1998 Civic LX to HX D16y5 conversion has begun!
 

I have given up looking for a CLEAN HX in this area. They're either completely trashed and asking way too much or are clean but asking way too much.

I decided to just get a complete D16Y5 and swap it into my LX. That way I can keep my A/C and cruise control.

I have gotten a best of 37mpg in the D16y7 and would say I average ~35 which isn't bad considering I do zero hypermiling at all.

I didn't get the longer geared y5 transmission. I am going to stick with my y7 ratio'd trans and see how it goes.

I will be installing this 100% complete and will even make the *useless* upshift light work.

Here's the motor / harness / ecu I picked up today and believe it or not the exhaust manifold has NO crack!!!! Hooray!

T-belt, valve cover gasket, oil pan gasket, rear main seal, cam seal, front crank seal will all be installed before dropping this engine in.

I plan on having it up and running by next weekend.

I'll report the change in MPG *if any* on this thread so people in the future can decide if this swap is worth it.

My calculations say that if fuel is $3 a gallon and I gain 6mpg by doing this then the conversion *Total of $650 including all new parts being installed* will pay it self off in 56k miles.

Bear in mind, I am into the LX ~$1500 dollars so by spending another $650 i'll be into it $2150 and there's NO way to find anything still resembling a HX around here for close to that price.

The other side to this is the Y7 will get Vitara's and rods and a full refresh while out. I'm going to be building it for boost along with a chipped p28 ecu and will use that in a year or two for some fun racing at the track so the Y7 being removed won't goto waste.

I am also doing this to go back to obdii *currently running chipped p28 ecu* because I do have emissions testing in the next few months.

I also miss the ability to use scangauge, ultragauge etc with obdii.

I have an mpguino ordered and am just waiting for it to get here.

I also already have a Uego wideband on the car and am going to be installing one of those economy vacuum gauges when installing the engine.

I will not be doing any extreme hypermiling but instead will just drive as smart as possible, when possible and see where that goes.

I'll also make sure all fuel ups are calculated via corrected odometer + actual gallons to fill and keep it updated for accurate logs.

Lastly, if I don't see improvements that satisfy me I will source a VX transaxle and see how much of a difference that makes.

Some may say I'll never see a ROI doing this stuff but to me I am a tinkerer and enjoy doing stuff like this, besides, I'm certain I could re-sell the y5 and or vx transmission and recoup some costs down the road if I get tired of it.

Welp, thanks for listening and if anyone has any feedback, shoot away!

Don't get a Taller trans, I'm sure you will be happy with the LX trans, as I believe it's 3.73. 6mpg would probably be on the low end, that's only a 30% increase. If you have appropriate tires and keep your speed at 70mph or lower, 50 should be possible. At least 45. If you want, you can go the Taller geared trans from the VX/CX and lower your tire size to P165/65R14 Bridgestone potentza Re92's. Then you will definitely get 50mpg easily.

[Edit]: Your car will probably look silly with such small tires, but you are driving this for mileage and gas savings, no?

Thanks for the input. Right now with my y7/y8 mini me I'm running the ex trans that's geared with the 4.25FD. From what I understand my LX trans has the 4.058 FD but I have not confirmed this.

I do plan on just using the LX transmission for 10 or so tanks and see where that puts me.

I think my next modification will be to lower the car a bit, it sits silly high on stock suspension.

I gathered my FD ratio from this site:

Honda Transmission Calculator by ZealAutowerks

In for results! good plan and something I'd do if I had the time and the car. Alas, I don't want to buy a car and immediately swap it out, so I'll just check craigslist for cheap blown up civics and see if there's an option for this, just encase. Then back to the HX search lol.

HX has the 3.73

I thought the LX/HX had 3.73 and the EX had 4.10? The CX/VX have 3.23 though. With RE92'S it's about 2600rpm at 70mph.

If you gonna need tires sometime soon, either get Re92's, or if you wanna stay the stock tire size (185/65R14 right?) get Michelin energy savers. I don't know what you are running right now, but tires make a huge impact on mpg.

The hx and lx have the same gearing. It's not worth the effort to upgrade as the hx can only enter lean burn at a certain speed. The lower geared trans would mean less time in lean burn.

Good luck with your project