HP loss from FM1 to FM6?

[jrbabbitt]

I do have a curious and valid question that I have searched before posting...
Has anyone found out the average HP loss when you change FM settings from FM1 to FM6?
This is one parameter that does not have an answer in the numbers nor the PP numbers. Example; I'm running the WTC700 at Le Mans and my McLaren is at 699.34 PP and considering I'm at full power ( 520HP)with relation to the required PP numbers at FM1 and when I drop it down to FM6 I'm at less power but I have no idea how much HP I'm at.

Is there a valid answer for this?

 

[Famine]

Is there a valid answer for this?

Yes. But also no.

There's no actual place anywhere in the UI that gives this information. However it wouldn't be terribly difficult to calculate. You'd just need Special Stage Route X, fuel consumption turned on, and the figures for the top speeds you achieve at each FM level as you click it down going down the back straight.

Top speed for a given vehicle - or rather the change in top speed for a given vehicle in a single configuration - depends on almost exactly one thing: engine power. If you reduce your engine power by X, you reduce your top speed by the cube of X.

For example, if your 520hp car can do 180mph in FM1 and you click it down to FM2 and it can now do only 176mph, that's a reduction in speed of about 2.3%. Your engine power would thus reduce by the cube of 2.3%, or about 7% - making it now 486hp.

It's a little trickier with cars that have big aerodynamic aids as weight is generally ignored because it has a small effect that isn't variable. Aerodynamic aids however are variable in terms of what downforce (weight) they generate at given speeds, so that adds a layer of complexity as I have no idea how the aero calculations work in GT.


Edit (and edit): Just ran a quick test in a 631hp Murcielago LP640. In clean air, I got

FM1 - 221mph
FM2 - 219mph
FM3 - 214mph
FM4 - 212mph
FM5 - 208mph
FM6 - 198mph

Although I think the speed for FM3 was influenced by the tunnel (it did not like the tunnel at FM5; speed dropped to 206mph before rising again), that would roughly correspond to:

FM2 = -1% speed = -2.8% power = 614hp
FM3 = -3.3% speed = -10.1% power = 573hp
FM4 = -4.2% speed = -13.3% power = 557hp
FM5 = -6.3% speed = -19.9% power = 526hp
FM6 = -11.6% speed = -39.1% power = 453hp

So I'd estimate that the figures are supposed to be -3% or -5%, -10%, -15%, -20% and -40%, or thereabouts.

 

[jrbabbitt]

Deleted... sorry

 

[zeltus]

Yes. But also no.

There's no actual place anywhere in the UI that gives this information. However it wouldn't be terribly difficult to calculate. You'd just need Special Stage Route X, fuel consumption turned on, and the figures for the top speeds you achieve at each FM level as you click it down going down the back straight.

Top speed for a given vehicle - or rather the change in top speed for a given vehicle in a single configuration - depends on almost exactly one thing: engine power. If you reduce your engine power by X, you reduce your top speed by the cube of X.

For example, if your 520hp car can do 180mph in FM1 and you click it down to FM2 and it can now do only 176mph, that's a reduction in speed of about 2.3%. Your engine power would thus reduce by the cube root of 2.3%, or about 0.7% - making it now 516hp.

It's a little trickier with cars that have big aerodynamic aids as weight is generally ignored because it has a small effect that isn't variable. Aerodynamic aids however are variable in terms of what downforce (weight) they generate at given speeds, so that adds a layer of complexity as I have no idea how the aero calculations work in GT.


Edit: Just ran a quick test in a 631hp Murcielago LP640. In clean air, I got

FM1 - 221mph
FM2 - 219mph
FM3 - 214mph
FM4 - 212mph
FM5 - 208mph
FM6 - 198mph

Although I think the speed for FM3 was influenced by the tunnel (it did not like the tunnel at FM5; speed dropped to 206mph before rising again), that would roughly correspond to:

FM2 = -1% speed = -0.3% power = 629hp
FM3 = -3.3% speed = -1.1% power = 624hp
FM4 = -4.2% speed = -1.4% power = 622hp
FM5 = -6.3% speed = -2% power = 618hp
FM6 = -11.6% speed = -3.7% power = 608hp

So I'd estimate that the figures are supposed to be -0.5%, -1%, -1.5%, -2% and -4%, or thereabouts.

Good analysis except you have your exponential reversed.

 

[Greycap]

Good analysis except you have your exponential reversed.

Correct. To increase speed from 198 mph to 221 mph is an 11,6% increase (it would be a 10,4% decrease if starting from the larger figure, another problem in the calculations) which requires an almost exact 39% power increase. To reverse that, the originally 629 bhp engine is down to ~453 bhp at FM6, or about 72% power.

