reduce the max torque of the 35th / 06 Z engine, when chasing a higher power output with a higher rev ceiling.

 

[Domino]

the loss of 10Nm on the 05/06 is due to the shorter intake runners

i was very suprised at how much torque i gained in the low revs by fitting the high-flow cats (also possibly due to the exhaust as well). It pulls so hard from as little as 2000rpm in 2nd now, so much so that turning a corner will light up the rears in 2nd from anything above 2000rpm. When stock, ud need at least 4000rpm showing on the dial to get any considerable pull from the Ann engine in 2nd

but when dragging that extra torque is useless, because when shifting at high rpm, that revs will fall back above 5000rpm anyway. So when running WOT power rules, on the street torque rules

 

[scathing]

Depends on how much money you want to spend.

If you get a stroker kit, you'll get more torque and possibly lose revs from your redline. But you should make more power, or you can do other stuff which will keep your redline and make more power in total.

 

[davidm]

ook I rekon the more power you make the more torque (dont know how accruate this is lol)

As others have mentioned, that is usualy not the case ... unless you have a Turbo/Super-charger. With an N/A engine it is hard to make more torque, but in order to make more power you just need to 'retain' the torque that you make right now, but higher in the rev-range.

Let's put it this way, 350Z makes 363Nm @ 4800rpm and makes 206kW at 6200rpm. That means that it makes ~315Nm at 6,200rpm. Now if you could tune it so that it makes 363Nm at 6,600rpm then you've got yourself ~250kW (at 6,600rpm) ... and even more if you could rev the engine higher.

To gain power with an N/A engine one could 'optimize' the torque figure, but there's rarely more than 10% to gain even if you don't have an engine with such good torque figures as the Zed. With the Zed you would think that even 5% gain in terms of torque peak would be hard to reach. On the other hand in terms of power sky is the limit.

 

[scathing]

Its hard to make torque gains without changing displacement. If you have a look at NA motors of a certain displacement, their peak torque figures are usually pretty close.


The thing is, torque is a measure of how strong each "bang" is in your motor. Obviously the greater the displacement, the more fuel and air and thus the stronger bang.

Power is a multiple of that "bang" strength, and the number of times it happens in a certain period. So NA motors make more power by piling on the revs, since torque is near-static for displacement. All you can do is try designing your engine as efficiently as possible, so your torque doesn't fall away too much in the top end.


FI makes a lot of torque, because by running more boost you can always force more air into your smaller displacement.....giving an effectively higher displacement.

 

[Lemanz]

or an Bugatti Veyron ... 1001hp **drooooollll** LOL

haha yun, nice pic :clap: very nice with the ink T-wing!!

yeah i think the torque giving you more power in the lower rpm where the turbo charge vehicle with the smaller cc engine give more on the high rev.

for example 350z 3.5cc engine and GTR 2.6cc twin turbo

Can notice the 350z for the line quicker if both not launch, but when both engine rev to around 3000rpm, 350z feel flat and GTR feel the turbo kick in and go and catch up.

But if both can launch in the drag, i m very sure the turbo charged car will be quicker.

cheers
Gary

 

[nang3]

Nang3 - 550Nm from the Phoon is not to be messed with when its on the move!!!! Its the same for those 700 - 1000Nm AMG Mercs.

DavidM - nice explanation. I wonder how the Z would fare in rolling starts against the newer 06 STi's with 400Nm on board? Have you come across any 80 - 120km/h figures yet?
BTW, I read your little letter too - if someone was to spot discrepancies between data and graphs, it would be you LOL.

oh yeh i love that feeling of 550nm pushing me along... makes overtaking so easy its a joke !!!
im getting my f6 edited in january sometime so hopefully will have around 750nm for a while until i get injectors/bigger cat/dump pipe and custom tune.. im aiming for around 320rwkw and 850-900nm

 

[ky350]

Nang3 - not sure if you have the manual or auto box, but either way, I hope that it can hold up to 750Nm, let alone 900Nm!!!!!
I read that the original BA auto box was good for 550Nm and the newer 6 speed auto is good for 600Nm - still a long way short of your goal.

 

[nang3]

yeh ive got the manual, always been a manual driver...

most of the big power cars are manuals and dont seem to be having any problems, apart from a bit of clutch slippage, but almost a newton kilometre of torque will do that hehehe

 

[Domino]

the Euros build sportscars with alot more power and their manual 'boxes are super smooth

its just because Ford (and Holden) persist with a really old cheap manual gearbox