Not to take anything away from Soletek (because I think his setup sounds fantastic), but wasn't there a guy on this board who had a 2nd gen CRX HF (88-91) with the Civic VX engine & HF trans? I still remember pictures of it with the front of the car sitting an extra 1-2 inches higher due to the supposed weight difference with the (lighter?) VX engine. Was I hallucinating? Where did that car go? I was dying to hear the final curb weight of it, as well as how much more MPG it would get. If anyone knows who that car belonged to, please drop a name. I hate when these projects just disappear.

Upon your request I went over my notes and did a little research on gear ratios and did find that the '88 to '91 CRX HF had two different final drive ratio sets: 2.95:1 federal and 3.25:1 CA. The '85 CRX HF tranny that I took out had a final drive ration of 3.25:1 which is the same ratio as the '92 to '95 CX-VX. The information stated that the '88 to '91 CRX HF had 3.25 first, 1.65 second, 1.033 third, .823 fourth and .694 fifth. The '92 to '95 CX-VX had the same first gear ratio 3.25, second is 1.761, third is 1.066, fourth is .853 and fifth is .702. As the ratios are so close and with the added torque and horsepower that will come from the VX over the HF, if I feel, in the end that I can use taller gears, I will just change to larger diameter tires and because the car weighs so much less than the VX it probably won't bog down while starting off. I chose the CX tranny over the HF because it allowed me to use the vehicle speed sensor and all connections that come on the VX platform. This car is going to be driven on the street so I want to be able to trust my speedometer. My HF tranny had a cable driven speedo and no check engine light in the cluster.
As I do with all of my cars, this one will get some track time and the CX tranny is a heavier duty unit than the '85 HF.

I'm sure you will notice a difference there. I currently have lightweight Nokian tires on my car (supposed to be FE friendly), running 50psi., mounted on the superlight Mazda Miata BBS wheels...a very light combination. However, I did actually notice a LOSS in MPG when I swapped to this setup from my previous set of heavier 13 inch Mitsubishi Mirage rims with big fat 185/80-13 no-name overinflated tires. Yes, those big, ugly, bulky tires still helped me net a +3MPG effective increase. Which reminds me -to those of you who go with a larger overall diameter, remember, you have to figure an 'effective' MPG, since your speedometer will be inaccurate.

Not to overwhelm, but I am something of a math nut. Just figured out that the 165/75/13 that came on the VX as original stock, had a calculated diameter of 22.74409 inches. Multiplying that number by the final drive ratio of the federal version of the HF which equals 1.026 taller gears than the VX, equals a tire diameter of 23.33544, subtracting this diameter from the previous equals a difference of .59135, so taking it a step further, the calculated diameter of a 175/75/13 (the tires that are now on the car)equaled 23.3346. taller than the original VX tire by .59055 almost exactly the same final drive ratio as the HF. Now my head's tired -- I'm going to bed.

wasnt there a 1983 crx hf? i'd would think that would be the lightest. i'd rather have a crx :p

In the US the first year of the CRX was 1984, and in 1984 they didn't have an HF in the US insted they had a 1.3L engine EPA was high 50's low 60's, but then in 1985 the EPA changed how they mesure gas mileage and that year honda came out with the HF modle, either way the 1.3L engine was higher reving and put out nearly the same power as it's slightly larger but lower reving 1.5L HF engine.
Of course this is just US modles, if you lived in Japan or a few other countries you could get a CRX in 1983.

@ Soletek: what did you do with the HF engine? Hope that can be put to a good use as well.

I actually have my eye on a pretty nice 1986 Civic hatchback Si and if I am not mistaken putting the HF engine and tranny in there should be 'plug and play' right?

i wonder what kind of gas mileage that 1.3l would get now, if you could find one.

https://www.motorbase.com/shop/profiles/by-id/241/
Includes, Si, 1.5, 1.6, Coup, Spyder. 100 pages, 200 illus, SB. a spyder crx?!

McPatrick, I still have the HF engine/tranny. Why I pulled it was because the head gasket had blown and it was burning 1 qt oil per 1000 miles. When I got the car it had 320,000 miles on it. I wanted to get a realworld baseline on what that HF engine would do for fuel comparison purposes against the VX, so I had the head rebuilt and they didn't even replace the valves when they replaced the valve guides so I bought brand new valves and replaced them myself. I also replaced the bearings on the crank and rods. The engine got a best average of 51.7 mpg. Once the headgasket blew I decided to go ahead and switch to the VX since that was the reason for purchasing the car in the first place. As for plug and play I don't have a complete answer, but the HF CA version (at least this CA version) has a 3 bbl carb and I was under the impression that the Si was fuel injected. Please correct me if I am wrong.
I have been contemplating the idea of rebuilding the HF engine in its entirety for resale purpose and/or selling it as is or for parts. No decision yet.

Honestly, people, this is too coincidental:

Ebay item: 1.3L CRX HF '84...see for yourselves
Item #250220047445

Link: (copy & paste) https://cgi.ebay.com/ebaymotors/Honda...QQcmdZViewItem