-kg or +HP, which is more valuable?

[MetalheadA7X]

Less power and less weight is good on a twisty track compared to more weight and more power - which is the whole point of this thread, its a choice between the two.

Sorry my bad.


Less weight every time

 

[panjandrum]

Well, I also nearly always drive with the cars lightened as much as possible and then work with the power.

BUT, there is a problem with this: A lighter car may allow you to pass more easily through the corners, while a more powerful car may allow you to pass more easily on the straights. The issue is that it is inherently more difficult and riskier to pass in corners than on straights. Often you can get stuck behind a car which is slower through the corners. Even if your car is faster, if the driver does not mess up you often won't get a chance to pass in the bends. For example, your car may hold the bends better, but not *enough* better to hold the outside line and still pass. Or, you'll get past but then be easily overtaken by a faster car down the straights. Therefore, your best bet might be a power/weight ratio which allows you to gain on the straights, but only hold your own through the bends.

So, although I usually race with my cars as light as possible because I enjoy the way the cars drive more that way, I often find I can increase my chance of winning by adding power before adding lightness.

 

[youaredie]

I try to think of it in this way. Cars which are known for their weight, like the ford gt, I will lower the power and lower the weight. Cars which are already generally light, like the S2000, I'll add some weight but also add power.

It's more of compensating for the shortfall of every different car.

 

[VetteDawg]

Well, I also nearly always drive with the cars lightened as much as possible and then work with the power.

BUT, there is a problem with this: A lighter car may allow you to pass more easily through the corners, while a more powerful car may allow you to pass more easily on the straights. The issue is that it is inherently more difficult and riskier to pass in corners than on straights. Often you can get stuck behind a car which is slower through the corners. Even if your car is faster, if the driver does not mess up you often won't get a chance to pass in the bends. For example, your car may hold the bends better, but not *enough* better to hold the outside line and still pass. Or, you'll get past but then be easily overtaken by a faster car down the straights. Therefore, your best bet might be a power/weight ratio which allows you to gain on the straights, but only hold your own through the bends.

So, although I usually race with my cars as light as possible because I enjoy the way the cars drive more that way, I often find I can increase my chance of winning by adding power before adding lightness.

I usually don't like to copy someone's ENTIRE post (and I hate it when people do that) but IMO this entire post makes a lot of sence. I typically don't run the weight all the way down unelss the car just has ooddles of power...for many of the reasons stated by panjandrum.

....I also agree with youaredie...

 

[semilife]

Better to lose weight better acceleration etc.

 

[TN2004S4]

weight=failed

 

[nissman]

Always lose the weight!!

 

[Rudi Raser]

the S2000 Amuse with S2/S2 - 650PP is faster with more weight.

but mostly less kg is better.

 

[kekke2000]

I always strip the weight and go for R tyres. Especially if there is a lot of corners.

 

[WolfRacer543]

The laws of physics will however dictate that an 1800 kilo car will be more difficulty to start turning and more difficulty to stop turning that an 1100 kilo car.

Weight always blunt ability when it comes to a cars ability to turn.

And for anyone that wants the physics....

http://phors.locost7.info/phors13.htm


Regards

Scaff

The other important "physics" issue with heavier cars is that tires become less efficient the more weight (load) you put on them. You'd normally expect frictional force (the side force allowing you to corner) to double if you double the weight of the car, because F = mu*N where mu is coefficient of friction and N is the normal load. But in reality, tires dont have a constant coefficient of friction, it decreases the more you load up the tire, so if you double the weight of the car, you get less than double the potential cornering force. Thats because the law that says F = mu*N doesn't take into account tires are elastic.

So you have 2 major effects of weight, one is the transient effects because of an increased moment of inertia, and the other is tires become less efficient. That's without considering CG height, which effects how much weight is transferred. Moment of inertia is actually mass at a distance, so it doesn't immediately follow that a heavier car will have a slower transient, if you removed the weight from close to the centre of the car (say, the gearbox), it will have little effect, but if you remove it from far away (like the doors) it'll have a larger effect.

 

[clerk]

Weight is a force. You need to remove mass from a car. Which yeilds a smaller weight force and blah blah blah you understand

 

[WolfRacer543]

Weight is a force. You need to remove mass from a car. Which yeilds a smaller weight force and blah blah blah you understand

Its all about the tires

 

[888 Tuning]

Soooo.... has anyone actually done a test ?

Should be rather simple..

 

[Stevisiov]

Weight is a force. You need to remove mass from a car. Which yeilds a smaller weight force and blah blah blah you understand

Yes that's right, if we want to get all technical, weight is a good thing as it increases the reaction force between the ground and your tyres, giving us more grip. Unfortunately the only way we can increase weight on earth (to a large extent) is to increase mass, which has fairly big performance disadvantages all over the board.

If we could increase gravity, then our car would perform better from its increased weight, yet it wouldn't have the drawbacks of added mass.

I think I will stop rambling now.

 

[TiZzla]

It depends on the track/car

At suzuka its always better to have less weight because of all the corners.

