VX -- Del Sol engine swap
 

Newbie questions--

I was thinking of a Civic VX for gas mileage but the car is so plain-jane (although pretty) and I only need a two-seater. Since VX engines seem to be pretty available I was thinking about dropping one into a del Sol, which I really like, if I can find one with a blown-out or high mileage engine.

I've seen a lot of Honda expertise on this site and wanted to ask about the potential for making an engine swap. I've done lots of work on cars and motorcycles but have never swapped an engine (and will be paying someone to do this one) and have never owned a Honda automobile so I thought I would ask some experts.

I understand that mechanically the D15Z1 engine drops straight in to all the del Sol models but I'm not sure about other stuff.

1. Do I need to replace the entire ECU or can I replace just the chip(s)?
2. Can I go with a non-VTEC del Sol S and keep its wiring harness but run the VTEC wires separately, assuming I can break into the harness connectors?
3. What else is going to bite me in the ?

thanks from the new guy,

Matt and I were making fun
 

Matt and I were making fun of the del sol vx in your profile, but I ended up being correct about the swap, he thought you were confused. Haha, no offense of course.

The D15Z1 will not drop into any del sol, some del sols had a b16 in them, which has different mounting stuff, get the del sol s, lightest stuff. (you could also consider a crx, :p)

The ecu question depends on what ecu you have and how you plan on running the engine. You could go the stock route, or have me chip a p28 for you or something to run the maps, then tune it, which would be peachy also, better than stock for sure.

Going from non vtec to vtec is just a pain in the ***, you'll have to wire up a bunch of crap, but matt'll know more about that.

And finally, I ain't done a swap yet, but we could always meet up and do it ourselves, since I'm nearby. Good luck and welcome to the site.

Hey Moses... A few things
 

Hey Moses...

A few things you're going to run into:

The computer will be different for the d15z1. The z1 uses a p07 ECU. The p07 ECU is slightly different than other obd1 Honda ECUs. This being said, you'll have to make a few modifications to you existing wiring harness for it to work properly. One obvious difference is the fact that the z1 engine uses a 5-wire wideband o2 sensor, where the del sol uses a 4 wire o2 sensor. The existance of vtec is another difference. You can wire most of these up directly, but it takes a little bit of work and lots of patience.

If you really want a two seater that gets good gas mileage, I'd suggest looking to swap the z1 into a 88-91 CRX HF. The HF is lighter and has a longer geared transmission (for better gas mileage). You can bolt the z1 up to the HF transmission and use a specially made conversion harness for the wiring issues. These harnesses usually cost around $150, or you can make your own if you like soldering. I have the pinouts to make your own.

One thing you're going to have to be cautious of is the transmission you use. The VX Transmission is hydrolic and is very long geared (good for us). I'm certain that most Del Sols are not as long geared but are also hydrolic. If at all possible you want to find the engine with the transmission. It will save you a few MPG in the long run. If you choose to put it in a CRX, you want to find a HF transmission. This is what I'm doing for my 89 sedan.

For an engine, if you have the money to spare I'd recommend getting one from an engine importer. I bought my engine for $350 plus shipping. It is the japanese equivilant of the z1 engine, but it has less than 60k miles on it. Good luck finding a US engine with that few miles on it.

ANyway, I'm ranting now.

I'm doing the same swap in my sedan, so I've learned a lot about the z1 engine and the civic VX. I'd be more than happy to help you along the way. Just stick around and post any questions you have.

Just FYI, the lightest Del Sol is the 1993 S Manual Tranmission, which weighs 2277lbs. The Civic VX weighs 2000lbs. If you can find a 88 CRX HF it weights 1819 lbs.

400 pounds will make a big difference in acceleration, mpg, etc. A friend of mine put a z1 engine in a 88HF and with some weight reduction manages to get about 60mpg.

See stock honda weights here:

https://www.honda-tech.com/zerothread?id=403871#4156615

ANyway, I'll be sure to help you any way I can.

Oh, and hondas are really easy to work on, so don't let them scare you :)

Quote:One obvious difference
 

If you don't want to deal with this, you could run a chipped and tuned p28, also. I'm setting up a p28 to run a 4 wire with someone's d16y5 (civic hx, newer version of the vx) right now actually.

The cx transmission is exactly the same when compared to vx, so either will do.

Good luck, found the engine already?

Re: Quote:One obvious difference
 

Don't forget that one of the reasons the p07 ECU (and civic VX) is able to give good gas mileage is because of the wideband o2 sensor. The extra range allows for much more exact air/fuel ratios. It's like being perfectly tuned all of the time.

