'93 Civic Si hatch D16Z6 engine w/ VX transmission?
 

Hi all,

New member here. I've been a hypermiler for almost 20 years and couldn't believe when I found this website that there are actually others with a healthy obsession/compulsion w/ good fuel economy.

I recently sold my 225,000 mile '95 Civic VX to buy down the mileage, but can't find a relatively low mileage/good body '92 - '95 CX or VX replacement for it...I want to continue with a high mpg car (maybe I sold too soon). I've expanded my search to include the DX and Si. I recently found a '93 Si hatchback and wanted to find out if it's possible to install a VX transmission into the Si w/ its original D16Z6 engine. I figure with the lower revving VX tranny, I should be able to squeeze 40 - 45 highway mpg from it.

I already asked one member in a private message if this tranny swap is s straight swap without having to change axles or anything else, and he said it should be an easy plug and play. But I wanted to throw it out there for feedback from other members before taking the plunge and buying the Si.

Also, any idea if the 13" VX rims will fit the '93 Si hatch? The Si seller says no, brakes are too big, which is why Honda used a 14" wheel. Any idea? Thanks for all feedback.

Yeah, it's a straight swap. I'd just go swap the engine too, but it's easier to actually find a VX. The CX is more common, so you may try looking for that.

VX rims won't fit, the brakes are too big. HX rims will though.

I say go for a cx/vx from the start.

with the tranny swap alone 40mpg is possible if everything is running the right way and you drive on the conservative side.

but yes the tranny is a straight swap as said by SVOboy and you may use the axles from either. you could also very easily sell the si transmission for $100 in a week. however the whole swap will sell for a lot more and is a lot easier. is the vx that tired?

also, yes the vx rims will not fit, nor will any 13in wheel.

EDIT: btw, ben your fuel economy has gotten great! 5spd + mid ftw!!

Thanks for both of your responses.

Aren't there other issues w/ doing an entire swap, such as relays, wiring, etc.? Why is an entire swap easier? Sounds like the Si w/ just a VX tranny swap is not the way to go, especially since I won't have the option of superlight wheels and tires I was planning on w/ the VX wheels. The Si is tempting b/c the interior is mint and exterior is close to mint; no rust, no major dents. But I think I'll be patient and wait for the right CX or VX to buy unless someone talks me into this VX engine and tranny swap (if it's really that easy). I can get a VX tranny and engine w/ 73k miles on it from a wrecked car.

My VX wasn't that tired. Just too many major maintenance items coming up in the next year (oil leak: oil pan gasket and/or rear main seal and/or crank seal; rust was starting to get bad on passenger side quarter; needed new tires; EGR ports needed cleaning; etc.). I had never replaced the axles, so I figured those were due also. Original clutch and tranny as well. I figured selling it now and putting the $ towards a $3500 - $4000 CX or VX w/ 100k - 130k miles and better body was a better option.

I haven't driven an SI yet, so I can't say for sure, but I suspect that the power band of the SI engine is not going to match to the gearing of the VX tranny, as it looks like you have almost no engine tourqe at all untill about 2,100rpm or 2,200rpm (from a chart in the civic factory shop manual) and I know from experince that my VX tranny hardly ever lets the engine rev above 1,800rpm, and at that engine speed, I think the SI engine is going to run extreamly poorly.

Do you mind if I ask how much you sold your VX for? I bought mine with 204,000 miles, some body damage, the start of some rust, a bad o2 sensor, worn out suspention pivits, so I replaced all of those things, and a few others (new shocks and springs), I might have spent another $1,500 on all of those parts in total, but it feels like a brand new car now, has 235,000 miles on it at this point, and as long as it doesn't slide on an icy road in to a light pole, it should last another 200,000 miles.

with the whole swap i am pretty sure the only major issue would be going from the 4 wire o2 sensor to the 5 wire.

on second thought, the tranny swap would probably be just as much work as the full swap. i couldnt couldnt ever imagine driving a d16z6 with a vx tranny. its ok with the dx/lx tranny but the cx/vx would just be murder.

Ryland, I sold my VX for $2250. It had an oil leak (I think a combination of crank seal and oil pan gasket), needed 4 new tires, had the usual rust above rear wheels (not bad fo # of miles and age of car). Clutch, axles, distributor (some common things I've seen replaced on other VXs w/ fewer miles) were all original. Engine burned no oil and clutch still felt strong when I sold it. I sold because I decided to buy down my miles, figuring a major repair expense would come in the next year.

By the way, I decided against buying an Si and swapping the tranny.

i think thats a good move. so what are you looking for now? i would try to find a civic hx. i think i want to get one...

I bought a '95 Civic DX hatchback w/ 68,000 original miles, all stock. Only driven 1.5 tanks so far. First tank, 38.3 mpg....vey disappointing. All highway except 5 miles of crawling stop and go traffic in Washington DC on my way back from NC where I bought the car; about 70 - 75 mph, some drafting behind trucks and buses. Tires are definitely not LRR. I'll see how the next tankful is, but my plan is to swap the tranny for a VX or HF tranny. If I can't get MPG to 45+, I'll be very unhappy.

38 isnt bad for going 70-75 thats actually ok. i wouldnt worry about getting an engine swap. and you cannot put an hf tranny into an eg. the dx motor will do just fine for now, you will get more efficiencies through aerodynamics and lrr tires. the transmission will make more of a difference than the motor btw.