Can somone please explain the power graph?

[P3nT4gR4m]

I've had a search about the forum and, although this thing gets a lot of mention, no one seems to have spelled it out in small words for idiots like me.

It probably doesnt help that my screen isn't HD and I cant actually make out the legends for the orange and green lines but, even then I'm not sure I'd be much the wiser.

I do notice the graph changes when I change some of the settings but is there a rule I should be applying? How do I tell if it looks good or bad?

 

[NLxAROSA]

The graph tells you how much torque you have at a certain RPM (orange) and how much horsepower you have at a certain RPM (green). It will help you to determine gear settings and optimum shifting times.

 

[the Interceptor]

The power graph shows you horsepower and torque of the engine for the respective revolutions, such as this one does:

What is good and what is bad depends on what you want your car to do. What you should pay attention to is the torque curve (the dotted line here), cause it shows you where the engine provides actual force, and where it doesn't. For example, some turbos lose torque at top revs, so you might want to gear the car appropriately or raise the power in quick tuning. If you want as much power as possible, raise the power addition to the max, but note that the engine characteristics will get edgy. If you don't need absolute power and want balanced characteristics, you should try to get a balanced torque curve, maybe with a bit more at the top end, similar to the one above.

 

[mindwise]

Hi Pentagram,

I'm probably rehashing what you already know.

The orange is torque and the green one is horsepower (vertical)
The horizontal bar is the rpm's (Note: the RPM on the powerbar go higher then the ones on the gearing-bar.)

So these two will tell you how much torque/power you have at any given RPM.
The flatter the lines, the more evenly the power is distributed along the rpm band. (where a turbo would typically suddenly give more power after a certain rpm.( more like a 'bell curve' then a line.).

I aim to have the lines as horizontal as possible, but i don't know if that's correct

the philosophy: if my engine has a lot of power -ONLY- in the red of the rpm's, i'll be lagging in the low rpm.
if it has less power but that power is more evenly distributed from low to high
rpm, my average 'available power' is higher, and so i should be quicker, or so goes my hypotheses

Looking forward to more insight and possible corrections,

Rgds

 

[NLxAROSA]

the philosophy: if my engine has a lot of power -ONLY- in the red of the rpm's, i'll be lagging in the low rpm.

Which is not necessarily a problem, as long as you keep the engine at high RPM. This will ofcourse influence the way you should shift gears. It is wise however to make sure that gear shifting doesn't drop you back in RPM too much.

Take my Viper SRT10 Coupe for instance, it has an almost flat line for torque. Meaning: you have maximum torque along a wide band of RPM. It really doesn't matter if you shift a bit late or early, there's always plenty of torque available.

 

[the Interceptor]

Here's a nice comparison to show the differences between an N/A engine and a turbo:

The red curves represent the torque (lower curve) and the power (higher curve) of the standard Nissan 350Z. The blue curves represent the same car with a turbo setup, again with the torque as the lower curve and the power as the higher curve. Note that the N/A version gives you much less peak torque, but a much more balanced curve. That means that it will work cleanly throughout the entire rev range, while the turbo will give you the famous "kick" at mid revs, but will run out of steam at the top end. So depending on what you plan to do with your car, you either want to balance torque to make it drivable or to gather torque at the top end to give you maximum speed, but less driveability. Additionally, you should pay attention to what kind of engine you're looking at (turbo, supercharged, N/A).

 

[nd 4 holden spd]

And to flog a dead horse, you should tune to have a wide and fat torque curve. i.e. You want a fairly flat torque curve, a torque is what makes you accelerate. Power is a by-product of torque and RPM, and is more a placebo than a figure to rely on (Power is good for top speed but I'm unaware how that works, torque gets you to that top speed). More torque through more RPM is what you want. Also consider that with a torque curve extending to high RPM (flat torque curve) power will get bigger and bigger as a result.

