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Engine Swap Idea -- Let's Brainstorm

13073 Views 21 Replies 5 Participants Last post by  Thane
Disclaimer: This thread is intended to spark a discussion and could possibly evolve to an actual swap being attempted. Please avoid turning it into an insult-fest or pissing contest. People I'm hoping will join the thread have been through the common swap and have a lot of insight.

Background: I normally find the idea of engine swaps on vehicles built after 1995 to be a waste of resources (time, money, materials) because these later vehicles rely on computerized ignition systems, diagnostic, and emissions systems. I'm also turned off at the plain-Jane, ridiculous engine swaps most car guys do, which is to shoe horn a V8 (typically Chevy) into anything and everything, (IMHO) the dumbest of which is done to air-cooled Volkswagens. That being said, there are some swaps I can appreciate, one of which is the most common in the air-cooled VW world where the current common/popular swap is an older Subaru EJ series engine. One of the more clever I've seen is some series of Fiat engine that works well in an older Beetle. One of the rare V8 swaps that tend to work well is the First Gen Chevrolet Blazers. And then there is the popular 2.5L swap into the Mazda 2.0/2.3L that requires a minimum of parts to be changed.

The idea: I've been keeping a 2.5L swap in the back of my mind after reading several threads and communicating with those who've accomplished it. The process looks involved but isn't that scary (for myself). My vehicle's 2.3L has 164K miles on it and still runs well with minimal oil consumption, which I believe is due to my vigilance in maintenance. One item which I believe is overlooked is the valve cover gasket was redesigned to prevent excessive oil consumption. I caught that just in time during a routine spark plug replacement service when I observed oil soaked threads on #4 and minor soaked threads on #3 . Another indication of a problem was when I proceeded to remove the valve cover to replace the gasket -- several of the fasteners on the driver's side of the engine were loose. Since my vehicle is not in a rust belt state, I don't have the worries of corrosion that would normally preclude spending the money on a proposed swap.

Meanwhile, my mind will occasionally fiddle with the idea of engine candidates and what will be required for the swap. A few days ago, during my evening commute, I glanced over and noticed a Ford Escape in the adjacent lane. I remembered the Escape's engine is one of the more suitable candidates because, for whatever reason, they're cheaper to acquire. I noticed this particular vehicle had a V6 badge at which point my brain started wondering what it would take to put a V6 in my MZ3.

  • Will it fit in the Mazda's engine bay
  • PCM/ECU Requirements
  • Modifying the existing harness to work with the donor PCM/ECU
  • Transmission swap required?
  • Radiator upgrade needed?
  • Front suspension modifications required (extra weight of the engine)?
  • Front brake upgrades required? Again, extra weight of the engine)

If the engine won't fit in the Mazda's engine bay, then this idea is dead.

The donor vehicle's PCM/ECU will have to accompany the engine since the stock PCM is programmed for the stock 4-cylinder. That being said, will it be possible to modify the stock harness to work with the upgraded PCM? I'm thinking the donor's harness accompanies the engine as well as other connectors which feed the various dashboard gauges. That's where splicing and modifying harnesses will come into play and will entail referencing wiring diagrams for both vehicles.

Will the V6 engine bolt to the stock transmission, or will the donor transmission have to be adapted? If so, will the drive axles line up with the donor? That could be the show stopper unless everything is measured before the project is even attempted. Assuming the stock transmission will bolt to the V6, will it need to be strengthened to handle the extra torque? I don't know if the escape came with a manual transmission option, but my vehicle is an automatic. We can discuss both options.

The V6 requires more cooling capacity and may need a larger radiator if the donor's radiator will not fit the MZ3's bay. If the V6 radiator and I4 are similar, then that's money and time saved.

A large engine is going to carry a a few hundred pounds of extra weight, which is one aspect of a large engine most people don't take into consideration. That weight means the front suspension and brakes have to compensate for the heavier load.

Did I miss anything?

I'm just spit balling here since I've not seen any mention of this having been attempted. I'd love to be directed to any links if it has. I'm thinking a MZ3 with the V6 would be a major screamer as well as sleeper. Please daydream about this and throw out ideas.
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I think it would require a lot of money/time/modification to make it work. Having done the 2.5 swap in my '04, I think if I were to go for a sleeper, I would do the 2.5 with a turbo or nitrous slant and the necessary ECU tweaks to come out with a fast, cheap and relatively stock bang for your buck thing. The 2.5 in the older MZ3 runs pretty well with the stock ECU and exhaust. I can only imagine what it would be like to throw in the balance shaft delete, exhaust, turbo or nitrous and ECU tweak, CAI etc....

Although, I would love to see someone do what you are dreaming. Maybe you are the pioneer.
Like I said, I was just spit-balling mainly because the V6 engine started becoming a more viable option than V8s in terms of performance just after 2000. It seems a V6 conversion would take a lot more time and money than I'm willing to spend, so the 2.5L would be the better option. It's too bad a forced induction conversion is so pricey and that I'd be better off looking for a used Speed 3. I've considered doing so; however, I've outgrown the desire to drive a manual transmission after having done so for many years.

The mpg with a v6 would be really bad...I just drove a VW Atlas with a V6 and it ate through gas like twice as fast as my 3. It was fun to drive though...
FW Drive Monte Carlo with an LS engine. Possible of 650 hp or so...drool..

If you are going for power...might as well really go for it.
The fuel mileage aspect really hit me after I posted. I got around to researching the fuel consumption aspect (yesterday) and am curious if the V6 is more thirsty due to the weight of the larger donor vehicle and transmission gearing. I suspect that would be the case, which leads me to abandon this conversion. The fuel mileage drop is severe enough (to me) that the increase in power makes it an unwise trade.

My brother is in the shoehorn-a-V8-into-whatever camp. He thinks it's the perfect engine for any car, lol. He's done it and doesn't mind shortening drive shafts, repositioning motor mounts, etc.
Tell me about it. A friend of mine has a Ford 9N which he said, "I think it'd be fun to put a V8 in that thing." Apparently, there are conversion kits which make it possible, but some guys don't understand the difference between horsepower and torque. The V8 is great for the former and not the latter. Straight sixes are great at the latter and take time to develop the former.
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My daughter's Mazda head gasket went boom. That's why she now has a Ford Duratech engine in her Mazda3.

Plus, if someone is going to do an engine swap they can replace as many gaskets as they want before putting in the new engine.
I like that newer engines are using O-ring type gaskets everywhere that crush in lieu of the old style paper or crush gasket garbage.
I toyed with a Miata because they seem to be the most modified vehicle after the Volkswagen (air-cooled) Beetle and the Ford Model T. I'm thinking all of your research and information regarding an Eco-Boost swap is valuable and informative. Issues I see are the ones you've noted, mainly being the engine mounts and exhaust. Since that engine is typically installed in an engine bay of comparable dimensions, I don't see it being an issue in a MZ3; however, the PCM and TCM could present potential issues.
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