is it a worthwhile swap performance wise?

i know it feels a bit torquier with the 4.25 fd but does that actually translate into faster 1/4 mile times or beating cars that you wouldnt have beat before?


im considering this swap for my next mod but id like to hear what people think first

 

Overall, IMO the DX tranny is the best because its not really short or really long. Its inbetween. If I were you I'd put my $ elsewhere on the car.

Blaze

 

This is a good topic, because I am dropping a '91 Si motor in my car next weekend. I have an '88 DX Hatch and wondered if sticking to the DX tranny would be a good idea and provide better gas mileage and lower cruising rpm.

I have both trannies so I guess if I didn't like one I could switch to the other.

Is the Si tranny any more durable than the DX. I am thinking of turboing my Si motor next year so I don't want a weak tranny in the car.

 

bump this one up, I want to know as well.

 

very interesting question, keep this one at the top until someone answers it. Can a DX transmission handle the output of a turbocharged engine. you can find dx trannys at any junkyard for significantly less than the rare si tranny. I would imagine the dx trannys aren't too abused also. has anyone heard of taking the final drive from a si tranny and placing it into the dx tranny? Would this even work?

 

From what I have heard the Si trannies are actually stronger but I dont have anything to back that up with only what I have heard.
As for taking out the final drive and putting it into to DX yes its possible there are a few posts about it on here that I have came across here and there. There is also someone that did it (Again cant remember who) but he made a post in one of the topics about it.

 

Here is the link for the DX-Si Hybrid tranny.
https://honda-tech.com/zerothread?id=536764
*EDIT* this is also where it says about the Si bearings being bigger than the DX ones. There is more just cant find them right now.

 

I think it is hard to say, I have a STD 4 spd tranny on my 88 hatch, with a greddy kit, and it pulls nicely!! I have a hard time launching it because it just rips the tires up and spins crazy!! The gears are long and it's good with boost, but I sometimes wonder if an SI tran would have better acceleration.

 

as far as the myth about the Si tranny being stronger, i dont belive it one bit. My brother has a 91 DX tranny and an 88 Si tranny, the casings are exactly the same. I doubt that honda would use the same casing for totally different internals, but i could be wrong.

 

I ran 9 psi on my stock DX trans with no problems. I recently converted over to the Si tranny and it feels much more responsive. This is especially beneficial if you live where there are nice, tight curves and hills, or if you enjoy roadcourse. The gearing is shorter and allows a quicker 1320 as well. Worst case: you don't like the way it feels and have to spend 2 hours swapping back to the DX.
As far as strength goes- keep in mind that with the Si tranny you're putting more torque on the axles and less on the transmission due to the lower gearing. This being said- theoretically the Si could even be weaker and still hold up, so long as the axles could handle the added stress.

 

for all motor? yes its way worth it. it made a .5 second difference.

 

Theres not doubt in my mind that the SI tranny is superior both strength, and performance wise. I had the 1.5 stock dx motor with the 4 speed tranny, swapped in the 91 si, and felt the diff imediately. The gears are shorter-better/faster acceleration, and obviously the tranny would have to be made somewhat stronger considering the motor your pulling it off of. No, the si, with its 1.6 mpfi isnt doing any great feats, but keep in ming that a bigger motor requires a stronger tranny or there is a flaw in the system. Go si all the way !!

 

for a cheep fix could i get the 3 gear syncro out of known working a dx tranny and throw it into my si tranny? I am sick of the grinds and I really don't feel like spending money on the rebuild kit?

 

IMO, the SI tranny is worth the swap. Suggestions from previous posts tell us that even turbo d series engines gain a better 1/4 mile run using a SI tranny, than a DX tranny.

However, the downside is that SI transmission are hard to find for low prices. When I bought my Crx its transmission wouldn't go into 2nd, so I had to swap for an HF(came from a DX though). For six months I searched, looking for a decent priced SI tranny(75-200), and for one within my area(since 3 people I tried to buy from would give me excuses for not shipping).

I finally found one, and it was all worth it. From the HF it was like night and day. The car pulled harder and I always had a gear to downshift into for the powerband.

Point being, if you can find a good SI transmission for less than $200(including shipping) its worth the upgrade.