BHP changes once you buy a car!

Stephanos82

Stephanos82

216
Hi, I don't know if anyone has already posted a thread about this yet (I couldn't find one) but I was wondering why the bhp reading in dealership changes once some cars are bought! (It's been happening since the first Gran Turismo, I think).

I have read about the "gentlemen's agreement" that concerns Japanese sports cars stick to or under 276 bhp but the changes do not only apply to Japanese Models!
Some examples of cars that their bhp rating changes (either increases or decreases) after purchase:
Ferrari 430 Dealership: 483BHP , Garage: 495BHP
Lotus Elise 11 134BHP, Garage 133BHP
Bmw CSL 355BHP, garage 354BHP
S2000 06 238BHP garage 235BHP
Mazda Rx8 Type S 246BHP garage 248BHP
And many many more

I've always imagined that there's a mysterious linked to reality reason PD does that! Maybe, the dealership bhp is the one advertised but the garage one is the one PD came up when they actually dynoed the car themselves. Another one of my assumptions is that dealership is the one claimed and the garage is the one given to PD by the manufacturer along with a bunch of other data that would help replicate the car in game!

What do you think?
 
The GT5 (and probably earlier versions) had this 'feature' implemented for all cars that you buy. So you bought a car, and it has less hp, then you do break-in and power increases over time.

However, this is not the case for GT6 generally. But as you write, some models have difference. So this is imho exception (another inconsistency, bug, flaw ?). Usually, if you buy GT6 car in dealership, it will have the same HP (which is not the case in GT5)
 
You should buy every car in the game and document the changes between dealership and garage power specs.

Some cars get a massive increase in power, while others get a massive decrease.

It's highly illogical and unrealistic in most cases. Very annoying. Wish it didn't happen.
 
Tornado
It's not a bug. PD deliberately has it set up that way, and they have since GT1.




As to whether their reasoning for it is sensible...
Click to expand...

I too believe that there has to be a sensible reason as to why they are doing this, I just don't know what it is! I was hoping that I'd find someone who had got to the bottom of this or at least shed some light to the matter! :)

SuzukaStar
You should buy every car in the game and document the changes between dealership and garage power specs.

Some cars get a massive increase in power, while others get a massive decrease.

It's highly illogical and unrealistic in most cases. Very annoying. Wish it didn't happen.
Click to expand...

As I said above, I'm hoping that the reason is both logical and realistic. Personally, I don't find it at all annoying but I still want to know why!
Buying all the cars and documenting changes is not my cup of tea :( I would not dare take such a huge task upon me. The fact that it happens is enough.
 
Not all cars have different garage HP. The 2002 Nissan Skyline GTR NUR gets a great power change, but there is no change in the 1970 Honda Z ACT
 
SuzukaStar
Bought the Lexus IS F '07 today.

Car info screen mentions 416 hp, dealership says 417 hp.

Garage says 445 hp :dunce:
Click to expand...

That is indeed confusing.. The official specs say 416bhp. Is it possible PD dynoed an IS F that was slightly tuned and imported that car's output into the game?
Moreover, it is possible they confused the IS F engine with the LS 600h one? The latter makes 445bhp !
 
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Yes, acceleration rate is more or less the same between GT6 tracks.

I checked TestTrack vs Monza vs Fuji. (Lemans is very bumpy, unrealisticly bumpy, so it's not good for comparison).

Re quote:

Mercedes SLS AMG
0-280 km/h: 23.8 sec Fuji
0-280 km/h: 23.1 sec SSRX
0-280 km/h: 24.5 sec Monza


Lexus LFA
0-280 km/h: 22.8 sec Fuji
0-280 km/h: 22.1 sec SSRX
0-280 km/h: 23.7 sec Monza

At Monza, I had to start in a corner and make some steering corrections (I am testing with DS3). This could be affected by a second or so.