Back in GT Sport someone - can't remember who - calculated the power levels being 100-96-92-88-84-80%, no idea if it was true and if it applied to all engines or just one they tested it with. In any case they were pretty believable figures.

 

[Famine]

Good analysis except you have your exponential reversed.

Oh yeah. I blame Rockstar Games.

 

[zztmktn]

Here are values derived from some tests I've done.

Fuel map	Engine power output (%)	Fuel consumption (%)
1	100	100
2	96.0	90.0
3	92.0	80.0
4	88.0	71.0
5	84.0	63.3
6	80.0	54.6

I'm pretty confident about the fuel consumption, but there may be some errors (±0.5) for the engine power.
Note that the tests were carried out on GT7 v1.52, and the test car was the Bugatti Chiron. It is possible that the fuel map behavior has been changed by updates, or it is entirely different for other types of cars.

Edit: I just did a more precise test with the Audi R8 GT3 Evo and updated the table. Each step seems to be a simple 4% output reduction.

 

[Greycap]

Although I think the speed for FM3 was influenced by the tunnel (it did not like the tunnel at FM5; speed dropped to 206mph before rising again), that would roughly correspond to:

FM2 = -1% speed = -2.8% power = 614hp
FM3 = -3.3% speed = -10.1% power = 573hp
FM4 = -4.2% speed = -13.3% power = 557hp
FM5 = -6.3% speed = -19.9% power = 526hp
FM6 = -11.6% speed = -39.1% power = 453hp

So I'd estimate that the figures are supposed to be -3% or -5%, -10%, -15%, -20% and -40%, or thereabouts.

Those percentages are still the wrong way round as you've used the FM6 power as a starting point and those are the increases from it, not decreases from FM1. Basic maths, the same absolute difference is a different percentage depending on what it's compared to. The extreme example: the starting point is 100, add 50% to it, you get 150. Now get back to 100 and it's certainly not -50% but -33,3%.

The actual power loss percentages, when being compared to full power, would be:

FM2: -2,4%
FM3: -8,9%
FM4: -11,4%
FM5: -16,4%
FM6: -28,0%

Which puts them a whole lot closer to what @zztmktn has above.

 

[Famine]

Those percentages are still the wrong way round

FM6 = -11.6% speed = -39.1% power = 453hp

the originally 629 bhp engine is down to ~453 bhp at FM6

I guess we're both wrong then.

631hp on the unrestricted engine, by the way.

 

[Greycap]

I guess we're both wrong then.

Nope, only you. Percentages don't work both ways with the same results. When you add 39,1% to 453 bhp it's indeed ~630 bhp, but remove 39,1% from 630 bhp and you'll end up with ~384 bhp. It's not debatable, it's mathematics.

 

[Famine]

Nope, only you. Percentages don't work both ways with the same results. When you add 39,1% to 453 bhp it's indeed ~630 bhp, but remove 39,1% from 630 bhp and you'll end up with ~384 bhp. It's not debatable, it's mathematics.

I think you're confusing me with someone who doesn't know the difference between in and by when it comes to percentage changes, or the concept of dividing by a value being the same as multiplying by the inverse. Weird we ended up at the same value, but you think I didn't maths it right.

631hp still, by the way. I've only posted it three times. Perhaps when you're pontificating - and adding nothing to the thread - about "basic mathematics", start with getting the actual numbers right.

Your next message in this thread is helpful and a contribution to the original question.


In the meantime, I ran another test with a more powerful, faster, and not quite as overtly (and adaptively) winged car as the Veyron. This is the Genesis VGT:

FM1 - 259mph
FM2 - 256mph
FM3 - 252mph
FM4 - 249mph
FM5 - 244mph
FM6 - 237mph

It's listed at 869hp, although now I say that I'm reminded it's a hybrid and GT7 isn't great at displaying the electric part of a hybrid's power output.

 

[jrbabbitt]

Here are values derived from some tests I've done.

Fuel map	Engine power output (%)	Fuel consumption (%)
1	100	100
2	96.0	90.0
3	92.0	80.0
4	88.0	71.0
5	84.0	63.3
6	80.0	54.6

I'm pretty confident about the fuel consumption, but there may be some errors (±0.5) for the engine power.
Note that the tests were carried out on GT7 v1.52, and the test car was the Bugatti Chiron. It is possible that the fuel map behavior has been changed by updates, or it is entirely different for other types of cars.

Edit: I just did a more precise test with the Audi R8 GT3 Evo and updated the table. Each step seems to be a simple 4% output reduction.

THANK YOU, you made my day.