CRX mods

[StorminMatt]

Originally Posted by 101mpg

I see a lot about the D15Z1 swaps but am missing something important. What did it come out of? Why is it better mileage plus HP over the HF? I definitely want to do this right, and I know someone modified a CRX to get 85 MPG - so I know I'm on the right track on this one.

The D15Z1 seems to be the most popular engine on this board by a WIDE margin. Anyway, it comes from the 1992-1995 VX, which, like the HF, is designed to be a high fuel economy vehicle above all else. As for why it is better than the D15B6, there are a few reasons. One of the biggest if the fact that it has VTEC-e. This allows the engine to basically operate as an 8 valve engine (I say 8 valve because a true 12 valve engine has TWO intake valves per cylinder, and it is intake that limits flow) at low RPMs, and a 16 valve engine at high RPMs. This increases both power and fuel economy. The other advantage that the D15Z1 has over the D15B6 is the electronics. First off, the OBDI electronics used on the D15Z1 just return better mileage than the OBD0 electronics on th D15B6. Also, the D15Z1 has a lean-burn mode for improved economy, which the D15B6 doesn't have.

With all this said, you might wonder why the HF still gets a few more MPG than the VX, with its 'better' motor. The reason? Weight and aerodynamics. The CRX HF is both MUCH lighter and cuts through the air MUCH better. And it would seem that the difference is great enough to overcome the weaknesses of the D15B6 vs the D15Z1. So just think of what a CRX could do with a D15Z1 instead of a D15B6.

[GasSavers_Ryland]

I agree with the d15z1 civic vx engine, because of the variable valve timing, it can run more efficent at lower speeds and still rev high.
If you go with someing like a carbon fiber hood, make sure that it really is lighter first, alot of Ebay carbon fiber hoods are either steel, or fiber glass hoods with a top layer of carbon fiber, or sometimes even just dyed black fiber glass to give it that look, so be carful of what you are being sold.
For pulleys, lighter is alwas good, but you are not racing, so without your engine revving as high using an under drive pully setup will simply turn your alternator to slow.
I really like VX wheels as they are light, but they have an egg beater affect, if you can afford it you might check in to honda insight wheels, as they are nearly a disk, and light weight as well.

I have a set of Bosch +4 plugs that I stoped useing, in my opinion they didn't work well in a honda, they might work great in other engines, but I didn't see any increase, and went back to the NGK coper core V-power plugs.

[101mpg]

Okay - how much effort is it to swap in the VX engine? Bolt-in replacement? Wiring issues? Tranny issues?

Definitely looking forward to this.

[itjstagame]

Unrelated and not trying to steal the thread, but you're getting a 2nd gen CRX, right? '88-91? I think that's the only way to get any kind of useful engine options.

As for your last question I am very curious as well, was the VX and that engine considered 4th gen civic and fully swappable with all other 2nd gen crx and 4th gen civic engine/trans/axle parts?

I would think you'd be in for more work with the wiring since you'll have to contend with VTEC now too, but shouldn't be much more than you were looking at anyway.

While people seem to be answering questions I had my own, these engines are all great options, but what would you suggest if you had a 1st gen CRX? I would love a VX engine mated to a 2nd gen HF trans but I was told that not one single part of the 2nd gen CRX/4th gen civic drivetrain is compatible with my 1st gen. Is this really true? I mean even if I have to fabricate all mount points and use the hubs/spindles/suspension from a 2nd gen, is it possible?

I still like my 1st gen, since I like the smaller form factor and mostly the price :-), but it really sucks to have to use a 1st gen HF tranny (if I can even find one).


As for your idea to change gearing in the tranmission only and not just use an HF, I have to strongly suggest otherwise. The 5th gear in the HF is nice but not ALL that special .694:1 vs your DX .771:1, what you REALLY want is the final drive/diff, 2.95:1 vs 3.88:1, this is a HUGE difference and affects every gear. http://www.crxsi.com/specs.htm

Lastly does anyone know the VX trans ratios and final drive and if it will bolt right to any 2nd gen D series engine?

[mrmad]

You could swap a VX in a 1st gen CRX, but it requires custom motor mounts, different axles, a different fuel pump and lines to convert from carb to fuel injected (unless you start with an SI), and a mess of wiring changes.