Against real life and other tracks too:

Mercedes SLS AMG
0-300 km/h: 30.2 sec Monza (slight steering corrections)
0-300 km/h: 28.0 sec SSRX
0-300 km/h: 42.2 sec Real Life


Lexus LFA
0-300 km/h: 28.6 sec Monza (slight steering corrections)
0-300 km/h: 26.3 sec SSRX
0-300 km/h: 50.6 sec Real Life
 
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Furinkazen
engines appear to be a "what if they were unrestricted" scenario.
Click to expand...
That's probably what they were aiming for. It's strange however that they didn't make it a tuning option.

The implementation is quite OTT in many cases though (see Peugeot 905 pushing out more power than contemporary F1 cars).

As for the road cars I'm inclined to think it's just sloppiness. Probably separate people listing the power in the different sections with no communication or oversight (the story of GT).
YZF
acceleration/top speed
Click to expand...
They probably used crank-power rather than wheel-power in their equations.
 
Vegard
They probably used crank-power rather than wheel-power in their equations.
Click to expand...

The difference between crank/wheel power is about 20-50 HP, most of the time.

To make a 350 kph (220mph) car go 400 kph (250mph), you need 200-300HP extra.... so I'm still thinking this is the mistake in calculating aerodynamic resistance, somewhere in their calculations.

Adn that aero "advantage" is somewhere in the range of couple hundreds HPs

Because 0-200km/h(125mph) times are +- the same as in GT5 / Real Life. So IMHO it's not engine power...
 
YZF
The difference between crank/wheel power is about 20-50 HP, most of the time.

To make a 350 kph (220mph) car go 400 kph (250mph), you need 200-300HP extra
Click to expand...
Uhhh... it's a little less definitive than that. On both fronts.

The difference between crank and wheel power is about 15-30%, depending on drivetrain configuration and types of components used. This could be as little as 10hp in a Kei car or as much as 120hp in a supercar (or even more in something like the Tank Car).

To make a car aero limited to 220mph go to 250mph (assuming it has the gearing to do so), you need 47% more power. If it's super slippy and can reach 220mph with as little as 250hp you'll only need another 117hp, but if it's barn-door ugly and already needs 1000hp to go that fast you'll have to add another 467hp.

If you're talking about a BMW M5 with 500hp at the crank, it'll lose about 100hp through the drivetrain to put 400hp onto the road. If this makes it capable of 220mph, it'd need about 733hp at the crank (233hp more) to do 250mph.


The interesting part of your image though isn't the speed the cars are doing, but the engine revolutions required to do those speeds - apart from the Ford GT they all seem to be largely turning the same engine speed for wildly different road speeds. You can calculate which (if either) is right and which is wrong - and I largely agree with your aero-based assessment.
 
Furinkazen
LMP regs I have previously documented at great length, engines appear to be a "what if they were unrestricted" scenario.
Click to expand...
Well, for turbocharged cars that's a possibility. I still believe that PD just made up numbers to try to balance several decades of race cars with each other so they can be used as competitors. If it really was an earnest attempt to show PD's belief of "true" power numbers, it was spectacularly poorly done.
 
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Furinkazen
LMP regs I have previously documented at great length, engines appear to be a "what if they were unrestricted" scenario.
Click to expand...

I've never really bought that because the newer prototypes don't follow the same rule, nor do the other race cars. Those cars never race unrestricted anyway, so why even put it in the game with no option to turn it off. You can use the power limiter, but that is flawed in its implementation so the cars aren't the same as the real ones with the power turned down. I've always felt like it was to fudge the laptimes closer to what they should be, because the cars have never had enough cornering performance. GT6 has brought that a lot closer for some of the P1 cars, the TS030 which has the correct power output can run pretty realistic laptimes on RM or RS tyres. It also makes racing the AI even worse as they have cars that are massively quick in a straight line compared to what they should be - it breaks the balance too because the R10, R18, 908 and the TS030 all end up being really slow compared to the other cars because they don't have stupidly high power outputs.

Easiest fix is to add an option in the car setup that enables or disables restrictors and by default they're on. That way if you want to make a 1000BHP P1 car you can, but for those of us who don't want that we get the proper power outputs and the cars are as quick as they should be.
 
Famine
Uhhh... it's a little less definitive than that. On both fronts.

