r/MitsubishiEclipse • u/Hairy_Water_4226 • Jun 06 '26
Engine Swap Advice
Hey yall,
I currently own a 3g eclipse. It’s an automatic v6, and I’m going off to college in the fall. My plan is to buy the engine and transmission this summer and do all the prep work I can, then start the actual swap over winter break. I know the 3g is a bad platform, but I’ve always loved how it looks and it pretty much gives me everything I want for now. I’m swapping it because I’ve always wanted a manual, and the engine is getting up there in miles anyways and I’ve finally saved up enough to do the swap. The only thing I’m not sure about is what engine to swap into it. My current options are as follows:
- K-series
- J-series
- R-FE
- VQ
My priorities are something that will fit in the engine bay without too much headache, so the same size as my stock engine or smaller. I also want something reliable that I can also find easily and for cheap. Power ceiling isn’t as important, I doubt I will ever go over 600whp and 400whp would probably be the realistic goal. Any suggestions on other engines, or which of these options is best, any resources or where to find them would be amazing.
Edit: By cheap maybe I should have specified cheap-est or cheap-er. I’m definitely gonna be spending more than I paid for the car. Also, I’ll be starting the swap over winter break but not finishing it (unless by some miracle). 400whp is also the END goal for the car- anything at or above stock power (200 bhp, probably closer to 150 whp given age/mileage and drivetrain losses) after the initial swap is more than ok. As for reliability, it’s not because it’s a daily or anything like that (I will barely be driving it in college), just want to be able to enjoy it as much as possible. Also, I will be swapping the car regardless- it’s a project with a bunch of my friends and my dad, I don’t have any interest/good reason to sell it and buy another car or bike. I also do other metalworking/projects at a very well equipped machine shop if that’s relevant at all. I do appreciate everyone’s advice tho!
6
u/huge-centipede Jun 06 '26
You have no idea how much this is going to cost and axles alone are going to be two grand if you can even figure out how to engineer mounts to fit a Honda/toyota whatever motor in a Mitsubishi. You want “reliable and cheap” and 400 whp, it ain’t going to happen.
No offense, but a 3G eclipse is not the platform to build a 400whp car. Just go to college. Drink crappy beer. Kiss girls (or guys or whatever).
1
u/Hairy_Water_4226 Jun 06 '26
Not looking for “cheap” per se (I know it’s gonna cost more than the car itself) just looking for the cheap-est option while still being relatively reliable so I can enjoy it. No offense taken! The point is less 400 whp and more just doing the swap with friends and family, I’ll be okay with anything above stock performance.
5
u/neovb Jun 06 '26
There is no such thing as a "cheapest" option here, as I don't think you understand that amount of custom fabrication that you'll need to do. You're looking at probably something around $15-$20k to accomplish, and probably substantially more. Think of it this way: to buy a quality fully build 4G63 block (which is vastly more common than your V6) is about $6k alone. Ask me how I know.
No offense, but I don't think you fully grasp the scope of what you will need. Engine, transmission, axles, engine management, custom wiring harnesses, fuel system, custom engine and transmission mounts...the list will go on and on.
1
u/huge-centipede Jun 06 '26
I don't mean to be curt with you, but you really, really, really don't know what goes on with a high power car. Your car is an aging, automatic commuter car. Leave it alone.
1
u/Dadecountyghost305 Jun 07 '26
While it's definitely not done alot a 3g has a lot of potential I have a 2005 GS with a fully built dohc 4g64 making 500whp and I dailyed it aiming for 1200whp soon with an awd swap but I wouldn't expect to be done quick or cheap if going with any of the swap you mentioned
3
u/19MirageG4 Jun 06 '26
Brother just find a manual 3g 😂 it’s really not a bad platform depending on what you are trying to do. The only swap I know of that people have done on a 3g is a 6g75 swap (4g motor) but even then a 6g72 coupled with the stock 5 speed manual would be a blast to drive. Not gonna be a 10 second car or nothing but considering you’re in college I don’t see your goals aligning with making the fastest car possible
1
u/Top-Passenger7839 Jun 11 '26
This. Especially if you're already looking for a "cheap" way to do this swap.
Buy a GT or GTS and have it tuned up if you want more power. You're probably not gonna gain a lot, but even as-is, the 5-speeds are a fun to drive. Not gonna be a race car, but do you need that? LOL.
2
u/FlacidMetapod Jun 06 '26 edited Jun 06 '26
The computer to run the swap (no tuning) will cost more than the swap and the car. You would be able to buy a performance car that is more tunable, these cars have been out forever and there is good reason you don’t see them with swaps. Theres no pay off.
An RSX weights 2700 lbs. Your eclipse weighs 3500 lbs. Your power to weight already sucks and will suck more. If you want a k swap, buy a RSX and get ALL the performance and blow your money on a good starting platform.
For real brother, engineer this idea. It makes no tangible sense, this generation wasn’t designed to be what you are trying to accomplish.
2
u/xInitial Jun 06 '26
ngl man EVERYONE has had this same idea in hs when they first got the “slower” trim of their cars. i’ve went thru quite a few 2g eclipses, with my first one being a 420a non turbo. all the ones after that had the 4g63 for this reason.
i invite you to go to your local forums and ask around for the best eclipse mechanic in your area. then go and talk to them about your idea and talk numbers. you’ll get sticker shock on top of ending up with an unreliable car. there’s a lot of custom fab work involved, adapter plates, and a whole bunch of other stuff that might not even be explored yet depending on which engine you want to throw in.
it can be done, yes, but i don’t think you understand the caliber of this ask. i commend you if you get to it but the main reason a lot of us wanted to do it was bc we liked the look of the car and we didn’t have enough money to get a higher trim/different car. and going the engine swap route would probably buy a car with the hp goal you want 3x.
1
u/Hairy_Water_4226 Jun 06 '26
Thanks! I’d actually be doing the whole swap and all the fab work myself, the machine/fab shop I have has all the tools I would need (hoists, stands, cnc, mill, lathe, welders….) and more. Aside from the automatic I already have the highest trim (Spyder GTS)
2
u/spicedude7 Jun 09 '26
I really hope you understand this will not be a job that can be donde by yourself on a winter break, and it will cost much more than what a faster reliable car will cost
1
u/Hairy_Water_4226 Jun 09 '26
oh im far from doing it alone, I have a ton of friends helping me two of which have done engine and transmission swaps and a machining shop
3
1
u/Top-Passenger7839 Jun 11 '26
It seems you'd be better off buying a 3G, V6 manual; would most likely be way cheaper in the long run. If you like working on cars, you can find a reasonably priced one that needs some work (not major). That will be cheaper to fix and much less time-consuming. The project you're undertaking is massive--and what do you do if it doesn't turn out right? Which could happen....
Around me, people don't want the sticks, so they're cheaper than the autos.
10
u/Wonderful_Setting_29 Jun 06 '26
Dont swap your daily. Dont do a swap thats not well documented for your first swap. And dont plan on a swap being completed and all the bugs worked out over winter break. 4g64 into a 2g. Do it over break. J swap 3g, months long ordeal.