96 Civic CX Hatch Swap Ideas
 

First off, I hope I won’t make this another thread that goes nowhere.

I had a 97 Civic EX/Si that I loved so much and fixed up only to have it get crashed into back in March. Was only a week after I fixed the engine, so I ended up buying a 96 hatchback to transfer all my work over to. Sure enough, it’s been sitting around in my yard. It is in good enough condition with little rust but the riced out engine inside it is toast. I’m looking at my options for new engines, with my plan A being the freshly-fixed D16Y8 (stock) from my old car.

I like the get-up-and-go of the D16Y8. I was getting 30-38 MPG after correcting my testing methods. However, I recently bought a 2008 Civic LX with an R18A1 engine, and that is crazy in comparison. Pulls great, and it seems to get the same or better gas mileage! Makes me inspired to try and put a newer engine into my old car. I don’t mind the cost of the swap and I find the job very interesting.

My goal is to have the same or hopefully better gas mileage than I am getting, with more power. Reliability is key as well, but Honda is Honda so I am not too worried. Here’s a list of what I was looking at, lemme know what you think:

D16Y8: I have this on hand. 30-38 MPG in my ‘97 Civic EX/Si; 127 HP; 107 lb/ft; 1.6 litre.

B16A2: I also have this on hand. 25-30 MPG (?) in a ‘99 Civic Si; 160 HP; 111 lb/ft; 1.6 litre.

R18A1: Im looking for one. 30-45 MPG in a 2006-10 Civic (according to my research); 140 HP; 128 lb/ft; 1.8 litre.

K20A4: I’m looking at a 2006 Accord with one of these. I’ve seen them do 25-35 MPG; 160 HP; 166 lb/ft; 2.0 litre (?)

K20Z3: There’s an Acura RSX near me with this. 20-30 MPG; 155 HP; 138 lb/ft; 2.0 litre.


Interested in any thoughts/ideas/recommendations. I’ve always a 45-50 MPG hot hatch, and that’s why I’m looking for opinions. The K20A4 and R18A1 are the most interesting to me.

Obviously a D-series would be the easy option. And they can be really efficient. I was getting 70-80 MPG in my old Civic Wagon with the D15B2. But you mentioned power, which I didn't have! What about a newer turbo L15? Good for 35 MPG combined in the newer Civic. And about 180 HP.

I’ll read up on the L15, seems interesting! It’s likely out of my price/availability range as it’s in the newer vehicles, so I’d have to scan salvage auctions or something. The list I posted is based on what is possible near me.

Agreed on the D series. It’s my main route I’m planning to take if none of these engines materialize. I’d convert my Y8 to a Y5.

The R18A1 seems really promising. I’m working on my ‘08 coupe and the engine seems simple and reliable. Supposedly it is an Atkinson cycle engine with a three-stage VTEC-e style system. I find the coupe pulls really well and is more than fast enough with the stock 5 speed. There’s only three mounts and I believe the axles are compatible with the EG/EK hubs. The hard part comes with the electronic throttle and dual dashboard gauge clusters. I love those things but they’d look out of place and would likely take a lot of wiring magic.

Hence is why an Accord engine seems cool. In a 3000lb chassis I’m seeing people get upwards of 35 MPG, and it has analog gauges as well as a mechanical throttle setup. That seems the most promising, and Accords seem more commonplace as well.

So yeah, R18A1 seems awesome but has a lot of wiring. K24/K20 seems easier but likely less MPG potential. I’d bet it could do better than my D16Y8 average though.

I had a K24A2 in my Insight. With custom gearing I could get within spitting distance of 60mpg on the highway. Mind you that's already a slippery car, but the difference between 25mpg and 60mpg is really more in the gearing and less in the engine.

My money is on the L series. They're lighter than D's, and a dime a dozen because they're dead reliable and nobody knows what to do with them, so junkyards are full of healthy L engines. The L15B1 in the 3rd gen Fit makes the same horsepower as the D16Y8. My ex's 5MT Fit would regularly return near 50mpg even with its terribly short gearing. They're definitely more efficient than a K series, and you have more in the way of options and variety than with an R engine.

The 10th gen Civic's L series engine produces around 180hp and has been reported to deliver 60+ mpg if driven carefully.

The advantage of the K series is that there is a ton of aftermarket parts that make any K series engine drop-in for your chassis. You wouldn't be inventing any of it.

Hm, maybe I will look into those.

I found an ‘07 coupe with the R18 and an auto trans for $1200. I think I’ll try that. Good parts car for my ‘06 if I change my mind with the engine. The custom fab isn’t impossible but I can see how it would be tricky.


Edit: Scratch that. Manual swapping those engines is a pain.

I might just play it safe and stick to what I have. Turbos seem neat though! I’ll keep my eyes peeled for any local scrapper cars, and update accordingly.

IIRC, the R and L series engines rotate the opposite way from the D series--and have the transmission on the opposite side of the engine bay! That means the mechanical part of the swap is more involved with them, versus the D or B swaps. (Not sure about the K series.)

I like KISS--D-series to D-series is the most straightforward swap, plus you already know you like what you have. If you're interested in better freeway MPG, you may be able to find a taller 5th gear for your transmission.

K series spins the same way as R and L. And, I agree with this logic, it's certainly easier and more cost effective.

The D16Y5 and D15Z1 both have a roller rocker valvetrain and lean burn, which is good for a fir bit of extra economy.

A 5th gear swap is not terribly complicated either, and is likely going to have a bigger impact on highway economy than changing engines.

These are both good bits of advice, although I’ll add that I never did break 50 MPG consistently in my 97 coupe. Meanwhile I’ve broken it pretty easily in my 06 coupe with the R18A1. More power than the D16Y8 while closer in economy figures to the D16Y5. And this car is much heavier as well. I do have the freshly-fixed Y8 from my car that got destroyed in a hit and run, so that’s the backup plan of course.


I’ve managed to get a hold of a certain Hondaswap guru, who is the only one to have done this swap to my knowledge:

https://youtu.be/U6r22wCzuzw

He said it was complicated but not impossible. The engine mounts were the trickiest part. He bought a 2006 coupe as his parts car and sold what was left to recuperate the $1000 he spent. I asked him about fuel economy and he told me the car gets 32 MPG in the city and 48 MPG on the highway. That’s pretty awesome for a non-hypermiler with no aero mods. The biggest fear I have is electrical wiring but he told me he used almost everything off the parts car without many issues.

I’m gonna keep browsing around for a donor car. Even if I don’t do the swap, I still want the newer seats and interior parts for my hatch. 90’s seats come stock with cigarette burns and mold around here.




As for taller 5th gear swaps, I’m divided on that one. There was a guy on Honda-tech with a Del Sol VTEC that would get 50-60 MPG and he went very into the reasonings why a taller 5th wouldn’t help. I forget the forum post but he definitely knew his stuff. I know this CX hatch has a ghetto-spec D16Y8 with a Y7 trans and the powerband is messed right up as a result. Terrible on gas, terrible to drive.

In steady-state driving, there's a direct relationship between gearing and economy, up to the point the car can no longer maintain speed in top gear because it's so tall. There are very few exceptions to this. If you have shorter gearing, you're going to need to use pulse and glide to reach maximum economy. If you're using p&g, taller gearing will provide much less benefit.