 

[Famine]

And then you want to ignore all of that, because the engine does exactly squat - the wheels are what drive the car and, after all the power has gone through the drivetrain and been reduced by up to a quarter (in extreme cases) and the torque has been multiplied up by the gearbox, what you have at the wheels may bear no relation at all to what you had in the engine.


Though the basic shape of the graph will be the same, just with wildly different numbers, so the relevance of a flat torque curve and where the power peak arrives is not diluted.

 

[the Interceptor]

Power is a by-product of torque and RPM, and is more a placebo than a figure to rely on (Power is good for top speed but I'm unaware how that works, torque gets you to that top speed).

I think the good old "power is good for top speed" saying does go well with the idea of torque. If you have a lot of horsepower, you will have quite a lot of torque at high revs. Therefore, your top speed will be pretty good, because arriving at high revs in top gear, you will still have a significant amount of force available.

And then you want to ignore all of that, because the engine does exactly squat - the wheels are what drive the car and, after all the power has gone through the drivetrain and been reduced by up to a quarter (in extreme cases) and the torque has been multiplied up by the gearbox, what you have at the wheels may bear no relation at all to what you had in the engine.

But shouldn't you adjust your gear ratios according to the torque curve of the engine?

 

[Famine]

Ah, I was referring to reality (a mistake, I know. There's bees out there!) and standard cars. In GT, where you can adjust gear ratios by 0.001 at a time, yes.

 

[the Interceptor]

But in reality, knowing the torque graph of my car has definitely helped me to understand what to expect where and to drive accordingly. And the actual torque available can be clearly felt accelerating through a gear.

 

[Famine]

But in reality, knowing the torque graph of my car has definitely helped me to understand what to expect where and to drive accordingly. And the actual torque available can be clearly felt accelerating through a gear.

Though the basic shape of the graph will be the same, just with wildly different numbers, so the relevance of a flat torque curve and where the power peak arrives is not diluted.

Point is if your dyno says you've got 200lbft of torque at 3,500rpm, you've actually got 1,800lbft because you're in second gear. Or 740lbft, because you're in 5th.


The curves are still the same (more or less) - you still get peak torque at the same place, and that noticeable drop-off at 6,800rpm - but the numbers on the dyno aren't really relevant to anything. On standard cars in reality.

 

[nd 4 holden spd]

And then you want to ignore all of that, because the engine does exactly squat - the wheels are what drive the car and, after all the power has gone through the drivetrain and been reduced by up to a quarter (in extreme cases) and the torque has been multiplied up by the gearbox, what you have at the wheels may bear no relation at all to what you had in the engine.


Though the basic shape of the graph will be the same, just with wildly different numbers, so the relevance of a flat torque curve and where the power peak arrives is not diluted.

So how does what you said mean what I said should be ignored? What I said still applies, but you're going into gear tuning now, and as far as adjusting the power and torque curve for best results goes (which is what he is asking) you do that at the engine. You can tune gears or shift accordingly to keep it the fat of the torque, and shorter gears yes (as I know you know, but for other's makes) sends more torque to the wheels.(Not always a good thing, acceleration or drive is what you ask yourself here).

I think the good old "power is good for top speed" saying does go well with the idea of torque. If you have a lot of horsepower, you will have quite a lot of torque at high revs. Therefore, your top speed will be pretty good, because arriving at high revs in top gear, you will still have a significant amount of force available.

Of course. Don't know why I didn't realise that. Or maybe I did and then forgot, still a on my behalf.

 

[the Interceptor]

Point is if your dyno says you've got 200lbft of torque at 3,500rpm, you've actually got 1,800lbft because you're in second gear. Or 740lbft, because you're in 5th.

The curves are still the same (more or less) - you still get peak torque at the same place, and that noticeable drop-off at 6,800rpm - but the numbers on the dyno aren't really relevant to anything. On standard cars in reality.

You're absolutely correct, but then again I ask myself why you brought this up. Everybody was talking about the shape of torque curves before, and not about absolute numbers.

Of course. Don't know why I didn't realise that. Or maybe I did and then forgot, still a on my behalf.