WHen you're done, I think you'd have a better car - the 1st gens are lighter, and personally, I think they look better.

So basically, it's possible, but one heck of alot more work. There are some CRX websites that give this swap in a lot more detail then this.

Originally Posted by itjstagame

Unrelated and not trying to steal the thread, but you're getting a 2nd gen CRX, right? '88-91? I think that's the only way to get any kind of useful engine options.

As for your last question I am very curious as well, was the VX and that engine considered 4th gen civic and fully swappable with all other 2nd gen crx and 4th gen civic engine/trans/axle parts?

I would think you'd be in for more work with the wiring since you'll have to contend with VTEC now too, but shouldn't be much more than you were looking at anyway.

While people seem to be answering questions I had my own, these engines are all great options, but what would you suggest if you had a 1st gen CRX? I would love a VX engine mated to a 2nd gen HF trans but I was told that not one single part of the 2nd gen CRX/4th gen civic drivetrain is compatible with my 1st gen. Is this really true? I mean even if I have to fabricate all mount points and use the hubs/spindles/suspension from a 2nd gen, is it possible?

I still like my 1st gen, since I like the smaller form factor and mostly the price :-), but it really sucks to have to use a 1st gen HF tranny (if I can even find one).


As for your idea to change gearing in the tranmission only and not just use an HF, I have to strongly suggest otherwise. The 5th gear in the HF is nice but not ALL that special .694:1 vs your DX .771:1, what you REALLY want is the final drive/diff, 2.95:1 vs 3.88:1, this is a HUGE difference and affects every gear. http://www.crxsi.com/specs.htm

Lastly does anyone know the VX trans ratios and final drive and if it will bolt right to any 2nd gen D series engine?

[McPatrick]

I would love to see a step by step DIY sometime of someone putting a VX engine in a second gen CRX. I remember a thread on Gassavers.org but that one seemed to lack the end result and it does show some problems on the way.

My HF is just too nice to cut up and it hasn't 150K on it yet. As soon as I have the money though and find someone that is willing to do the swap for me for a reasonable amount of pay I definitely would like to get this "VX into HF swap" done. Ideally I would like an electric HF, but that is still way too costly.

There is also some mention in this thread about VX engines that you can pick up virtually free but I wonder if those days are over as people start to realize they're worth something because I haven't found the 'virtually free' ones yet.

By the way; I love your invention of the 'VRX' name and I think it would be worth fixing a good emblem for

[StorminMatt]

Originally Posted by mrmad

WHen you're done, I think you'd have a better car - the 1st gens are lighter, and personally, I think they look better.

Be careful with weight! Yes, the 1G HF is VERY light. But the 1G SI is actually HEAVIER than a 1988-1989 HF or a 1988 DX! And the 1G DX is really no lighter than the 1988-1989 HF. As far as looks, well, this os obviously a matter of personal opinion. But one area where I think the 2G CRX REALLY shines over the 1G is suspension/handling. I never really thought the 1G CRX was a very well-handling car. The 2G is just WORLDS better in this respect. And although you may think this is unimportant when it comes to fuel economy, that is not really true: the more you have to slow down to make a turn, the more gas you are going to burn to get back up to speed.

[itjstagame]

Originally Posted by StorminMatt

Be careful with weight! Yes, the 1G HF is VERY light. But the 1G SI is actually HEAVIER than a 1988-1989 HF or a 1988 DX! And the 1G DX is really no lighter than the 1988-1989 HF. As far as looks, well, this os obviously a matter of personal opinion. But one area where I think the 2G CRX REALLY shines over the 1G is suspension/handling. I never really thought the 1G CRX was a very well-handling car. The 2G is just WORLDS better in this respect. And although you may think this is unimportant when it comes to fuel economy, that is not really true: the more you have to slow down to make a turn, the more gas you are going to burn to get back up to speed.

Yeah, I haven't driven either 1st or 2nd gen, but looking at the difference in chassis geometry and why they made the changes, I am a bit worried about the 1st gen handling. It's even a shorter wheel base and is just supposed to feel less surefooted. As for looks, I do like it better, I like the shorter length and like the vertical door handles at the ends of the doors, I just think it's cool looking. But I think the 90-91 front end/headlights etc looks a bit cleaner, it just looks like a newer car instead of an 80s box.

