dumrick wrote:There's other thing: with a limiter, do teams choose the last gear of a car to be slightly longer than needed to allow for higher speeds while overtaking in drafting or the speed differential is achieved merely by faster acceleration of the car behind, that reaches the limiter earlier?
I'm quite sure they set the gearing so that you only reach the rev limit on highest gear when you're drafting. Sometimes you can see the tacho on the screen during a race and it never hits 19k on highest gear in normal driving. I haven't seen the tacho during succesfull drafting, but I can only imagine it gets very close to 19k during it.
The point about faster acceleration is also valid and I'm sure it's partially that too. But it doesn't explain all of it.
West wrote:I'm sure there's a way to break the limiter... people tend to "get around" traction control; I don't see how breaking the limiter is impossible.
Of course there is. I have no idea which ways would pass FIA inspections, but there are many ways to get past it.
I've done some tuning on (streetable) Toyotas, which have a reputation of non-modable ecus. And often a standalone ecu is out of the question, when you're on a budget. One of the biggest issue is the stock limiter, which many say is impossible to overtake without changing the ecu. But there are at least two ways.
Say you have a limiter at 6k rpm. That's 100 revs/second, or a rev every 1/100 second. Say you're getting a rev pulse every 1/100 of a second. Any faster and the ecu cuts the fun. Lets also say the ECU has a 10MHz crystal. It means 100 000 ticks for 1/100 seconds.
I'm sure many already figured out where I'm going.
1) Change the oscillator to faster one. ECU has no idea of real time, it's only counting the crystal ticks. Say you go from 10MHz to 12Mhz, an increase of 20%. In real life you're still getting rev pulses every 1/100 s, but the ECU sees it's taking 120k ticks between rev pulses and believes you're at 10M/120k*60=5000rpm . You can now up the real life revs by 20% into 7200rpm, which is 120 revs/second or 1/120 second, but with the faster 12M crystal, the ECU is now counting 100k ticks between rev pulses and thinks the rev limit is there. The ECU sees the 20% up as going from 5000rpm into 6000rpm.
2) Limit the rev output to ECU into rev limit. You need a box between the ecu wiring. If the rev limit is 6k rpm, the box just passes any rev info below that straight to the ecu, but anything over that and it just lets the ecu see the 6k rpm.
(needless to say, but in both cases you have to consider what happens to ecu outputs, like injector open times and ignition)
I'm sure the engineers have to get more creative in F1 and FIA blocks basic things like these though.
