EDIT: Table of Contents

Simulations In Order of Appearance
1) ap1 FD gearing
2) ap1 vs ap1 w/4.77 vs ap1 SC'ed
3) ap1 vs ap2 vs ap1 w/MY04 tranny
4) ap2 FD gearing
5) 400+ whp turbo ap1


since i joined s2ki, i felt like i've learned a lot about the S and cars in general. a hot topic i've seen on s2ki is FD gears, and how they affect acceleration, top speed, 0-60, quarter mile time, etc.

i've written a code using matlab that simulates WOT acceleration runs. for my first comparison, i used FD gears as my variable; here i compare 4.10, 4.44, 4.56, and 4.77 FD gears. The nice thing about running a simulation is that all the "cars" have the same engines with the same output, same weight, same areodynamics, same wheel sizes, same launches, same shift points and shift speed. IOW, the only variable becomes the FD gears. finally, i'm not saying which gear is better or worse, i'm just quantitively comparing the "same condition" acceleration characteristics of these gears, and also, these simulations should not substitute advice from others with gears or trying these gears yourself. in the end, it's the driving experience that satisfy us

some background info with the sims:
ap1 engine & tranny
weight of driver is around 150 lbs
OEM wheels & tires
shifting at 9k
shifts made in .35s (experts please comment on whether this is a decent estimation)
** launches are hard to simulate, and i tried to incorporate it into my dyno as it only matters in 1st gear (it behaves as tire spin then locking at around 4k rpm)

ok, starting with the dyno


this is the effective wheel torque through all the gears. you can see that the 4.77 offers the most mechanical advantage while having the lowest top speed


0-60 run. the 4.77 gear loses because it requires an extra shift


top speed. notice stock and 4.44 gears are still drag limited, while the 4.56 and 4.77 gears are gear limited. also FYI, if you're stock and you want to try to max out, it takes around 80 seconds


quarter mile run. 4.77 wins, and from what i see from a zoomed in graph, the 4.77 pulls ahead and never falls behind.


** no flames please , you should take it with a grain of salt as in a real race, gears will NOT be the only variable.

** mods, i don't know if this is too technical for s2000 talk, so feel free to move it.

 

This thread delivers

 

4.77 FTW!!!

 

Great job

 

wow you wrote a program? great job. much respect.

 

very nice! i can't enlarge the pictures though. this information would really help those that are stuck deciding upon which FD they really want to go with. i am leaning towards the 4.56 or 4.44's

 

Wow this is really cool, it seems like the stock isn't very efficient...
to the OP: would you mind sending me the code, I really want to take a look at it and see how these FDs affect ap2s.

 

choungsgay, with a harder launch (more torque on the pavement at start) the sim would yield better quarter mile time. also, i could easily modify the code to see how an ap2 would run. all i need to do is use a different array for torque at all rpms, different wheel size, different tranny numbers...but i dare not start an ap1 vs ap2 battle

pm me your email and i can send it to you in txt format. the syntax in matlab is pretty self explanatory.

 

Now how about getting a dyno plot for a Comptech or Vortech equipped car and plugging in those numbers.

Nice work!

 

We did the exact same project in my automotive engineering class, we were testing the top speed of a 100cc motorcycle. I would love to see you code and the parameters you used for the s2000. PM sent