87 CRX DX and HF differences questions...
 

Hi,
Ok, so what happened was that in my search for a HF, I looked at an 87 CRX that was clean, and rust free, and unmodded. (Why do kids do such terrible things to Honda's? but I digress.) As it happens, this one is a DX model with a broke timing belt. Now, what I'm trying to find out if I can get HF milage by swapping in the 8 valve engine and higher geared transmission? has anyone tried this? I know the DX is 150 lbs heavier, but if I start swapping the parts that help make the HF light onto this chassis, (Rims, brake drums, etc) can I get close to that weight? Is a same generation HF engine plug-n-play with the vacumn system? What about the transmission? Can I get any gains in the meantime with a just a HF ECU and/or Carb? I'm just looking around for some info while I start working this car into a MPG machine.
Thanks

I haven't come across anyone who knows much about the finer details of the controls for the crx hf but if you look at the parts list http://www.hondaautomotiveparts.com/...artsSearch.jsp and compare the dx and the hf you should get a clue as to what can be reused and what can not.
The hf of course has an engine that is tuned to cruse at a much slower speed, around 1,500rpm so the carburetor is not going to work from the dx, they are both lean burn engines but I'm not sure how the ecu differs or even how much it does other then working with the o2 sensor.
The first generation crx hf saved weight by not having sway bars, by having aluminum instead of steel air intake and filter box, half size radiator, light weight steel narrow steel wheels, no frills like passenger side mirror, clock, rear wiper, mud flaps, then they added a front air dam lip below the bumper.

If you are interested in the carburetor, intake and controls from a 1986 CRX HF let me know as I have them and have sold the car that they were spare parts for.

I'll just second the great advice Ryland gives on thr Honda Automotive parts site. I have been building comparison parts lists for a possible conversion of my own. I have been surprised by how many parts can be re-purposed. The diagrams and parts numbers are great for reference. Good luck. I wish you success! And keep us posted please.

i don't know about the carbed engines. The later D series engines, which were all fuel injected, I know a lot more about.
I think the D series started in 88.

The D series engines were used in 86 or 87, but they weren't really the same D-series engines that were used later.

First-generation CRXes (1983-1987) were all carbureted except for the Si models (85-87). So the standard (often called the "DX") and the HF models were both carb'ed. I don't really know most of the differences between the first-gen DX and HF models.

The 2nd-gen CRX ran from 88-91 in the US (some 92s elsewhere). All were fuel-injected; the standard (DX) model used Dual-Point Fuel Injection (two injectors at the throttle body only) while the HF and Si used Multi-Point Fuel Injection (one injector at each intake port). The HF only had 8 valves with roller rockers; the other two had 16 valves with plain rockers.

The 2nd-gen HF had the tallest gearing of any D-series Civic. Not only were the individual gears tall, but the ring and pinion ("final drive") were also tall.

Swapping an injected motor into a carbureted chassis is not straight-forward. At the very least a fuel return line must be added, which is not that easy to do except if you do a hack-job. The wiring changes would also be quite extensive for that swap. Not to mention you have to fabricate mountings and possibly re-locate mounting points to swap an 88+ motor into the earlier chassis.

Swapping between carbureted 1st-gen models is probably easier, but I don't really know. My guess, if you can get everything installed and working correctly, is that you'd get close to HF mileage on the freeway, but not as good in town. Weight generally makes more of a distance in stop-and-go driving than in steady-state freeway driving.

-soD

actually, the D series engines were ALWAYS injected. the 86/87's with the D series were Si only models, and were injected.

The Integras from 85-89 were the D16a1. DOHC, 120 or so horsepower. I currently own one - was considering using the motor/trans for the trike project.

The E series engines were the old carbed engines. I don't know if they ever was an injected one - I've never seen one if there were in the US.

If I were looking for an older civic, I would really look for one with a D series engine and fuel injection. IN particular, the multi port is better injection then the TB, but the TB is a lot better then a worn out carb.

Don't be afraid to look at the 86-89 integras. Decent cars, and more room then the civics.

Personally I would only get the DX if it was a solid body, not rusted out at the jack points, or where the pan hard bar bolts to the body, rear fenders are also a pain to deal with if they are rusted out, front fenders on all of the first gen CRX's are plastic and you can get new, reproduction fenders but I don't know where, everything else about the first generation CRX's engine is pretty much only common to those 4 years of CRX's, swapping in an engine from another year is an investment in time and money that most people are not willing to undertake and for good reason.
Even with the CRX DX you should still get 40+ mpg if everything is running right and you can always start with easy simple stuff, like 14" Honda Insight, Civic Hybrid or other light weight narrow smooth 4 x 100mm wheels with low rolling resistance tires (main reason for 14", 13" LRR tires are difficult/impossible to find) and then swap other parts as you have the time and money, you could even skip the HF engine block and just swap head, intake and carb, main reason for the HF block is different pistons/rings, then the transmission swap is pretty cheap and easy.

Alright,
Thanks for the help and input, This particular car has a frame and interior that doesn't look its age, so that helped sell me on it. (That, and the fact that it might have been an HF model,) So anyway, I'll try and pull the head in the next few days to get it back on the road, and find a vacuum gauge to install in it. And then look at finding parts to lighten this one up. I'll end up looking into the head swap as well, but I thought that the 1st gen HF's had a 1.3L? I've also read that they had 1.5L. I do plan to stay close to stock, as in "I'm not planning to swap in a VX engine" just yet. (probably do that to the wife's 90 DX hatch, first.:)) Anyway, I want to just do what it takes to match the 1st Gen CRX FE, and I think it's going to pretty darn hard to find an HF that has been taken care of, so I'll see where this project leads.
Thanks guys

In 1984 there was the CRX DX 1.3 and the CRX DX 1.5 and that was it, no other trim level designations, the fallowing year was the first year of the HF, and it has a 1.5 litter engine.
If you ever find a CRX 1.3 buy it as I think their EPA numbers were in the high 50's to low 60's.

As I said before, I have a whole intake, carb, controls, aluminum air box and so on from a CRX HF if you decide that you want to go that route, it all came out of a running car that some kid was doing an engine swap on, I put the engine block in my CRX HF before selling it, if you decide that you want it let me know and make me an offer.

I think I misread a webpage about the 1.3L, Just because I didn't mention the carb and airbox and stuff the first time, well that doesn't mean I don't want it. I think I almost have the post count to PM you, so I'll do some price checking, and shoot you a line.