Getting the most out of an 86 Civic Si
 

Ok, so Monday I am going to pick up this:

https://www.fuelly.com/attachments/fo...812c49c6ac.jpg

It still has the original engine (EW4) in it. I suspect that the way it is right now I'd get 35-40 mpg with it. I seem to remember however that another Gassavers member had put a VX engine in an older Honda but cannot remember who or if this was a third generation Civic.

Do you think I could macth the EW4 engine with a tranny from a first generation CRX HF and if yes, would this improve overall mpg at all?

Yes- the 84 CRX HF tranny will work fine in your car- thats what I did with my 87 Cixic DX (1.5 liter carbureted engine). You can look at my gas log and see when I switched over (over 1 year ago).

Its much quieter on the interstate (only about 2200 rpms at 65 mph) and I can get 41-42 mpg at this speed during the summer months.

After the whole debacle of swapping an HF transmission to my Civic DX (which netted ZERO mileage increase and made the car ALOT more sluggish), I'm kind of down on taller gearing. I wold seriously suggest that you leave things as they are. Or if you want something more economical, consider selling the car and buying a CRX HF.

@ StorminMatt: what year is your Civic DX from?

I would like to know what generation too. i have a 94 civic dx, dx motor with EX/SI tranny. im at 2000 rpm at 48mph, 2500 rpm at 60 mph, and 3500 rpm at 80 mph. I have been thinking of a cx/vx tranny for a while, but i drive alot of city miles though

That body style looks really sweet with VX wheels, stock size tires are 175/70 R13" and 155/80 R13" work and be narrower without screwing with your spedometer this will give you less unsprung weight, lower rolling resistance and all that other good stuff.
If you check on Redpepperracing.com there used to be a guy making carbon fiber hoods, fenders, and other odd parts for the 3rd generation civic hatch backs, and at a reasonable price compared to what some people sell them for, that site also has alot of other tips altho they are all geared twards racing and some of the people on there are full of them selves, because speed is where it's at.
I would check on gear ratios for all the trannies avalible for that year (1984-1987 I think all work, other years get a little skechy), but an HF tranny should work without bogging you down to much and a DX might be better grearing then the SI, but I can't say for sure as I don't have that spec sheet in front of me.
About your engine wikipedia says "The fuel injected EW3 and EW4 produced 91 hp (68 kW) @ 5500 rpm and 93 ft?lbf (126 N m) @ 4500 rpm."
Synthetic oil alwas worked well in my 1984 civic DX, in both the engine and tranny, and the tranny is often overlooked.
That is all I came up with off the top of my head, unless you want to remove the power sunroof, appearently it's really heavy, and takes up alot of head room.

Yes, I already have started reading quite some threads on RPR and it is definitely usefull, There are informitive threads and parts for sale even though like you said it is focussed more on speed where we focus more on saving gas here.
Do you have any pics of the 3rd gen Civic bodystyle with the VX wheels. Would love to see one!
Oh and by the way; this Civic (and none of the Civic Si's) does not have a pwoered sunroof. It's a popup glaspanel that can also be taken out, so I don't think it is as heavy as for instance the powered sunroofs you will find in the CRX Si's of those years (first gen).

The Civic is a 1989 DX HB. Mileage has NEVER been overwhelming on this car for whatever reason - only about 33MPG on the freeway. For comparison sake, this is no better than my ITR-powered CRX, which happens to boast 200HP and can roast late-model Mustang GTs alive. Oh, and it runs at something like 4800RPM at 80MPH. I should also add that the original transmission in the car was not a DX transmission, but an SI transmission. So you would THINK that the HF transmission would help. It didn't.

As for swapping a VX transmission in your Civic, I would certainly be hesitant after my experience. BUT, if you can get the transmission cheap AND swap it in yourself, it might be worth trying just for kicks. In my case, I got the transmission for $40 and installed it myself. So it's not like I lost big time doing this swap. On the other hand, if most of your driving is in the city, you are probably better off with what you have. The taller fifth gear could possibly be helpful on the freeway. But the rest of the gears will possibly be detrimental in town.

It was my understanding that beginning in 1988, the transmission mounts were changed so a VX transmission will likely not attach to your 86 civic frame.

I also believe that the VX transmission has a hydraulic clutch so you would need to find a slave cylinder/clutch pedal assembly.

I could be wrong on all of this- hopefully someone else can confirm/deny what I am saying.

Well, I would probably go for something that was an easy 'bolt on' that's why I thought of the first generation HF transmission. I would expect to see an mpg improvement though!