[Wally]

I've been calculating the optimal shift points for the season 13 cars, based on these assumptions from what I've found after googling around:

I've redone the calcs down here: http://xgn.com.au/index.php?topic=1545.msg28486#msg28486

You want to stay in the car's maximal torque band, meaning you want the RPM to be around the point where you're generating the maximum torque, say 4500 RPM for example. Every time you shift up, the car's RPM drops according to the gear ratios that you're shifting between.
 
 If 2nd has a ratio of 2.36, and 3rd has a ratio of 1.685, then when you shift from 2nd to 3rd, the RPM will drop by a factor of 1.685/2.36 = 0.71. So if you want your RPM to drop to 4500 after you shift into 3rd, you need to shift from 2nd at 4500/0.71 = 6300 RPM. This means that when you shift into 3rd, your RPM will drop from 6300 to 4500 and you'll still be generating max torque.

So if you know the RPM at maximum torque, and the gear ratios, you can calculate the optimal shift point.

Based on this, I've calculated these shift RPM (rounded to the nearest 50) from data in the game. If an RPM figure is over a car's redline, well, then redline it!

Supra
1 = 7450
2 = 6550
3 = 5750
4 = 5400
5 = 5500

Skyline
1 = 7300
2 = 6300
3 = 5800
4 = 5900
5 = 5650

RX-7
1 = 8650
2 = 7250
3 = 6950
4 = 6550

Nissan 370z
1 = 5200
2 = 4600
3 = 4100
4 = 4050
5 = 4050

The 370z has a very flat torque curve. If you shift at these points, you can pretty much stay in the maximum torque band most of the time.

I'm in the process of working with the author of the Race Essentials HUD app to see if he can allow you to set custom shift points for the app's "shift lights" in different cars.

[Rolz]

Why only 4 gears for the RX7 Wally?

[Wally]

Why only 4 gears for the RX7 Wally?

Because it's only got 5 gears, so 4 shift points.

[Bacchulum]

This is something I always use to set the gears (when that's an option).
Basically shifting between max. horsepower and max. torque.

Hopefully RaceEssentials can do something as you can't really see the RPM figure when driving.

[Phil.8]

In iracing used to use an app called shift tone, which seems to be now changed into sound shift, an app like this would be useful

http://nspace.hu/soundshift/

[Wally]

It's complicaaaated...

You need to consider the transmission torque, which is engine torque x gear ratio. You shift when the transmission torque in the gear you're in drops below what it would be in the next gear, at lower RPM.
Or you can also look at the power curve. You shift when the power in the gear you're in would become lower than the corresponding power in the next gear. Which is all more complicated to calculate.

I can feel some programming coming on....

[Phil.8]

would be hard, in iracing they have all this available 

http://www.edracing.com/edr/Gear_Shifts.php

[marty]

I just shift by delta gain, see where it gains or loses and with ptracker pb delta at high setting its good for .001 increments so can tell fairly easily in straights. Quite often though I go as high as possible until I see a net loss on rpm. You also need to consider how many RPM you will lose during the shift so it will likely be a bit higher then your calc to allow for the loss by the time you get into the new gear.

[Wally]

would be hard, in iracing they have all this available 

http://www.edracing.com/edr/Gear_Shifts.php

There is just as much available in AC, "under the hood".

In practice, Marty, you only shift around about where you intend to anyway, plus or minus quite a bit of rpm every time, allowing for your reaction time and time to execute a gear shift.  So near enough will be good enough.

[Wally]

Take 2.

After more reading, I redid my calcs to take "transmission torque" into account, which is the torque delivered to the wheels according to the current gear ratio, instead of the engine torque (transmission torque = engine torque x gear ratio). So now I have found the RPM in each gear at which you will get more torque at the wheel by shifting up.

I've got most of an app in place where you just plug in the gear ratios, and it looks up the torque curve to calculate the optimal shifting RPM in each gear.

Supra
1 = 7680
2 = 6860
3 = 6350
4 = 6190
5 = 6230

Skyline
1 = 8000
2 = 8000
3 = 8000
4 = 8000
5 = 7940

RX-7
1 = 8500
2 = 8450
3 = 8350
4 = 8200

Nissan 370z
1 = 8000
2 = 7990
3 = 7800
4 = 7790
5 = 7780

Or to put it simply, in cars other than the Supra, you pretty much redline it in every gear. Only the Supra has significantly earlier shift points.

[Guybrush Threepwood]

This is great info Wally.  I always wondered about how you can judge the best RPM to shift.  Now I know that it's just a matter of asking you!

I never did "get" how to read the power/torque graphs though.

[Wally]

It's one of those weird things were there are lots of different opinions all over the internet.
Power vs torque? Peak power? Peak torque? Yada Yada Yada.
But this explanation makes sense to me.

[marty]

Even with that Info I dont think it would be something id look into unless I am clearly losing speed shifting, but as I said earlier you can easily see on your delta at upshifts if your gaining or losing. Using this data in practice Wally have you actually noticed any gain? Will we need to give you extra ballast to make up for the seconds gained knowing the optimum shift points.

[Wally]

Even with that Info I dont think it would be something id look into unless I am clearly losing speed shifting, but as I said earlier you can easily see on your delta at upshifts if your gaining or losing. Using this data in practice Wally have you actually noticed any gain? Will we need to give you extra ballast to make up for the seconds gained knowing the optimum shift points.

Ha, I've been too busy coding to really do any hot laps. It would mostly benefit the Supra. Anything else, just redline it. I might do some telemetry plots if I get a chance.

[marty]

You can compare with stracker fairly easily too but if you do a telemetry plot  then it would be interesting. But most important is if there is an actual time gain and how much gain doing this in a lap.

The r34 is no surprise max power is at the redline, you always needed to give it lots of rpm. What is the Supra's max rpm? I did get caught out switching from the Supra to 370 as just going my method I shifted earlier in the Supra. But in the 370 there was a significant loss shifting a bit too early  by significant loss Im talking .04 from hairpin to chicane or chicane to t1.

So shifting a bit short in that may cost .15 per lap or something so its noticeable but not a huge amount. You can lose .5 just by braking 2m too late into a corner and missing the apex. So focusing so much time on shifts isnt that important until youve got the other more critical parts down.

For uktimate laptime though every hundreth of a second counts, just no point focusing on areas of small gain for people that may be wasting much more with basic braking and hitting apexes.