The 5spd isn't any more reliable than the 6spd. You would be fine with either tranny. The choice would be with which tranny would put down the power best and where the shiftpoints fall.

I'm building a car for roadcourse yet, but I am using a full k20a2 setup + tranny in my 98ex. My concern for your build would be hooking up the tires with the torque from the k24. The longer gearing from the 5spd may be what you want.

 

Thanks for the information. I'll be using gear-based boost control and running on R-comps, so I think that I should be able to keep from spinning the wheels. The torque curve should be very flat (roots type supercharger), which helps a lot. Back when I ran a turbo I had a lot of problems with traction, but since switching to a supercharger it's much easier to keep it under control.

 

I'm running a s/c K24A2 and doing some road course stuff. Still learning how to really drive (still doing NASA HPDE's) though so I'm not sure I'm the best example, but what I'm using the the 5 speed from the A3 5 speed with the taller final drive from the A2 six speed.

With that setup I've never run out of gear in 4th even coming down the pretty fast back straight at Road Atlanta, and I've never needed any lower than 2nd on an autocross course.

As an added question, how are you planning on getting 400whp out of a blower 2.2? I've got IPS building me a 2.2L destroked K24 and I hope to get 350 out of it, but may not.

 

The 3rd Gear (syncros) in the K20a3 Tranny is quite weak isn't it?

 

The 3rd Gear (syncros) in the K20a3 Tranny is quite weak isn't it?

A damaged synchro is most likely a sign of a bad driver. Too many people abuse their trannies.

 

I'm running a s/c K24A2 and doing some road course stuff. Still learning how to really drive (still doing NASA HPDE's) though so I'm not sure I'm the best example, but what I'm using the the 5 speed from the A3 5 speed with the taller final drive from the A2 six speed.

With that setup I've never run out of gear in 4th even coming down the pretty fast back straight at Road Atlanta, and I've never needed any lower than 2nd on an autocross course.

What is your mph going down the back straight on RA? That track is what made me decide to swap in the K. I got sick of getting a lead on people going into turn 7 just to have them eat it up on the back straight...

 

The 3rd Gear (syncros) in the K20a3 Tranny is quite weak isn't it?

If any of the gears in the A3 tranny is bad its usually 2nd gear that goes, but I've got over 80K on my tranny with no problems and just routine maintenance.

What is your mph going down the back straight on RA? That track is what made me decide to swap in the K. I got sick of getting a lead on people going into turn 7 just to have them eat it up on the back straight...

I've hit an indicated 140mph, but more could be had. Thats with me bogging a little in 3rd coming out of 7 when I really should have been in 2nd plus I'm a pansy and have a hard time staying in the throttle all the way to the braking point. A better driver could probably get a good bit more out of it.

 

I haven't been to RA yet, but on the straight at Roebling Road I hit 160 before I run out of gears. I'm not sure if I need to go faster than that, pretty much nobody is catching up to me at 160.

 

I haven't been to RRR yet, but I'll be there 05/19 and 05/20.

 

It's a lot of fun, a fast and relatively simple track without a bunch of walls or other barriers, and no significant elevation changes. If you hit the last turn right, then you can enter the straight (over 1/4 mile long, wide and flat) at over 100, and I was topping out at 160 well before the braking zone.

I plan on being at RA in June if I can get my car put back together before then.

 

Hey buddy, depending on what you're revving to I think that the K20a2 trans with the 4.388 final if you're using ~205/50/15s

With 205/50/15s and a 7500 revlimit 6th gear is going end at 159. If you rev to 7800 your 6th gear will end at 165.38 with 205/50/15s

I think that will be your best option

Lemme know if you need any further help

A2 trans is red
http://www.fatboyraceworks.com/gear...idth_2=205&TireAspect_2=50&RimDiameter_2=15&Calculate=Calculate/Graph&Compare=1

 

Thanks, that calculator is pretty handy. I'm running 225/45 15's.

 

If you need custom trans builds I may be able to offer some assistance.

 

A damaged synchro is most likely a sign of a bad driver. Too many people abuse their trannies.

This is so true. I've been running the same transmission for 3.5 racing season with no problem.