As for weight, I'm really only using 1st gen DX because I have one and I only have one because the body was solid and it was $100 and I have a problem with saying 'no' :-). Only after the fact did I realize that none of the 2nd gen or really fun motors bolts in nicely. Anyway, it's about the same weight as an '88-'89HF, but most HFs I see are 90-91 and I'm a good 100lbs less weight. Plus I can always remove more weight, I'm already thinking of finding some 1st gen HF parts to install, like aluminum rear drums, etc (supposed to last longer and not rust up too).

Should I worry at all about the weight of the VX engine? I mean the carbed D series in the 1st gen are like 200lbs and the 2nd gen has a bit beefier suspension, would I be in trouble doing this and keeping stock suspension?

As for all that's involved with the swap. My harness is a shambles now and the head of my current engine is in the backseat and I really really do NOT want an automatic, so.... if I could find an engine that even had a hope of fitting, I'd put it in. The issue is money (isn't it always), I really need to hold out and find something $0-100. But if I found one of those magical VX engine/trans for free I'd definately pickup a VX harness, ECU, axles and go to town.

[GasSavers_Erik]

Originally Posted by itjstagame

if I could find an engine that even had a hope of fitting, I'd put it in. The issue is money (isn't it always), I really need to hold out and find something $0-100. But if I found one of those magical VX engine/trans for free I'd definately pickup a VX harness, ECU, axles and go to town.

I was able to find an HF trans for my 87 civic hatchback (1.5 CVCC) for $75. Just do a search for an 84 CRX 1.3 liter transmission on carpart.com

It increased my mileage by 4-5 mpg.

Be sure to use the felpro crush resistant head gasket if you put your CVCC engine back together. This gasket is reinforced in the center to eliminate the common CVCC D15 head gasket problem that occurs between cylinders 2 and 3.

[mrmad]

Originally Posted by itjstagame

Yeah, I haven't driven either 1st or 2nd gen, but looking at the difference in chassis geometry and why they made the changes, I am a bit worried about the 1st gen handling. It's even a shorter wheel base and is just supposed to feel less surefooted. As for looks, I do like it better, I like the shorter length and like the vertical door handles at the ends of the doors, I just think it's cool looking. But I think the 90-91 front end/headlights etc looks a bit cleaner, it just looks like a newer car instead of an 80s box.

As for weight, I'm really only using 1st gen DX because I have one and I only have one because the body was solid and it was $100 and I have a problem with saying 'no' :-). Only after the fact did I realize that none of the 2nd gen or really fun motors bolts in nicely. Anyway, it's about the same weight as an '88-'89HF, but most HFs I see are 90-91 and I'm a good 100lbs less weight. Plus I can always remove more weight, I'm already thinking of finding some 1st gen HF parts to install, like aluminum rear drums, etc (supposed to last longer and not rust up too).

Should I worry at all about the weight of the VX engine? I mean the carbed D series in the 1st gen are like 200lbs and the 2nd gen has a bit beefier suspension, would I be in trouble doing this and keeping stock suspension?

As for all that's involved with the swap. My harness is a shambles now and the head of my current engine is in the backseat and I really really do NOT want an automatic, so.... if I could find an engine that even had a hope of fitting, I'd put it in. The issue is money (isn't it always), I really need to hold out and find something $0-100. But if I found one of those magical VX engine/trans for free I'd definately pickup a VX harness, ECU, axles and go to town.

I looked into a 1st gen CRX before I bought my 90 HF and decided it was more work then I wanted to do to swap anything into it, so I bought the 90'. I would search the 1st Gen CRX websites, the swaps have been done before and they will list off the parts you'll need and how to do it.

As far as handling is concerned, I remember years ago borrowing a friend's 85 CRX and took it to Lake Tahoe from Sacramento. Coming back down the mountains there was some guy in a lowered 320i BMW who was trying to be quick through the sweeping turns on highway 88. I absolutely embrassed him in the CRX - maybe the Gen 2 handles better, but there's not much wrong with the 1st Gen.