CRX HF or '79 Civic?
 

Hi everyone, I have a D15Z1 from a Civic VX to swap into either my '91 CRX HF or my '79 1200 Civic.

The HF weighs around 2,000 lbs., has some rust issues that will need to be addressed before it's driveable and it doesn't look very good.

The Civic is in fairly nice shape with no rust issues, weighs around 1,500 lbs. but has the aerodynamics of a brick.

Which one of these cars has the most potential for ultimate MPG assuming they each have a VX engine, HF transmission and are otherwise fairly stock?

Thanks for any advice, this is a great forum.

I've install a D series in my 78 civic. Its ALOT of work! You need to know how to weld, machine, fabricate, and be able to wire.

Here is a picture of my 78. I'm going to "attempt" to install a B16 this winter.

That swap looks great, nice job. I realize the amount of work, I've done a couple Fiero swaps so far and am in the middle of my third-a Northstar in an '84 Fiero.

Fabrication and wiring is not a problem, I enjoy that sort of thing but I agree that swapping this engine into the CRX would be 100 times less work.

Work and time aside, what do you think would be better overall for mileage?

I think you should do the 79. If most of your driving is in town, the aerodynamics wont be an issue. Long trips in an old (79) civic arent very appealing to me. IMO

Also remember that the 1979 Civic is not going to have a high pressure fuel system to run EFI. This can be quite a pain in the butt to deal with even on something like a 1986 CRX, which DOES have the SI varient from which to swap the fuel system. But since NO 1G Civic EVER had EFI, this is going to ave to be 100% custom.

That's a good point, I should have mentioned that it's a '90 HF so the swap is even easier. Basically I'm wondering if the .29 cd of the HF will make up for the added weight. I do a lot of highway driving so I'm shooting for over 50MPG combined.

You could also sell your 1990 HF and get a 1988-1989 HF. That will drop your weight from 1967 pounds to 1819-1834 pounds. And the D15Z1 swap will be no harder.

How about 1st gen HF?

Weight close to the '79 with better aero and (relatively) easy swap. Low pressure fuel would have to be addressed, however.

A 1G CRX would not be a bad choice. After all, the fuel issues can be taken care of by swapping parts from the 1G SI. But is one other issue to contend with. One is wiring. The wiring changes wil be VERY extensive, as this car has no wiring for EFI. Furthermore, all of the wiring will have to be custom, as there are no wiring kits for this swap. And if you have to pay someone else to do it, I hope you have LOTS of cash.

Then, of course, there is the transmission to deal with. Strictly speaking, this is not much of an issue, since a 1G Integra transmission can be used with little problem. BUT, I am assuming that you are doing this swap to get better fuel economy. And if this is the case, the Integra transmission is rather short. If you want to use, say, a 2G CRX HF transmission, there will be mountng issues. Specifically, there are no mounts available to make this a bolt-in swap. Unless you can weld/fabricate, or pay someone else to do so, this is just not going to work.

My thoughts? This seems like an awful lot of trouble to save ~100 pounds (compared to a 2G HF).

I would go with the HF you have since the aero is good for the highway, unlike the 79. A CRX of that gen can also be a very comfortable cruiser since they come with comfortable seats, and decent interiors (unlike the older ones in my opinion).

Thanks for all your help everyone, I think I'll go with the CRX. I've started repairing the rust and it's going well so I think I'll drive it as is to see what the mileage is like then swap the motor later on. I'm interested to see the improvement with the new motor in the same exact car with the same transmission.

what sort of mileage does the '79 civic get as it is? I would think it would be decent, seeing as how it has a 1.2L engine, if it has a automatic, or the 4 speed, then I would swap in a 5 speed, and I suspect that the 5 speed FE tranny from an '80-83 might be to differnt to drop right in, altho it would be worth checking on, there is one in Portland OR with 93,000 miles on it for $150 from a 1979 civic.
If you are looking for more power, I've seen photos of older civics that people have put muliti thortle body fuel injection setups from motorcycles on, as it sounds like you have some expearince with fabricating, and making things work.

I've only driven the Civic about 500 miles and it got 36 MPG mostly highway between 55-70 MPH. It has a 4 speed but I believe a 5 speed from a CVCC of the same vintage would bolt in. I think I just got lazy being that the CRX is the easy way to great FE.

If you pick the CRX HF it would be great if you could document the whole transplant as there are more HF drivers here that will consider putting a VX engine in at the point their engine gives out I think (like myself even though that can be a while since it only has 148K on it now).