But at Daytona road its important to have lots of power for the straights.

But over all i think weight is more important. because less weight makes you faster in a straight line AND corners, Power makes you faster in a straight line only.....

 

[clacksman]

If we could increase gravity, then our car would perform better from its increased weight, yet it wouldn't have the drawbacks of added mass.

I think you may have just invented downforce. 💡

👍

 

[niky]

Soooo.... has anyone actually done a test ?

Should be rather simple..

We "test" every time we tune a car for the online challenges...

There's a wide zone where wildly different hp-weight-tire combinations will give you similar fastest lap times... usually, I make my choice based on what's easiest to drive at 99% over 5 to 10 laps... even if it's not outright the fastest.

With online lag, bumping, grinding and the potluck of starting positions, a consistent car is often better than a fast one.

 

[tdk]

"More HP makes you faster on the straights. Less weight makes you faster everywhere."

...end of discussion really. horsepower for top speed, less weight for less top speed but arguably better acceleration and DEFINITELY better handling.

 

[Hugo Boss]

...end of discussion really. horsepower for top speed, less weight for less top speed but arguably better acceleration and DEFINITELY better handling.

Not really. Generally the statement "More HP makes you faster on the straights. Less weight makes you faster everywhere" is true. However, it can be the case that you gain time on the straights that can't be made up in the corners. A few examples where more HP is/might be the better choice:

-Cars that struggle with finding traction (like the mentioned 650PP Amuse S2000 on S2 tyres) may perform better with more weight.
-The Elises go a lot faster around Suzuka with maximum power than with minimum weight.
-During cupracing, a few extra HP could help to make the overtaking a bit easier. The laptimes will suffer slightly, but your chances to finish higher will increase.
-If you have troubles keeping the car on the track, more weight could improve your consistancy and thus your overall performance in a race.

It's always worth trying to play a bit with the kg/hp variables 👍

 

[Stevisiov]

I think you may have just invented downforce. 💡

👍

Well that's about the best substitute we have, but it's not perfect as downforce usually comes at the expense of more drag.

We "test" every time we tune a car for the online challenges...

There's a wide zone where wildly different hp-weight-tire combinations will give you similar fastest lap times... usually, I make my choice based on what's easiest to drive at 99% over 5 to 10 laps... even if it's not outright the fastest.

With online lag, bumping, grinding and the potluck of starting positions, a consistent car is often better than a fast one.

+1

...end of discussion really. horsepower for top speed, less weight for less top speed but arguably better acceleration and DEFINITELY better handling.

While its decent simplification, the increased horsepower also increases acceleration, or rather, the increased torque, which increases the cars horsepower increases acceleration. This increase can be fairly substantial on some cars, yet others, the torque increase doesn't seem to do much for acceleration as the torque is all in the high rev range.

Like most things to do tuning and racing cars, many people think you need this thing and not so much of the other (the torque vs Horsepower argument is a good example), this is not normally the case. In racing its all about finding the best balance, so in answer to the thread title, neither. Both are equally important, what's more important is knowing how much of each you need for each individual track.

 

[WolfRacer543]

...end of discussion really. horsepower for top speed, less weight for less top speed but arguably better acceleration and DEFINITELY better handling.

Actually in real life (can't speak for every car in GT5P) many cars wont have a noticable handling improvement by decreasing weight.

It depends whether the weight reduction...

1. Reduces moment of inertia, which improves transients (mass removed from close to the centre of the car wont significantly alter moment of inertia). Though it makes transients sharper, which generally makes handling better, but again depends on the car, driver, track, etc.

2. Reduces centre of gravity height. This will improve geometric weight transfer. (weight removed from low down may actually raise the CG height and make geometric weight transfer worse).

3. Improves the tire efficiency. This is what improves your steady state corning, such as a long sweeper, if tire efficiency doesn't change, a heavier car will go just as fast through a sweeper (I can't think of any time reducing weight would make tire efficiency WORSE, except maybe if the tires are designed for a much much heavier car than they're actually on, but there are times when tire efficiency will stay the same regardless of weight).

If a reduction in weight doesn't benefit those 3 things, then you wont see an improvement from weight reduction. In fact, I've seen an open wheeler race car which actually takes long sweepers FASTER with a HEAVIER driver (but transients are worse). Its simply because of where the driver is in the car relative to the centre of the car, centre of gravity height, and the fact tire efficiency is not effected by weight because the car is already extremely light.

 

[Stevisiov]

Well you could simplify that to say: If you remove weight from the wrong place, you can upset the balance of the car, making it handling worse as a result.

Perhaps 'worse' would have to be clarified though.

Generally you would remove as much weight as you could from a car as long as you don't upset the balance, the improvements to acceleration and deceleration are usually very noticeable.

 

[LittleBahamut]

This is quite a good thread!

One thing that got me darn confused is when some are saying to add weight to some of the cars. I thought adding weight was generally a bad thing in racing cars. Do you add in certain spots of the car to get a better weight distribution? Or is there something else I missed about adding weight?

