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Question for 2.3 to 2.5 engine swap guys. 2.5 vs 2.3 acceleration.

5K views 10 replies 5 participants last post by  ultimica06 
#1 · (Edited)
Does your car feel dramatically quicker accelerating now with the 2.5 vs your 2.3,or just kinda more...torquey?

I know the 2.3 likes to rev more.

Just took my stock 2004 Focus zx3 2.3 manual out for a spin and boy-when I get the revs up a bit...it seems like it pulls harder than the 2.5 swapped mazda3.

Granted it does weigh a couple hundred lbs. less than the 3 as well.

It's been a while since we had our old 2.3 2005 Mazda3, and it was an auto,and I've never driven a manual 2.3 mazda3-so that's why I ask.

The 2.5. swapped 2005 Mazda3 that's sitting in my driveway(technically not mine just yet) has a 2011 fusion motor swapped in by P.O.

Its otherwise stock running a bsd,the 2.3 injectors,stock mazda3 ecu,stock mazda3 inlet manifold with(non-port matched as far as I know)manifold adaptor plate,and the stock 2.3 intake cam.

It feels quick to me at first,because with the 2.5 torque and good gearing, first gear is almost too good as far as gearing,and 2nd isnt too far off.
Getting traction with the new el cheapo tires that the PO put on is terrible,even in the dry.

Driving old man style- the car sure gets up too speed so much more effortlessly than the focus,as while the focus mtx-75 gear ratios arent dramatically different than the mazda trans,the FD ratio sure is.

For 2 years ,03 and 04,ford decided to put a 3.42 FD ratio in the focus cars with 2.3. While it works great with an fswerks turbo kit,as you can imagine,it's terrible for accelerating naturally aspirated.
Mazda actually put a good ratio final drive ratio in the 3.

Anyway,even maintaining traction,the Mazda 2.5 car just doesnt feel fast.

Granted I was pulling away from my son in our manual trans 2015 2.5skyactive mazda6 car we have,but that 6 also weighs 3232 lbs....

I think maybe the 3 needs a tune.

That mis matched intake and adaptor bugs me too.

Not sure if i would port that out though.

If the manifold is coming off then I think a proper 2.5 manifold of some sort will be going on.

But I still have to deal with California smogging though.....

Anyway,I try to short shift the 3,thinking it's a torker-not a revver vs the focus..which I will wind out a bit.

Perhaps the son and I will do some acceleration tests and compare the cars.

Just wanted some input from others out there who have driven gen 1 manual trans 2.3 cars and have swapped to the 2.5 in the same car.

Also,if anyone is tuned...how do you like it and who did your tuning?

.
 
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#4 ·
I'm completing a swap now. I do feel like it is a bit quicker. One, it's 15 more horses and around 10 more lbs of torque. Also, mine is a MT, so I feel like it pulls pretty well.

However, I have the 2.5 injectors in. It does still have the 2.3 tune. Not sure if that's much of a difference. A proper tune will help you and I greatly.
 
#5 ·
Thanks for the answers guys. I have the manual trans as well.

I'm going to plan for a 2.5 intake manifold and 2.5 injector swap along with a tune.

Have NO IDEA who can tune this Naturally aspirated 2005 Mazda3 though.

I read the threads and it's either old info/tuners or I find bad stuff about the tuner.

I'm going to start another thread on available tuners for Gen 1 Mazda 3 NA cars in the year 2020.

.
 
#6 ·
I believe the 2.5 intake will work, but with quite a bit of work (I've been looking into it a little, haven't done a whole lot of research). I went with the 2.3 intake due to the following observations and the intake runners that the 2.3 has.
My observations:
1. The throttle body has a different bolt pattern so to use the 2.5 manifold, the 2.5 TB will have to be used or an adapter plate made to fit the original on the 2.5 manifold. It doesn't have the small coolant line going through it like the original (not sure if necessary). The elect connection seems to be the same, but it doesn't mean the wire positions are the same, so it may not be sending proper signals to the correct terminals. A test will have to be done to see if it will operate correctly.
2. The EGR and vacuum connections are a little different. I can't say it won't work, but the connections may be different so they won't fit together.
3. The original has intake runners that are controlled via vacuum and the ECU. If using the 2.5 manifold, the ECU will no longer see the runner selonoids, so it will throw codes. So it needs to be fooled to believe they're there, or a ECU flash needs to delete them.
 
#7 ·
I'm in the same boat for tuners. I haven't looked real hard yet, but all the info I've seen is outdated. There's a couple shops around me that I might look into. I will be very interested in what you come up with though!
 
#9 ·
Unfortunately, this site seems to have lost interest in the first gen Mz3. Only thing they seem to care about anymore is newer Speed3's. I've posted a few questions and had a no-start issue I needed help diagnosing. No replies, at all.
 
#10 ·
There probably isn't a lot of reply because the first gens are "old" now. There's some of us still here.

I didn't know a 2.5 engine swap was a thing. Maybe if the engine went on mine, I could throw a 2.5L in instead and then turbocharge that? Is there a guide out there people are following for this?
 
#11 ·
I've got a 2009 1st Gen 2.3 Engine w/ AutoMagic! I have around 150k miles on it.

So all I have done was upgrade the RMM to the solid rubber EFocus one & a solid rubber PMM and regular Tranny Mount....I also have an Intake and Exhuast...Thats it.

For some reason I have a lot of Torque when going off the line at a stand still....and its a peppy ass engine...Never had any issue with it nor the Transmission.

So maybe I just lucked out?...**Knocks on Cyber-Wood**...
 
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