...or you can just set gearing so you shift around peak hp and next
gear falls around peak torque.

Generally, i'd just set top gear to be around max hp at end of fastest
straight, then fine-tune gearing so you are between both peaks when
cornering. There isn't a perfect gearing for all tracks.

Quote from Neilser :

Nice graph, though the horizontal axis only seems to be RPM for the engine curve, and the others appear to use road speed.

I war really looking for that kind of graph 'cause I always change gears on rpm not speed

But you cannot plot that graph against engine RPM. You can plot it against wheel RPM, which is the same thing as road speed (ignoring slip).

There is a lot of crap in this thread!

Fonnybone - shifting at peak power and getting the gear spacing so you drop to peak torque in the next gear will make you an awful lot slower than you could be. Why lost time on the track for the sake of a bit of thought?

sorry,

Quote from tristancliffe :

Fonnybone - shifting at peak power and getting the gear spacing so you drop to peak torque in the next gear will make you an awful slower than you could be. Why lost time on the track for the sake of a bit of thought?

Oh my dear, dear Tristan I guess i just have more important things to
think about than to enlessly study graphs to get the world's most optimum
gearing. I said 'around' peaks. I probably spoke (wrote) a bit too fast there
though. Actually, i won't space the gearing that wide, but redlining to fall
back 1000 rpm is just daft. The time spend shifting often offsets the marginally
better acceleration, more so irl, in a proper manual. Using hp/torque peaks as
guidelines isn't gonna make you an awful slower, but it probably wouldn't
be optimal either. I've never felt much slower than others on track.

We've always agreed that setting gears for top speed and corners was more usefull
than getting perfect gear overlap... How about putting that energy on people
who are spreading much more uneducated information.

2010 is starting to look just like the ones before it...

Quote from tristancliffe :

But you cannot plot that graph against engine RPM. You can plot it against wheel RPM, which is the same thing as road speed (ignoring slip).

There is a lot of crap in this thread!

Em, not sure to whom the "crap" remark was directed but I'm aware that you can't plot that graph against RPM in that fashion and still be able to see the crossing points for the gears. However, it was plotted against RPM, making the horizontal axis just plain wrong for all but one of the traces plotted...

Edit: I should add two things... Firstly, I actually agree that a lot of crap ends up in threads like these, and part of this is because people don't read the first pages once the thread gets a few pages long Secondly, a few weeks ago in a thread amazingly like this one, AndroidXP wrote a beautiful summary of the whole "when to shift"/"shift light" situation... As far as I can see he got it all absolutely correct, and answered just about every issue people have raised. It would be cool if lots of people read it now before adding extra posts

On a side note, the time it takes to shift affects gearing choices. I recall that a world record run at Blackwood in the LX6 only used 3 gears (other than the initial start). With a much faster shift time, a Formula 1 race car will use all 6 or 7 gears or at least all but 1st gear, on a track like Spa.

So I understand that unless power drops significantly before redline I should change gears just at redline because torque at next gear will always be lower?

Quote from AndRand :

So I understand that unless power drops significantly before redline I should change gears just at redline because torque at next gear will always be lower?

Well, almost, but not really

Firstly you need to know how much the power drops beyond the peak...
Secondly it depends on how much the gears are separated. E.g. between first and second gear, it's very likely you'll need to redline it. Between 5th and 6th though, much less likely...

Quote from Neilser :

Between 5th and 6th though, much less likely...

What I saw at MotoGP and SBK as they almost skip 4th or 5th to get to topgear (prolly due to least loss on transmission that probably is direxct at top gear
ie. http://www.youtube.com/watch?v=wxlu-dvj6qM

So no easy explanation on when I have to shift ?
"When being near the number 7" or something simple and understandable like that?

ok you want it simplified. It can't be, every car is different. They all have the optimal shift point at different places in the rev range. Your best bet if u really want to see, is get LFS Z, and see the shift RPM the old shift light uses. otherwise it's just a matter of practice. Take the cars to the drag strip, you'll soon learn where the best shiftpoints are by how it effects your times.