Don't worry, if I remember correctly it took me something like 3 years to realize that simple fact.

 

[Famine]

You're absolutely correct, but then again I ask myself why you brought this up. Everybody was talking about the shape of torque curves before, and not about absolute numbers.

More knowledge = better understanding.

Incidentally, the (wheel) power required to travel at a given speed (in mph) is [(weight in pounds/0.0135)+(Cd x Frontal area in square feet x 0.00256 x speed x speed)] x speed/375 - since someone was asking.


And power is the rate of torque conversion - 1 horsepower is 550lbft per second. Torque is just the force, power is how it works. And this post is one of the best explanations you're likely to find about the differences between the two and their application.

 

[Ravenmaven]

I do notice the graph changes when I change some of the settings but is there a rule I should be applying? How do I tell if it looks good or bad?

The rule I apply to my engine tuning is finding the most efficient hp to torque ratio. You'll notice that when you lower the hp number that the drop in torque values is signifigantly less than the hp values (look at the actual numbers...you have to zoom in) thus only slightly reduced torque vs. signifigantly reduced hp. The result is extra PP which can be used to reduce weight or add downforce into the equation.

 

[mindwise]

the wheels are what drive the car and, after all the power has gone through the drivetrain and been reduced by up to a quarter (in extreme cases) and the torque has been multiplied up by the gearbox, what you have at the wheels may bear no relation at all to what you had in the engine.

Though the basic shape of the graph will be the same, just with wildly different numbers, so the relevance of a flat torque curve and where the power peak arrives is not diluted.

Hi Famine i can see what you say, yet i'm mystified by your comment.

Doesn't more power and a flatter curve still indicate you'll get more power on the wheels?
I mean 1/4 of 200 is still more then 1/4 of 180 right?
There should still be a relation with what you have in the engine, if there is no power at the engine or a lot, will have bearing on what you can get on the wheels.

I'd say (and i'm going to read the post you refer us too, so expect some edits in this premature post.) the following:

If the engine does not have any torque, you'll never get any on the wheels.
The total ammount of power the engine can disperse over the width of the gearing is like calculating the surface of the powercurve.

A flat curve maxing at 300nm can easily have more 'surface' then a (very) curvy one that maxes at 340nm.
As the 'backend' of the engine is the same, (same car, only changing the engine characteristics) we should be able to determine a setting where the engine has maximum (theoretical) potential. (which is what we are discussing here right).

@arosa, i think that is exactly what i said, i think you quoted only half of the remark i made
====
Okay, diving into the post you mentioned now, i hope i can read and edit my post faster then you are able to correct me. (i like the RTFM saying )

Edit: read the other post.

Complex material indeed it seems, though the story was clear it's quite unclear to me on how to proceed and try get the maximum potential.
It seems all we can do is fiddle with three components:
- Tyre choice (only 750 PP, but we don't know how much traction they can produce)
- Downforce: Ofcourse lowering downforce has 3 effects
-- less grip especially in fast corners.
-- less drag so faster on the straights (though i expected the difference in straight speed to be more dramatic).
-- More PP that can be added to the engine (or tyres or less weight).
- Weight of the car. (the calulation in scaffs post will allow us to determine if in theory we should get more acceleration but what the effect on cornering will be, is enigmatic (is that a word?).

I want telemetry like PC F1 games have, and until that time:

I can't tell you tuning guys how happy i am you offer to try and sort it out for lost guys like me

 

[the Interceptor]

And this post is one of the best explanations you're likely to find about the differences between the two and their application.

That is an excellent explanation, though I personally find the torque way of showing how things work the easier one to grasp. Still, 👍

 

[nd 4 holden spd]

More knowledge = better understanding.

Incidentally, the (wheel) power required to travel at a given speed (in mph) is [(weight in pounds/0.0135)+(Cd x Frontal area in square feet x 0.00256 x speed x speed)] x speed/375 - since someone was asking.


