Nabu

Gears must have been one of the best mods on the car.

Even on a track ,like Spa or Nurburgring, with long straights there isn't any reason why not having them. Not on a NA machine at least. If it had more power then yes.

Keep in mind the car was running a lot slower than normal. The gear change would be a lot more rapid if it was running properly

MB

My only worry about 4.7 is hitting the limiter on corner exits too early, and having to make extra shifts on the straights (loses some time)k
How do they perform on some tighter circuits? I guess better there.

I might get a 4.7 diff built up as a swap out unit.

Nabu

There can't be a perfect ratio for all tracks out there. That's for sure.

Indeed, gear changes are increased and gear change time makes a huuuge difference in total laptime.

There is another member with whom we visit the same tracks. He installed 4.44 and his overall laptime has indreased a bit due to the addition of one more extra gear shift. But his gear change pace is a lot slower than mine. And takes a lot of improvement.

We have sat and looked at the data and indeed he loses speed at the back straight when making that extra shift.

But, my argument is that with the 4.77 the engine puts more torque on less rpms. This makes up imho, plus i don't feel like i have to be at 8.000rpm all the time to get some power.

Can't comment on the tracks you are racing at as i don't have any experience at all but the only gear which loads fast enough to cause handling issues (at the corner exit) is 2nd. How many corners are at that speed? Thats somewhere to start.

lovegroova

Some useful discussion on Final Drives here: https://www.s2ki.com/s2000/topic/102...-final-drives/ and here: https://www.s2ki.com/s2000/topic/100...#entry22393092

I think you probably have to do some proper data analysis of various corners to see what's best.

An example would be the La Source Hairpin. If I look at my video I can see the following ( I have standard 4.10):

• My minimum speed there is about 32mph/50kph. The ideal gear for that is 1st.
• At corner entry, I'd need to either shift down whilst turning and braking, which is pretty tricky to manage and could quite easily result in locked rear wheels/effective lift off oversteer.
• At corner exit I need to change into 2nd at around 42mph/67kph and at that point, I still have quite a lot of lock on and again, the effect would be similar to lift off and significantly increase the chances of a spin.
• Also to factor into that is the time lost whilst shifting.

So, in summary for a 4.10 car, 2nd is better here than 1st.

4.77 would probably be better again, as the max possible speed in first is 37mph/60kph. So it is closer to the minimum speed.
You would still have sufficient max speed in 2nd to be able to drive through the corner without needing to change down to first, and you get the benefit of higher rpms (and thus more power).
However, you need to take into account that the extra speed gained from the better acceleration from the apex would cause a loss of traction (i.e. can the car still go through the exit given the extra speed). so, whther you can use your extra acceleration needs to be factored in as well


Let's take a look at Pouhon, a high speed corner.

• My minimum speed there is about 75mph/120kph. The ideal gear for that is 3rd.
• In a 4.77 car, you would have to use 4th as your max speed is 78mph/125kph
• Therefore the 4.10 geared car would give a faster exit as you'd get better acceleration from 75-90 in 3rd than you would in 4th in the 4.77 car.
• But you would still be changing up at corner exit with a lot of cornering force on the car, so some skill would be required. You'll note that I do the whole corner in 4th as it's much easier/safer that way!

Hope that helps, I'll take a look at the video later

lovegroova

Wow, 2:57 is seriously quick! I'm not sure I dare criticise that, though I would perhaps say you tend to turn in a bit early, though that may simply be down to the much higher speeds you are doing!

Awesome lap!

s2k_Nut

You really attack the circuit Nabu super driving

Nabu

Very nice analysis here. Many factors to be considered though. From my understanding your S2K is pretty much stock, so everything above stands for an almost stock S2K as well. If i try comparing this to the data i have i find many many things to be different.
The speed that each car can carry at a turn, v-tec points, aero etc (which helps a lot at corner exits) etc.

One small example. At La Source hairpin my minimum speed is 36mph/58kph. That there is almost the limit of 1st on a 4.77 (as you mention above).
Considering this in conjuction with my lower V-tec point - 5.200rpm + lower weight and 2nd is considered almost ideal.

Thing again is that gears totaly depend on how they work with each car's specific build. For example at Pouhon my min speed is 78mph/126kph and i found 5th to suit me more than 4th which was in very high revs (if not over the limiter), asking for very precise foot and steering wheel work.
As you can see in the video, no extra shift at the exit = no time lose at all.
In a standard s2000 though, the assumption above could very well stand true.

Anyhow, its always very interesting analysing different approaches and having this kind of chat

Nabu

If its any help, here is the actual diagram of the lap.

lovegroova

Yes, my car is pretty much stock, bar the Bilsteins which don't make a massive difference t lap times.

I agree absolutely. Shorter gearing would be a big help with the minimum speed of 36/58, as you are nearer to the power that way.
However, if the minimum speed were 58mph/95kph, then 4.10 gears would be better than 4.77, as you'd have to be in 3rd in the 4.77 which would be slower than 2nd in the 4.10.


As I mentioned in passing, I do the same/similar as you for Pouhon, using 4th instead of the more "ideal" 3rd - it's much easier that way, I'm sure you understand that upshifting halfway out of the exit would be pretty scary stuff


It's certainly good to be able to chat about this as it's very interesting.

It'd be interesting to do some "straight line" testing using data logging to see how much advantage you would get from using different gears from various speeds.

For example, you could do a run from 30kph starting in each of 2nd and 3rd gear up to 150kph and then you could figure out which gear would theoretically be best for various minimum corner speeds. (You would do a few runs of each type to make sure you have some consistency with gear changing

That would be a great starting point and then you'd need to factor in things like "the Pouhon effect" where using a "non-ideal" gear is better.

lovegroova

Oh, that's very interesting, I'd love to have the data so I could compare your lap with mine!

I just did some simple maths and average speeds are:
Nabu: 88.7mph/142.7kph
LG: 82.0mph/131.9kph


Nabu finishes the lap 528m ahead of LG (who is about to turn into the bus stop as Nabu crosses the line).