Transmission interchangability

[MotorsportsMatt]

Hello All,

New to the forums here and wanted to start off by saying howdy! :D

Also have a question about the Legacy GT 2.5 turbo transmissions and was hoping someone could help me out. I've been considering doing a 2.5 turbo engine and automatic tranny swap into a impreza RS for some time and recently heard that the legacy Gt's have pretty much the same motor with slight differences and a much "higher performance" automatic transmission.

Does anyone know if this transmission will bolt right up to the wrx 2.5 turbo engine, or is the legacy GT's tranny hardwired pretty much to the stock computer? Any help will be greatly appreciated

Matt

[Dookie]

Welcome to the forum Matt!

Engine swap from LGT to WRX, hmmmmm.....I haven't heard of that one, but I'm sure it's very doable. Several members have done the STI to LGT swaps and made them work, so it's def possible. Some of the members here will chime in and point you in the right direction.

[havanisda]

I have a 5EAT and I don't know if its more high performance than a 4EAT. I know I can shift on the sterring wheel and I'm pretty sure the 4EATs can't. I wouldn't consider it high performance, its more of a novelty since its the slowest way 2 change gears. Manual shifting on the floor is a little faster and fully auto is the fastest.

[urabus]

ha, me shifting with a manuel is fastest

[havanisda]

ha, me shifting with a manuel is fastest I doubt it, no1 can shift faster than a computer. By the time u push the clutch and grab 4 the stick the auto is already climbing in the next gear. BTW who's Manuel? :lol:

[han]

Haha "Manuel"

I agree that the auto can shift faster.

As for the swap, Aren't the newer LGT auto transmission's ecu like cointerwagulated with one another or something? Like, It has to have the trans ecu, and the main body ecu, and the engine ecu, or it wont work?

I am pretty sure the older, previous generations' was possible to swap one auto trans to another vehicle pretty easily, but with the newer cars, I think it might be more of a pain for what it is worth. Unless you swap all the wiring harness from the LGT to the RS.

But I dont know anything about swaps, so, TSi+WRX!!! where are you!

[MotorsportsMatt]

Engine swap from LGT to WRX, hmmmmm.....I haven't heard of that one, but I'm sure it's very doable. Several members have done the STI to LGT swaps and made them work, so it's def possible. Some of the members here will chime in and point you in the right direction.


An STI to an LGT swap? Thats very interesting. Is that for an earlier model STI or is it for people who really likes the 2.5 more than the 2.0 engine?

Oh I mistyped in the last sentence in my original thread, meant a legacy GT engine/tranny or just legacy GT tranny/wrx 2.5 engine into RS impreza swap. Sorry for the confusion :o

[havanisda]

An STI to an LGT swap? Thats very interesting. Is that for an earlier model STI or is it for people who really likes the 2.5 more than the 2.0 engine?

Oh I mistyped in the last sentence in my original thread, meant a legacy GT engine/tranny or just legacy GT tranny/wrx 2.5 engine into RS impreza swap. Sorry for the confusion :o

All the USDM 05+ Legacys are 2.5 and thats what the majority of the people on here have.

[MotorsportsMatt]

Yep totally aware of which engines came in the year 2000+ cars, the way it was previously worded "STI to LGT swap" makes it sound as if people were going from an STI to an LGT or dropping an LGT into an STI chassis, and not the other way around. Usually when I hear people refer to a swap you hear the engine getting swapped out first. IE 302 to 351 swap. It did sound silly, but I'm relatively new to subarus and had never heard it put the other way around. I logically assumed that maybe some non-US cars were maybe doing the swap for the additional .5 displacement starting point possibly for some combination where an additional .5 displacement was needed.

Its clear now what was means was an StI swap into and LGT chassis.

[urabus]

if auto is faster, how come drag times for manuals are faster. You cant power shift in an auto. How come drag cars are manual?

[TSi+WRX]

MM - My apologies for not having offered a proper welcome. :o :)

Also, my further apologies in not being able to help you much in this case. This is simply well beyond the shallow pool of my technical know-how as a backyard shade-tree greasmonkey wrench. :o

However, I hope I can offer you a little more insight:

Indeed, the "STi-swap" is a popular one for us 2.5GT owners. Grabbing the larger turbo and TMIC (and sometimes even the intake manifold) from the STi can net us significant gains, particularly once other hardware is addressed and the tune finalized.

However, you'll note that this isn't a true "engine-for-engine swap" in the more conventional sense of things.... It's merely the transplant of a few key components to an otherwise cross-compatible powerplant, and an ECU readjustment to get everything sorted-out.

What you're proposing, just from a first gut-instinct kind of review, is, I think, much more complicated than that. I would imagine that aside from mechanical concerns, there would indeed be some electronic/computer trickery that must be accomplished - plus perhaps even hardwiring.

Honestly, I just don't know....and sadly lack sufficient technical knowledge to either tell you outright that this will be "next to impossible" or, alternatively, "easy as cake." :o

Try the same question over at .com , or even take it to Nabisco. I do not mean to suggest that our brothers here are any less technically proficient, but for one thing, I'd see if the just the larger population sampling over there can help you make more headway on this issue.

Best of luck! :)

[MotorsportsMatt]

Excellent, totally respect the honesty. "Moves hand away from ninja monkey summoning button" :cool:

I've been talking to a few local subaru guys who say the Legacy GT is a bit more complicated. They say the factory computer comtrols more than in the WRX and STI. Heres the point where my knowledge on the subject is lacking.

One would think the LGT 2007's stability control system would be linked into all this. I can't however imagine on the 2005-2006's there would be too many headaches when swapping in the engine AND transmission in a complete package. I mean hell, It seems like in that case you're pretty much taking most of the car at that point anyway.

Matt M

[TSi+WRX]

Excellent, totally respect the honesty. "Moves hand away from ninja monkey summoning button" :cool:

:lol::lol:

Where did you get that button? I need one! :lol:


One would think the LGT 2007's stability control system would be linked into all this. I can't however imagine on the 2005-2006's there would be too many headaches when swapping in the engine AND transmission in a complete package. I mean hell, It seems like in that case you're pretty much taking most of the car at that point anyway.


Good point on both counts.

If both parts are moved, and the ECU and accessory electronics made the move, too, that would be essentially like just putting a different body on the same car....

It just sounds too easy.....:confused: