Gen 2.5 3.8 Swap

ChargerX3

Observer
Nicely done!

Am i right in ASSuming that the minimum effort way of doing this in my Gen2.5 would be to just dump in a non-MIVEC 6g75, and then bribe one of you guys to flash my ecu with some conservative maps, then spend some time with some det cans to make sure it's not knocking? Or would the 3000GT SL ecu be a PNP affair?

You are assuming quite a bit. Motor mounts will need some work and possible welding. Accessories will need some modifications. Likely quite a few other odds and ends pertinent to your montero. You could plug in the SL ecu but the other problem you have is that you wiring harness lacks the proper shielded wire going to the knock sensor. Would have to wire that in. Other than that a 98-99 montero or montero sport would be the best donor vehicle for a MIVEC swap.
 

Swank Force One

Adventurer
I have a 98 Montero (gen2.5). Motor mounts shouldnt need modification. The aussies have the mechanical side of the 3.8 swap ironed out pretty well.

I'm not real interested in running a Mivec motor on a window switch.

So the SL ecu and a couple wires gives me working knock to go with a late 3.8 sounds easy enough. Then just have to find someone to flash the ecu? Thanks!
 

ChargerX3

Observer
I feel you are underestimating the complexity of this swap. Also not all configurations of the 6g75 are the same. That includes motor mounts and their bosses.
 

Swank Force One

Adventurer
I feel you are underestimating the complexity of this swap. Also not all configurations of the 6g75 are the same. That includes motor mounts and their bosses.

I feel like i'm missing something... are you saying that Mitsubishi took the time to make entirely different blocks for different cars that were all called 6g75s? Every single thread i've been able to find concerning a 6g74 --> 6g75 swap says "use your gen2.5 motor mounts, they bolt to 6g75," which is the only reason this swap is interesting to me. I've done a motor swap or few in my time, the electronics were previously the only thing that worried me about this, since typically i just go straight to a standalone, but i'm not interested in doing that in this truck.

If the mechanical stuff isn't actually straightforward, then there's really no point in sticking with the Mitsubishi family at all for me. What am i missing? There's been dozens of 6g75s swapped in Gen2.5 Monteros, but there's been some concern about running them on the stock unflashed ecu, which is why i was following this thread. If the ease of this swap mechanically speaking that's been communicated is incorrect, could you please elaborate?
 

ChargerX3

Observer
Yes I have seen variances in the blocks. Heck there are quite a few configurations for the 74 alone depending on what year and on how it's mounted in the engine bay. Best to do your research ahead of time.

It can be done and easier that other builds out there but you will have to research it out.
 

Swank Force One

Adventurer
That's what i'm trying to do. Every thread but this one says grab any old 6g75. Most threads have concerns about running the motor properly.

This thread is the only one that does anything about it, there is nothing else out there in my hours of searching that addresses running the new motor "properly," which is why i'm asking the questions i am in here. :)

There's far more information about V6 swapping a 93 Ford Escort than there is about this should-be-easy swap.
 

ChargerX3

Observer
Sadly I don't have all the 6g75's in front of me or at my disposal, so I can't solve your dilemma. It will work but you will need to research your specific application. It sounds like you have done motor mounts before so you should be up to the challenge. I had to weld a boss onto my passenger side block to get it to work. Yours may be different. The divers side I had to weld iron onto the mount to make it sufficient to support my anticipated load. Again if you are confident with welding, and cutting a little then you should be ok.

If going 75 go MIVEC. Just about as easy to find as the non and your gains are much more. You will regret putting in all that work just to find yourself wanting more.
 

Swank Force One

Adventurer
Sadly I don't have all the 6g75's in front of me or at my disposal, so I can't solve your dilemma. It will work but you will need to research your specific application. It sounds like you have done motor mounts before so you should be up to the challenge. I had to weld a boss onto my passenger side block to get it to work. Yours may be different. The divers side I had to weld iron onto the mount to make it sufficient to support my anticipated load. Again if you are confident with welding, and cutting a little then you should be ok.

If going 75 go MIVEC. Just about as easy to find as the non and your gains are much more. You will regret putting in all that work just to find yourself wanting more.

I'd love a MIVEC, but the electrical side of things i'm not real excited about. Is your window switch just set up as on/off at certain RPM and then you manipulated the fuel/timing maps in the 3000GT ECU to compensate for MIVEC behaving in a manner that it doesn't in OEM form?
 

ChargerX3

Observer
If you ease into 4K rpm you can feel it. Otherwise it just feels like the engine likes to gobble up the rpm from idle to the top. It's not overly crazy. Then again I have a long manifold runner so I know that is killing top end.
 

Atrais

Adventurer
If you ease into 4K rpm you can feel it. Otherwise it just feels like the engine likes to gobble up the rpm from idle to the top. It's not overly crazy. Then again I have a long manifold runner so I know that is killing top end.

But dat torque tho...
 

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