Re: Quote:One obvious difference
 

But then again, do not forget that on a good tune there is no need to run an 02 sensor at all.

quick thanks
 

Wow, thanks for the fast and detailed responses, even if you were laughing at me :-) It's going to take me a little while to try to sort out some of the stuff you wrote, I don't know one ECU from another and I've obviously been misinformed about some of the mechanical aspects of the swap.

I wanted a CRX, I love the looks and the layout and knew about the weight, but really don't want to be fighting rust and other old-age disabilities from the day I buy the car. I can theoretically get a del Sol as recent as '97, going on 10 years younger than a CRX, worse since the CRX's got heavier as the model years passed. Plus since this would be a winter car in central PA I would really like to get anti-lock brakes, so it looked like a del Sol even if CRX's had my heart. Even if the del Sol's (and other recent cars) are relatively heavier, at least they are shorter than other Civics, and I like the small exterior size. Of course finding ABS on the S model is not going to be easy, especially on a car cheap enough to make the enging swap not totally stupid. I think ABS is stock on the DOHC VTEC, and I've seen it on SI's but not many S's.

I'm not too worried about the gear ratios, this car would probably not see much highway driving and for the rest of the gears (except 1st) the driver gets to pick the ratio, I'm only thinking manual transmission. But what's a hydrolic transmission? Are we talking about cable vs. hydraulic clutch? That I understand, but if this is some weird hondamatic transmission, it's another thing I don't know anything about.

I haven't picked out an engine, it's more like I noticed that one seems to come up on Ebay regularly and there are a couple of importers that sell them surprisingly cheap. More importantly I also haven't found a chassis, not a lot of Hondas with blown motors I guess. I still don't know for sure if this project is just too stupid to do. Probably is. It would just be so cool, much cooler than an Insight, which any fool can buy.

Do the 5 wire O2 sensors fit the standard threaded hole in the cat? IF so it's just a matter of getting the wires up to the brain, right? A p28 ECU normally uses a 5-wire O2 sensor which SVO is making work with a 4-wire? While I would always prefer to avoid work, one thing I can do is solder. I build electronics in a research lab, I know how to hack a cable. If I get a chassis and an engine then I'm definitely light the ECU, 4 or 5 wires.

thanks again for the support.

Quote:Are we talking about
 

Yes, but that also applies to the transmission. Hydraulic clutch goes with hydraulic transmissions and such.

p28 always uses a 4 wire, cannot be made to use a 5 wire. It's nice because it can be tuned and has vtec, whereas a p07 (stock z1 with 5 wire) cannot be tuned.

Re: quick thanks
 

if this is a project you're serious about, I'd consider looking for a CRX with little or no rust. They exist. I got my 89 Sedan with hardly any rust on it. If you are willing to travel to get your car it's even more likely that you can find it without rust. Not only this but you are much more likely to find a CRX shell with no engine. The odds of finding a Del Sol shell is really low.

My bad. SVO already corrected me. It's a hydrolic clutch. All of honda's cars after 92 were hydrolic lutch. For the VX Transmission to work in my car (pre-92) I would have to convert to hydrolic clutch, which is not worth the effort.

I agree with you on this one. You also might want to look into an engine from a Civic CX (8-valve gassaver) or a Civic HX (1.6 L version of the VX engine).

The o2 sensor on the hondas actually screwed into the exhaust manifold, not the cat. I think the b-series engines have two o2 sensors, but the d15z1 has only one and it is on the exhaust manifold. The hole is the exact same size for 1 wire, 4 wire, or 5 wire. It is just a matter of connecting it to the ECU, so it isn't that big of a deal at all. I'll let you know how it goes when I do it on my car. I'm going to have to wire 4 of the 5 wires myself as my car currently only has a single wire o2 sensor.

As for the ECU, I purchased mine for $30 online. The p07 is not desired at all by the racing community ,so they often ditch them. For the z1 engine you'll also need to have an EGR box. I'm not certain if del sols had them or not, but I think they did. You can use one out of a CRX HF from a junkyard too.

If you really want a CRX I say go for it. Not only are they the new hotrod, but there is a huge support community for them. They have tons of aftermarket parts and look pretty cool. It's pretty nice when a late 80s car still can look new two decades later. I would be much more able to help you with this swap if you went the CRX route as it is the same generation as my car.

But the trick is to find a 88-91 CRX with little or no rust. I think it's possible, and can be very cheap if you shop around.

Quote:I'd consider looking
 

You mean like mine? Rust free, :)

I didn't mean to correct you, I didn't think I was at least. If you go crx you must use a cable clutch though, so consider that, hf (cable) tranny is the longest geared anyway.


When looking at your options, CX engine = 70 hp, VX engine = 92 hp, D16y5 HX engine = 110 ish I think? VX will get the best gas mileage though.