I'm sure this has been talked about before, but I searched and nothing came up so...
I am in need of a new tranny for my 90 Civic Hatch. So info about my performance so car. I'm running a D16A6 with DX tranny. SR intake, 421 header, custom 2.25 piping to Dynomax muff, short throw, and Royal Purple fluids. My best is 15.780 @85 on lame street tires at Southern Oregon Dragway (not the best track). I just purchased an ACT heavy duty 6 puck clutch, 7 pound Fidanza flywheel, Nology hot wires, and Denso Plugs. I'm looking to put all these on with a new tranny.

I have another hatch that has a DX tranny in great condition (approx. 60,000 easy miles on it) which I can swap with my slightly grinding 200,000+ miles DX tranny, but I'm in search of performance. So I'm thinking of spending the 500 bucks for a 30,000 mile Si tranny from Japan. But I'm not sure if it is worth spending the 5 bills or not.

Does anybody know the difference in times between the Si and DX tranny alone? Like would just the tranny swap get me a tenth in the 1320? I've heard from some people that it could get two tenths, but I'm not really sure. And I mean this is 500 bucks that could go toward other go fast goodies.

Also how about a limited slip? I am looking to take my car road racing and autocrossing and I know the advantages of having a limited slip, so should I go with a DX tranny and use the 500 to get a limited slip as well? Or is the Si tranny still better than a DX with limited slip?

Please share your wisdom, thanks.
Later,PDX

 

If the tranny is from a jdm si then its a zc tranny..Which is better then our si and dx trannys..But dont pay 500 for

..Get it from hmotorsonline.com for $100..Click here

 

I think the si tranny has shorter gear ratio which means quicker acceleration probably would be alot more beneficial since your not putting down too much power

 

the only difference between si/dx tranny is final drive everything is the same so if you wanna save prolly less the 0.10 on your 1/4 then go ahead and do that personaly i would get the dx tranny with 60k and spend the 500 on a lsd......better then that would be go hydro and get the jdmd15b tranny with lsd thats what i did but if i could go back i would have kept my dx tranny and spent money on a lsd

 

Si has a 4.25 final drive
DX has a 3.88 final drive

Otherwise, the 1-5 gears are the same.

There are a couple ZC trannys...the dohc version has an aggressive 1-5 but relatively low 3.88 final drive. This is the one most people are talking about.
Its performance is on par with a Si tranny.
There is also a sohc ZC tranny that has the same 1-5 as the Si/DX but the final drive is an insane 4.4

The best of both worlds is to take a dohc zc 1-4 and match it up to a Si 5th and final drive. Easily the best all around D-series tranny for a naturally aspirated setup.

And it may sound stupid, but if you have access to PS1 or 2 and Gran Turismo (just about any version) you can purchase the custom tranny option and custom tweak gear ratios/final drives....then go drive them on a straight line test track. All other things being equal, you can see how the difference in ratios impact performance.