Where Do You Set Your Rev Limiter?

[Lavalover]

Just to be clear the FR-S does have a fuel cut off that kills power at high rpms. Not sure if the adjustment to the indicator light affects the operation of this cut off, or is it just a warning signal.

[hmong337]

7100. By the time the light comes on and going to make the upshift, should be 7300rpm.

[Vracer111]

7k rpm for me...see the shift indicator light and hear the beep every day...

[Maowc]

7300

[J_kennington]

Originally Posted by Lavalover

Just to be clear the FR-S does have a fuel cut off that kills power at high rpms. Not sure if the adjustment to the indicator light affects the operation of this cut off, or is it just a warning signal.

its just a warning. it doesn't matter if you set it at 2000 rpms. at 7500 the car will cut fuel

[Roadcone]

good lord some of you people are slow to react... i have mine set at 7300..

[LavosTRD]

And people wonder why their transmissions grind....

[BRZ_Lawyer]

I set mine at 3500 because I simply like to hear the beep, gives me the impression I'm revving hi. Note: I'm a daily driver, not a racer/tuner and have an automatic

Sent from my Nexus 4 using Tapatalk

[paulca]

Originally Posted by Mikem53

Then raise it... You want the peak torque to fall on the next gear when you shift..

Power is what you should base shifts on. Highest area under the curve.

[chrisl]

Originally Posted by paulca

Power is what you should base shifts on. Highest area under the curve.

Yep, and you want to shift when you are past peak power. Specifically, you want to shift so that you're making the same power in the next gear as you are in the current one. For example, if you're in a car that makes 200hp at 7krpm, 185hp at 7400rpm, 185hp at 6200rpm, and you lose 1200rpm when you shift at 7400rpm, you'd want to let it rev all the way out to 7400rpm before shifting. If you shift at the peak power point at 7000rpm, you'll drop down to ~5900rpm or so, where you'll be making less than 185hp, while if you delay the shift, you'll be making >185hp all the way up to 7400, and when you shift, you'll continue making 185+hp in the next gear as well.

(That doesn't mean you always want to shift at redline, just that you always want to shift past peak power)

[paulca]

Indeed and a car gear box is correctly tuned when it hits peak power at it's top speed and cannot go faster, cause if it tries to the power starts to fall and it stops accelerating.

Obviously this depends on a load of factors, most notably air temp and pressure, hills, road surface, dry/damp etc.

[OICU812]

People look at the dash while getting their F&F on?

[DarkSunrise]

Originally Posted by chrisl

Yep, and you want to shift when you are past peak power. Specifically, you want to shift so that you're making the same power in the next gear as you are in the current one. For example, if you're in a car that makes 200hp at 7krpm, 185hp at 7400rpm, 185hp at 6200rpm, and you lose 1200rpm when you shift at 7400rpm, you'd want to let it rev all the way out to 7400rpm before shifting. If you shift at the peak power point at 7000rpm, you'll drop down to ~5900rpm or so, where you'll be making less than 185hp, while if you delay the shift, you'll be making >185hp all the way up to 7400, and when you shift, you'll continue making 185+hp in the next gear as well.

(That doesn't mean you always want to shift at redline, just that you always want to shift past peak power)

The way I had always calculated it is, you have to compare torque to the ground (i.e., multiplied through the gearing) in the two gears. So to determine the shift point for the 1-2 shift, you would compare torque to the ground in 1st gear at 7000 rpm vs. torque in 2nd gear at 4500 rpm. Then 7100 rpm vs. 4600 rpm. Etc.

When torque to the ground in 2nd gear exceeds the same in 1st, that is your optimal shift point. If 2nd never exceeds 1st, then you should shift at redline.

Because of the way gearing is setup in most cars, it ends up that the optimal shift point is at/near readline in the lower gears, but gets lower as you go up the gears.

[paulca]

Remember that torque does nothing unless it "operates over rotation".

Throwing units out of it for simplicity.

Power output = Torque * RPM.

So DarkSunrise your method needs to take account of the drop in RPM the torque is applied at. (As above if you just forget the units and multiply torque directly by RPM is easiest). If you actually want "Watts" or "Horsepower" there are a few more complexities.

Examples....

200Nm torque @ 3,000rpm == 100Nm torque @ 6,000rpm.
200Mn torque @ 6,000rpm > 220Nm torque @ 4,500rpm.

In terms of power output, which is the energy transferred to the car in the form of momentum. aka Speed.

EDIT: And... if your engine is delivering 200Nm torque at 6,000rpm, regardless of what gear you are in or what size of wheels you have the actual power output at the wheels is the same. In a lower gear, you will just have higher torque applied at a lower rpm, same energy.