I happened to stumble upon a time trial video here that really questions everything I possibly did wrong. Maybe its the reason why I am having a hard time getting 1st place in the 750PP races of the top license?

http://www.youtube.com/watch?v=0uF3uZ1Dn7c

You can see from the info, that it appears to keep the same weight but added lots of HP. I am amazed by how this person have the car skid through these corners fast. The last time I remember doing this track with an R35 with 750PP, I know I was not going this fast.

I have been reducing weight on that Suzuka track and that video alone just confuses me.

 

[Rage Racer]

These settings should be balanced, but power will be more valuable at Daytona Speedway (IMO). In an 800PP speedway race, a Lotus Elise with 800 performance points can't competite a Ford GT with even 750 PP value (I have seen an Elise 111R in this event when I entered it on a GT LM Spec II ).

 

[niky]

You add weight when the car doesn't have enough power. The Elise is the perfect example of how "power-to-weight" ratios are less important than "power... period" in high speed acceleration. An Elise's (or Exige's) power-to-weight ratio may give it terrific cornering and corner-exit, but it runs out of puff down the straights.

 

[888 Tuning]

We "test" every time we tune a car for the online challenges...

There's a wide zone where wildly different hp-weight-tire combinations will give you similar fastest lap times... usually, I make my choice based on what's easiest to drive at 99% over 5 to 10 laps... even if it's not outright the fastest.

With online lag, bumping, grinding and the potluck of starting positions, a consistent car is often better than a fast one.

I have tuned one or two cars myself so I understand what you are saying... but what I meant was we have 3 pages of discussion about whats more important in this game... yet no one has performed a controlled test to determine the answer. Until you do this, we are just bantering (which I quite enjoy) but I prefer fact.

Unless someone else beats me to it I will do some testing and post the results... its my wedding anniversary tonight so I'll cancel my dinner appointment and fire up GT and spend the night infront of the TV doing tests. I'll need to wear some earphones to drown out the noise of the wife... but this should also provide me many many more nights by myself in the near future

But seriously....

Take 3 cars 1 small 1 medium 1 large (doesnt really matter which cars, cause that will start an argument within itself! )

3 tracks Eiger; Suzuka; Daytona Oval

3 laps:
1st lap with the car in standard tune
2nd lap with the PP kept identical, but weight shed and power decreased
3rd lap with PP kept identical but weight added and power added
No other tuning to be performed.

Feel free to contribute... even if you just take 1 car to 1 track and do the above 3 laps. (Use Arcade/ Quick Race/ which allows you to Tune your car. At the start, pull over and let all other AI cars through and disappear so no slip streaming... use this lap as a sighting lap, next lap as your hot lap)

Post your results
Car:
Track:
Lap1 Time(Standard):
Lap2 Time(less weight):
Lap3 Time(more weight):

 

[Stevisiov]

This is quite a good thread!

One thing that got me darn confused is when some are saying to add weight to some of the cars. I thought adding weight was generally a bad thing in racing cars. Do you add in certain spots of the car to get a better weight distribution? Or is there something else I missed about adding weight?

I think you may referring to me hear, so I think I should clarify what I said. What I was saying, is if you could add weight without adding mass, it would be very beneficial to cars, but under are current understanding of physics, isn't possible.

So if we say weight is mass, then you're right, adding weight to a car is generally a bad thing but as you correctly identified, sometimes you need to add mass to certain parts of the car to improve the weight distribution, this is to improve the balance of the car. If the the car is light at the back you would add ballast weight to the back of the car to help give the rear of the car a bit more grip. Usually though you would add a rear wing instead as that has the effect of adding weight (not real weight) to the rear of the car at speed without adding mass.

 

[C-ZETA]

Originally, I would have had HP, but now I think that lack of kg is more valuable.It's a bit like real life, Caterham for example produce superbly light cars with minimal power and they still have incredible speed.

 

[Paulie]

Just a quick note, because weight is worth so much PP in them, power is actually more valuable in the /Tuned versions of the Elises.

 

[BobElHat]

What this discussion seems to be missing is the design of the PP system. In theory, on some hypothetical average track, cars which have the same PP should have similar performance. So, for this hypothetical average track, the performance you lose from 1PP of extra weight should be the same as the performance you gain from 1PP of extra power. The same goes for all the other options which affect PP - the performance you gain from switching from R1s to R2s should be the same, at this average track, as the performance you would gain if you used that PP for more power, less weight, or more downforce.

At least, that's the idea. In reality we never drive this hypothetical track and the PP system is only a rough approximation to this ideal. It's still useful to think of this average track as a starting point though.

So, back to the question of which is better: Less weight or more power? It depends on the car and the circuit. If the circuit is twistier than average (eg. Eiger), cornering speed matters more than at the average circuit so favour lower weight over higher power. If it's faster than average (eg. Fuji), top speed matters more than at the average circuit so favour higher power over lower weight. If you car is heavier than average, favour reducing weight. If it's less powerful than average, favour increasing power.

The most important thing to remember is that data always beats theory. Theory can point you in the right direction, but you can only find the right answer - the fastest setup - by testing.