Can't find a VX, D15Z1 swap into CRX shell?
 

If I can't find a VX to hypermile, then I'm going to have to make something better!

I've seen on here a couple of thread regarding putting the D15Z1 into a CRX, usually using the stock VX/CX trans. According to https://www.knology.net/~jediklc/gearratiosdseries.htm the CRX HF transmission is the tallest geared, and if I'm losing weight with this body swap (hehe) then I might as well be geared taller. Can this engine bolt to this trans? I know it lacks a VSS, but I can get around that with some creative electronics I think. But mechanically, will it bolt together?

Thanks,

Dale

Yes it will bolt together, but you need to know that the difference is .026 taller gears on the federal HF. That is equal to going from 165/75/13 to 175/75/13 tires. Why go through that hassle? CX trannys with VSS are abundant. The final drive ratio is a multiplier. not such a big difference when you actually do the math.

I see, after going over the math a few times, it'd only save me 158rpm @ 60mph. I'm going to take a stab and guess that finding a taller gearset to drop into any one of the transmissions is impossible? :P

but the stock CRX tranny is going to bolt to the cars engine mounts, where the CX tranny is not, and then you have to go from a cable clutch, to a hydraulic clutch, I would lean towards swapping just the engine, not the whole drive train.

Thanks Ryland and soletek for the info thus far.

So, if I understand this right:

Gear-wise, not a big difference either way.

Mechanically, keeping the CRX trans is simpler since it'll bolt on, and I wont have to change the clutch system or motor mounts.

But I'll have to hack the transmission to send a VSS signal to the ECU, or leanburn wont work properly (and probably other stuff)

That sum it up?

If so, I'm leaning towards keeping a CRX trans then, since I'd rather play with electronics than weld up motor mounts and fiddle with the clutch.

Now to A) come up with some money (I hope my 94 maxima sells!) and B) get a CRX shell and trans :)

If you end up making a mod to support the VSS in the CRX tranny, and you get it to work properly, please post in the How to/DIY thread. I'm sure many people would like to know. I went the other way because a mechanical to hydraulic clutch conversion kit exists, and since I'm a machinist, motor mounts are not so tough. The final drive ratio is not the only difference between the transmission gearing, I don't know how lax the parameters are in the ECU to compensate for these variations. If the car bucks, jumps, and acts like it's hunting I guess you'll know. Keep us posted, it sounds like fun.

Bye-the-way, where are you located? I run across CRXs from time to time here in NorCA. Again, good luck!

I'm (unfortunately) located in Oklahoma.

I can't imagine having any trouble making a converter (famous last words?)

The VSS just uses a series of pulses to send speed information to the ECU yes? If so, it should be easy to read the RPM of the speedometer cable with a digital encoder and have a little $2 microprocessor convert that into neat pulses...


Speaking of cheap modern microprocessors, it is eventually my goal to hook up a bunch of nasty wires to my ECU harness and monitor everything it does... so I can build my OWN scratchbuilt ECU for it. Once I understand how to operate the engine, control the V-tec, etc, should be possible to construct such a thing, and it'd have alot more versatility than the stock ECU...

Definitely go for it! Then, let us all know what to do.

Soooo, just found out today a friend of mine has a 2nd gen CRX for sale, in full race trim, uber lightweight (stripped), turbo'd, etc. He's looking at ~$3k for it.

I dont have that, but another friend of mine really wants the engine and transmission... and I also have a 300zx to sell to raise some cash.

*crosses fingers*

Couldn't get much better, a super lightweight shell with adjustable coilover suspension, beefy brakes, lightweight wheels... *droooools*