And power is the rate of torque conversion - 1 horsepower is 550lbft per second. Torque is just the force, power is how it works. And this post is one of the best explanations you're likely to find about the differences between the two and their application.

So when the engine is spinning faster it converts more torque/second. Then say with different cars you have to decide what will be better, 555lbft/second, or 650lbft/1.2sec kind of thing? Bit of simple maths there.

 

[Venari]

Yep, reducing your laptimes is all about power.

You want to design your shift points such that the amount of tramisitted power is maximised at all times, as the quoted gtp article says.

Also, for more information: http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm

What is basically says that if you take two cars which weigh the same and fit two different engines... your engine which produces 200lbft peak at 3,000rpm and maximum 150hp at about 6,000rpm, and my engine, which produces 150lbft and 200hp at 7,000rpm... my car is going to be faster.*

The flipside is that your car will be easier to drive to the shops.




(This of course is true anyway for the follwoing reason: it doesn't matter how much power or torque you've got - my car will always be faster. )

 

[nd 4 holden spd]

No, the one with more torque will win assuming the same gears and similarly shaped torque curves. Torque is for go, power is for show.

 

[the Interceptor]

I found another graph which, although not related to Gran Turismo, shows nicely what's going on. It's a comparison of the standard engine setup and an upgraded version of the Audi 1.8 TT:

As I said, I find torque easier to understand, so let's stick to the right graph, showing the torque curves before (blue) and after (red) tuning. While applying quick tuning in Prologue, you may have noticed that the power and torque curves mainly change on the upper end of the curves (at high revs). So the result of tuning a car in the game is similar to what this upgrade kit archieves: more torque (= more power) at the upper end of the rev range.

Sounds good so far, but this bears a potential problem. You know that accelerating a car means you rev through a gear, then change to next gear, and so on. That means that going through the gears, you're wandering over this torque curve. Now, it's obvious that you want to use the range between 4500 and 6500 revs, because it has the highest torque. So what you need to do is adjust the gearing so that shifting up, your car won't drop below 4500 revs. Additionally, you won't want to let the revs drop below that taking a bend, simply because you will drop off the boost and suddenly have no more power available.

Now, imagine driving the car with stock setup. You'll immediately understand that you're facing none of those problems, as the engine is widely usable between 2200 and 6000 revs. You obviously have less overall power, but the engine easily becomes much more usable and forgiving.

So what does that mean for Prologue? Well, if you tune a car to work well on a standard track like Suzuka, you should aim for a flat torque curve, giving you a flexible engine with a large usable rev range (I usually like a bit more torque at the top end, makes the car feel more agile when revving). If a maximum top speed is what you want, and you know that you won't drop below a certain number of revs in the gear you'll be in (like on Daytona), you can maximize the power output and thus gain a good top speed. You just need to be aware that if you don't gear the car appropriately and / or drop off the sweet spot at any time, you will face a significant power loss.

 

[nd 4 holden spd]

I found another graph which, although not related to Gran Turismo, shows nicely what's going on. It's a comparison of the standard engine setup and an upgraded version of the Audi 1.8 TT:

As I said, I find torque easier to understand, so let's stick to the right graph, showing the torque curves before (blue) and after (red) tuning. While applying quick tuning in Prologue, you may have noticed that the power and torque curves mainly change on the upper end of the curves (at high revs). So the result of tuning a car in the game is similar to what this upgrade kit archieves: more torque (= more power) at the upper end of the rev range.

Sounds good so far, but this bears a potential problem. You know that accelerating a car means you rev through a gear, then change to next gear, and so on. That means that going through the gears, you're wandering over this torque curve. Now, it's obvious that you want to use the range between 4500 and 6500 revs, because it has the highest torque. So what you need to do is adjust the gearing so that shifting up, your car won't drop below 4500 revs. Additionally, you won't want to let the revs drop below that taking a bend, simply because you will drop off the boost and suddenly have no more power available.

Now, imagine driving the car with stock setup. You'll immediately understand that you're facing none of those problems, as the engine is widely usable between 2200 and 6000 revs. You obviously have less overall power, but the engine easily becomes much more usable and forgiving.

