MisterCorn
Fuji
- Joined
- 8 Jan 2011
- Messages
- 9,411
I was only going to go for the one light. If you do multiple ones then it makes it more awkward to set up again as you need different values of each gears.
The thinking is exactly as you say. You are driving along, the light comes on, you need to register the light and react to it. The revs will continue to rise until you have come right off the accelerator, so it is the time from when the light comes on until you come of the accelerator. I haven't any good data from the C4 but I did look at this on my turbo not long ago. Admittedly the turbo is running a lot more power so the effect will be more pronounced, but it is also running longer gearing and weighs more. First gear.....
You might not be able to see on there, but this shows that it took 0.2s from starting to come off the accelerator until the engine reached peak RPM. During this time the revs rose from 6100 to 7050rpm. That was at 84% throttle.
Same for second gear.
In this case 0.4s from starting to lift off, from just over 90% throttle, until the engine revs peak. During that time the revs rose from 6500 to 7000 revs. In terms of the rates of rev rise I see the following:
First gear, 3300 – 6800rpm, 1 second
Second gear, 5300 – 6850rpm, 1 second
So if you assume 0.2s from starting to lift off until peak revs, and a 0.3s reaction time, from when the light comes on until you start to lift. To get a shift point of 6800rpm you would set the light at 5250rpm in first and around 6100 in 2nd. That way you can be as consistent as possible when the lights come on and get the desired shift point.
Depending on the power curve I will probably set the limit lower in first to give some headroom, as you can see on the turbo the revs rise at such a speed it is really easy to hit the limiter. If you are off by 0.2s you can have an extra 1000rpm
MC
The thinking is exactly as you say. You are driving along, the light comes on, you need to register the light and react to it. The revs will continue to rise until you have come right off the accelerator, so it is the time from when the light comes on until you come of the accelerator. I haven't any good data from the C4 but I did look at this on my turbo not long ago. Admittedly the turbo is running a lot more power so the effect will be more pronounced, but it is also running longer gearing and weighs more. First gear.....
You might not be able to see on there, but this shows that it took 0.2s from starting to come off the accelerator until the engine reached peak RPM. During this time the revs rose from 6100 to 7050rpm. That was at 84% throttle.
Same for second gear.
In this case 0.4s from starting to lift off, from just over 90% throttle, until the engine revs peak. During that time the revs rose from 6500 to 7000 revs. In terms of the rates of rev rise I see the following:
First gear, 3300 – 6800rpm, 1 second
Second gear, 5300 – 6850rpm, 1 second
So if you assume 0.2s from starting to lift off until peak revs, and a 0.3s reaction time, from when the light comes on until you start to lift. To get a shift point of 6800rpm you would set the light at 5250rpm in first and around 6100 in 2nd. That way you can be as consistent as possible when the lights come on and get the desired shift point.
Depending on the power curve I will probably set the limit lower in first to give some headroom, as you can see on the turbo the revs rise at such a speed it is really easy to hit the limiter. If you are off by 0.2s you can have an extra 1000rpm
MC