The difference between crank and wheel power is about 15-30%, depending on drivetrain configuration and types of components used. This could be as little as 10hp in a Kei car or as much as 120hp in a supercar (or even more in something like the Tank Car).
Click to expand...

Yes, that's why I mentioned a range: 20 - 50 HP. Not exact number. This range is what you have most of the time, meaning you measure 100-500 HP cars or something like that. I don't think that you can apply percentage here, because difference comes from drivetrain friction and other things, which are more or less constant. I.e. drivetrain loss in a M5, which produces 500 HP whould be that same as in the same M5, with a 400 HP mode enabled. There is a difference in the engine friction itself, but it's less proportionaly.
That's my thinking. I may be wrong, though.
Famine
To make a car aero limited to 220mph go to 250mph (assuming it has the gearing to do so), you need 47% more power. If it's super slippy and can reach 220mph with as little as 250hp you'll only need another 117hp, but if it's barn-door ugly and already needs 1000hp to go that fast you'll have to add another 467hp.

If you're talking about a BMW M5 with 500hp at the crank, it'll lose about 100hp through the drivetrain to put 400hp onto the road. If this makes it capable of 220mph, it'd need about 733hp at the crank (233hp more) to do 250mph.
Click to expand...

You are right. This is in real life. My 'power estimations' were based on GT5 (i took same car in GT5, added ~250 HP extra, and got the same speed as stock car in GT6). But this shows that even in GT5, aero is not perfectly calculated. As in real life you need much more.

So it seems that PD tried to improve aero but made it massively worse.
Famine
The interesting part of your image though isn't the speed the cars are doing, but the engine revolutions required to do those speeds - apart from the Ford GT they all seem to be largely turning the same engine speed for wildly different road speeds. You can calculate which (if either) is right and which is wrong - and I largely agree with your aero-based assessment.
Click to expand...

Actually there is nothing mysterious or interesting in revs at all... The GT6 cars accelerate so brutally fast above 300 kph, compared to GT5, that they run out of gears pretty fast and start bouncing of rev limiter. So most of the time I had to adjust gear box to match this "extra power" (or extra speed boost) to get the true difference. Ford GT, for example, has long enough stock gear ratios, so it isn't necessary for this car.

There are some other cars which have long enough stock gear ratios too. For example MB SL 55 AMG (GT5 - 330 kph, GT6 - 360 kph).
 
YZF
Yes, that's why I mentioned a range: 20 - 50 HP. Not exact number. This range is what you have most of the time, meaning you measure 100-500 HP cars or something like that. I don't think that you can apply percentage here, because difference comes from drivetrain friction and other things, which are more or less constant. I.e. drivetrain loss in a M5, which produces 500 HP whould be that same as in the same M5, with a 400 HP mode enabled. There is a difference in the engine friction itself, but it's less proportionaly.
That's my thinking. I may be wrong, though.
Click to expand...
You are - in fact powertrain losses can be different in each gear in the same car. The ballpark figures are around 15% for really efficient cars with the engine on top of the driven wheels (FF, RR and, to an extent, MR), more for those where they're at opposite ends and even more for cars that do both (4WD), with losses increasing as components sacrifice efficiency for durability.
YZF
Actually there is nothing mysterious or interesting in revs at all... The GT6 cars accelerate so brutally fast above 300 kph, compared to GT5, that they run out of gears pretty fast and start bouncing of rev limiter. So most of the time I had to adjust gear box to match this "extra power" (or extra speed boost) to get the true difference.
Click to expand...
You tuned them? You can't really be comparing like-for-like at that point, even if all you've done is lengthen the gears.

A stock E60 M5 will, without the limiter, hit a rev limited 211mph in 7th, but the CdA and approximate wheel power rating suggest it'll max out at 198mph. Handily that occurs at 7,750rpm in 7th, which is also exactly where the peak power is - as if BMW knew what they were doing :lol:

If the car in either game will cruise past that on the flat at SSRX, it either has too much power or too little drag and I largely agree with you that it's the drag that's lacking.
 

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