So what does that mean for Prologue? Well, if you tune a car to work well on a standard track like Suzuka, you should aim for a flat torque curve, giving you a flexible engine with a large usable rev range. If a maximum top speed is what you want, and you know that you won't drop below a certain number of revs (like on Daytona), you can maximize the power output and thus gain a good top speed. You just need to be aware that if you don't gear the car appropriately and / or drop off the sweet spot at any time, you will face a significant power loss.

Yes, you can sacrifce bottom end torque for high end torque. You want a steady flow of torque through the rev range for racing though. And the way GT5 protrays tuning isn't true either. You can build bottom end and top end at the same time, it's not always a give and take situation like they make out.

 

[Parnelli Bone]

They brought back the full power/torque graphs? 👍 Aww man, i gotta get this game soon.

 

[BonzoHarry]

They brought back the full power/torque graphs? 👍 Aww man, i gotta get this game soon.

Yea, but they're WORTHLESS graphs.

-So I hit peak power 'around' 9000rpm, so where is the line that indicates 9000rpm? In front of 9000, in the middle of 9000, or at the end?

-I hit vvtli somewhere in the middle, around 6k-ish...but where exactly? I need to adjust my gearing accordingly.

-I need to shift some place after peak power, so once I discover where peak power is, I need to set my gearing so that the power I make when I shift to 4th will be greater than the power I am currently making in 3rd.

 

[the Interceptor]

You're right, the power graphs as they currently are are pretty useless. They show you more of a direction you're heading at with tuning, but no precise figures. I always wondered why they never brought back the detailed graphs we had in GT1. You even could change the boost of turbos and see how the power and torque change.

 

[nd 4 holden spd]

I'm pretty confident that your 9000rpm is the right hand side wall of the graph. Notice 0rpm is the left hand side? If that 0 was in the middle or right hand side then the car would be capable of negative rpm. Also, that figure they use for max rpm seems to be the rev limiter on most cars, so it can't rev higher. I agree the graphs are useless for exact figures though. I'm glad that in the chase view the little "bar" showing revs is actually labelled now with the revs you're pulling.

 

[VentureDenny]

I'm pretty confident that your 9000rpm is the right hand side wall of the graph. Notice 0rpm is the left hand side? If that 0 was in the middle or right hand side then the car would be capable of negative rpm. Also, that figure they use for max rpm seems to be the rev limiter on most cars, so it can't rev higher. I agree the graphs are useless for exact figures though. I'm glad that in the chase view the little "bar" showing revs is actually labelled now with the revs you're pulling.

There is one relationship between HP Vs. Torque that will help you interpret the graph...
The torque curve will always intersect the HP curve at exactly 5252rpm., (theoretically IRL, but I'm not sure about GT5P graphs). You can use that intersection to make an informed guess as to what RPM's the peaks actually are. Since the graphs don't show exact RPM's.

 

[Parnelli Bone]

Yea, but they're WORTHLESS graphs.

-So I hit peak power 'around' 9000rpm, so where is the line that indicates 9000rpm? In front of 9000, in the middle of 9000, or at the end?

-I hit vvtli somewhere in the middle, around 6k-ish...but where exactly? I need to adjust my gearing accordingly.

-I need to shift some place after peak power, so once I discover where peak power is, I need to set my gearing so that the power I make when I shift to 4th will be greater than the power I am currently making in 3rd.

Wow. You're right. Where the hell is the GRID fer crissakes? How come they got power graphs looking so good (and accurate) in gT1 and 2, but left them out entirely in GT3, and made them half-assed (no grid, vague indications of where power and torque are) in GT4???

 

[twintsupra]

I found another graph which, although not related to Gran Turismo, shows nicely what's going on. It's a comparison of the standard engine setup and an upgraded version of the Audi 1.8 TT:

All these graphs are wrong, horsepower and torque ALWAYS cross each other at 5252 rpm.