cujet

Conclusion: God, it's much more pleasant to drive and faster in real world conditions.

My 2004 W/Inline Pro Stage 1 turbo kit was really a pain to drive with the stock 4.10 differential. At 19.5 pounds of boost, 1st, 2nd and sometimes 3rd gear were traction limited. Also, there was not enough time in each gear when there was traction. Shifting like crazy was not fun here in straight and flat South Florida. In addition, the added power/torque really could utilize "taller" gears.

So, I contacted PuddyDad for a set of 3.63's. He had a new set in stock and I purchased them.

I finally got around to installing the gears and I wanted to report on how the car feels, how the acceleration was affected and the current RPM's at various speeds. I did go one size up on the tires too (255/40/17 rear)

First, the gear spacing "feel" is not appreciably affected. In other words, it's still a close ratio transmission and the RPM drop between shifts seems to feel similar to before. However, there is increased speed in each gear. The gears match the power perfectly.

Second, the real world rate of acceleration in the first 3 gears is actually MUCH better, due to significantly less wheelspin. I actually get good traction in 2nd gear now!! Coupled with the fact that the turbo can stabilize longer in the lower gears. There is also one less shift in the 1/4 mile (I don't launch hard) . My G-Tech is showing about 10% lower "G's" of acceleration in each gear, but each gear is held longer. This means that the earlier upshift that would have "killed" acceleration by 30% is postponed. The result is quite positive. This is a proper gearset for a 400HP 2.2L engine. I don't want to break my new gearset, so I'm not going to run a true 1/4 mile for you guys. I strongly suspect the results would be very much the same as before.

Third, the RPM on the highway now feels "correct". Don't worry, with the turbo setup, there is plenty of torque in 6th at highway speeds. (70MPH limit here, most people go 80) Since my setup builds significant boost (Verified, boost climbs to 10PSI 70MPH) at 3300, there is boost in 6th at 70MPH.

Also, top speed should be around 170MPH if there is enough power to overcome drag. Note: there is no way I'd ever try that, regardless of location.


6th gear GPS Speeds, indicated RPM:

55MPH, 2600 RPM
63MPH, 3000 RPM
70MPH, 3300 RPM
80MPH, 3800 RPM
85MPH, 4000 RPM


Disclaimer: I posted this in "forced induction" due to the fact that such a gear change would be inappropriate for a normally aspirated, stock displacement S2000.

Special Thanks to Ben "PuddyDad" for helping me properly set up the differential. Everything he did for me was absolutely perfect. He get's my highest recommendation!!

riceball777

I really need to do this for my car. The stock 4.1 rear gear is killing me. I have no traction in the first 3 gears. Plus I have a striker 2.4l so my redline is only 8,000 rpm.

sohc_mshue

I run a 3.9 in my car and it is great at 650+whp on my mt et streets. Plenty of traction and acceleration.

benes2k

love the results of this. was wondering if such a low ratio would affect your overall speed but im impressed.

I would like to see a comparative benchmark though.

liquid_helix136

I'd imagine that the gear set would help tremendously, especially in a drag racing scenario. You *should* have longer gears with the more power you have.

riceball777

I would think with a final drive this low it would mess up the speedo really bad. If your speedometer says 80mph your probably going closer to 90mph. How can you fix the speedo error?

The modifry yellow box only fixed the speedo that reads to fast from going with a bigger final dive like a 4.4 or 4.7. It won't fix a speedo that reads to slow from lowering the final drive like in this case.

liquid_helix136

Ricks makes one that does up to -50% / +100%

http://www.ricks2k.com/products/yb.php

cujet

I understand the need for "objective criteria". However, in this case, the 4.10 gears were just "stupid" with my setup, in my location. It was so absurd, this was the only correct solution, and because I'd done this before on my turbo miata, I knew exactly what to expect. BTW, that Miata ran mid-low 11's at 125-127 with either set of gears the 4.10's or the 3.63's. It too was better with the 3.63's. And, no my S2000 is not as fast. The Miata was considerably lighter and made as much HP.

Miahjera04

I will def be getting w/puddymod and going with the 3.63 fd. Just seems like the way to go for a street car in the 550whp range. Cant wait!!!!

VitViper

Must be an AP2 thing? My AP1 hooks 10-11psi on E85 (~450whp) in 1st gear, and hooks well over 500 in 2nd. Stock trans & rear end, 275/40/17 Toyo R1R's.