Legacy GT vs. Outback ECU

[kookookachew]

After doing a little research I came across something of interest to me, that due to the speed rating of the OEM tires given to the various models of Subarus the Outback was given a 110 or thereabouts speed governor and the Legacy GT was not.

Now, before starting a debate about the legality/ what-for factor in this this was for research and there are plenty of people that will find this information interesting, as I did.

I decided to actually check this out for myself. I did, in-fact, discover the Outback's speed limiter, (in a safe area where the only person I could hurt was myself, none of the stupid street racing crap). I recently replaced the engine out of a '98 GT so I went back to the junk yard and picked up the ECM out of the same car and re-tested to find out that yes, its true, no limiter on the GT ECM.

Other notes, the Legacy GT ECM seems to run a bit differently, even more rich than the Outback's computer, and it seems to have more low-end torque (doesn't bog-down at 30 in 5th) and likes to pop out of the exhaust when getting off the gas after hard acceleration; old ECM did this but not as often. (UELs and straight pipe)

[mike-tracy]

Interesting... I'll have to try a GT ecu if we ever get one at the junkyard by me. Question: Was the ECU from the same year and a manual transmission like your Outback?
I used a 97 Outback ECU with a 98 Forester engine in my 96 Legacy, lol.

[anothernord]

I wonder if the GT's limiter is higher than the Outback's... If someone wants to sell me a GT ECU, I'll try it out with the help of a turbo. I can check to see if it runs richer too.

[kookookachew]

I pulled the computer from a '98 GT 5-speed, my Outback is a '99 5-speed, although my Outback is also running that GTs engine. Blew my head-gaskets and before I pulled the engine apart I thought I'd check the junkyard, they just brought in a mint black '98 GT wagon with a freshly rebuilt engine but a dented in drivers fender and blown clutch, from what I can tell, there was NOTHING else wrong. Picked the engine up for $150 with $25 core and picked up the rear wing for $20 and the ECU for $25 it also has mint GT seats for $30 a piece, getting those with my next paycheck :smt023

Also, from what I can tell from other Subaru forums, people in the mid-west (where they have the space) have had there GTs into the 130s, I managed 118 on my run, and I was almost out of steam. I need a tuneup on the new engine though, just did fuel injector cleaner today, seafoam tomorrow, plugs and wires soon, also need new air filter and new fuel filter

[kookookachew]

Nord, you're turbo'd now? What happened to your supercharger set-up?

[98outbackpdx]

After doing a little research I came across something of interest to me, that due to the speed rating of the OEM tires given to the various models of Subarus the Outback was given a 110 or thereabouts speed governor and the Legacy GT was not.)

115 for 99 SUS with original motor and 4 eat. also don't ask.

[DarkPhoenix]

I pulled the computer from a '98 GT 5-speed, my Outback is a '99 5-speed, although my Outback is also running that GTs engine. Blew my head-gaskets and before I pulled the engine apart I thought I'd check the junkyard, they just brought in a mint black '98 GT wagon with a freshly rebuilt engine but a dented in drivers fender and blown clutch, from what I can tell, there was NOTHING else wrong. Picked the engine up for $150 with $25 core and picked up the rear wing for $20 and the ECU for $25 it also has mint GT seats for $30 a piece, getting those with my next paycheck :smt023

Also, from what I can tell from other Subaru forums, people in the mid-west (where they have the space) have had there GTs into the 130s, I managed 118 on my run, and I was almost out of steam. I need a tuneup on the new engine though, just did fuel injector cleaner today, seafoam tomorrow, plugs and wires soon, also need new air filter and new fuel filter


Awesome find. The only reason you probably topped out at 118 is because the GT 5th is taller than the Outback 5th.

[kookookachew]

^^ Oh, I wasn't topped out yet, still had plenty to go, just didn't want to go any faster with the tires, (havent checked the pressure in a while) and they are only rated to 114, didn't want to spend good money on 15's when I'm hoping to pick up a set of WRX 17's

[ouch1011]

I ran out of power before hitting a speed limiter on my GT, but the ECM is out of a 98 2.5RS.

[kookookachew]

^^ By "ran out of power" how fast do you mean? Like, ran out of power before testing the 110 limiter or you just never found one and you were doing well over that?

[Dead91silvia]

I'll verify that a 98 GT BD can hit 120mph with an auto... Just dont recommend it... My car still had power, but the car was un-stable and started to float. Driving normal I can get up to24 mpg in the city, but my friend with his 98 auto OB can pull 27. We figure it's the ECU tuning...

Thats a screaming deal on a motor! Most yards sell them here for $800-1500 for a running N/A EJ25!

[kookookachew]

^^ Hmm thats weird, my OB was a little unstable, but not that bad, even at 118; and I have worn out stock struts, stock 205-70-15s, and a broken rear spring, I cant wait to pick up the rest of my suspension bits soon so I can actually feel that car handle properly again.

And I havnt noticed much of a difference in fuel economy at all, if anything its gone up slightly with the GT 2.5 and ECU, in my mixed loop I manage 22 and thats with some highway, some stop-and-go, and a fairly heavy foot. I imagine any gains are due to the fact that this engine seems to be more healthy than my old engine was, even before the head-gaskets blew.

And yes, I think its a great deal compared to buying an engine elsewhere, although most of the pull-it-yourself boneyards around here charge about the same. To manage this engine due to the rarity of a good 2.5, especially an apparently rebuilt one; I had to take a day off, and spend 4 hours in the pouring rain pulling it myself, it would have been soo much easier and quicker if the weather hadn't been soo terrible.

[ouch1011]

^^ By "ran out of power" how fast do you mean? Like, ran out of power before testing the 110 limiter or you just never found one and you were doing well over that?

It was about 115 indicated on the speedo, but because of my 3.9FD and the larger than stock diameter tires (about a 10% error on the speedo), that would put it in the 120-125 range.

Was done on a track, btw, in case any cops are reading :)

[Reason]

My 97GT stock with just a cone filter I buried the needle. Scary as hell the car felt like it was floating. My 98L cuts off at 100...

[89bk]

I wasn't sure if I should ask this in this thread or start another one, but here goes: Can I swap in a 5MT ecu into a Legacy with an AT? Are there any modifications needed?

[mike-tracy]

I wasn't sure if I should ask this in this thread or start another one, but here goes: Can I swap in a 5MT ecu into a Legacy with an AT? Are there any modifications needed?

The ecu for that generation legacy doesn't care whether the gearbox is auto or manual.

[89bk]

I wasn't sure if I should ask this in this thread or start another one, but here goes: Can I swap in a 5MT ecu into a Legacy with an AT? Are there any modifications needed?

The ecu for that generation legacy doesn't care whether the gearbox is auto or manual.

Great! Thanks for that info! :grin:

[Dead91silvia]

^^ Hmm thats weird, my OB was a little unstable, but not that bad, even at 118; and I have worn out stock struts, stock 205-70-15s, and a broken rear spring, I cant wait to pick up the rest of my suspension bits soon so I can actually feel that car handle properly again.

And I havnt noticed much of a difference in fuel economy at all, if anything its gone up slightly with the GT 2.5 and ECU, in my mixed loop I manage 22 and thats with some highway, some stop-and-go, and a fairly heavy foot. I imagine any gains are due to the fact that this engine seems to be more healthy than my old engine was, even before the head-gaskets blew.

And yes, I think its a great deal compared to buying an engine elsewhere, although most of the pull-it-yourself boneyards around here charge about the same. To manage this engine due to the rarity of a good 2.5, especially an apparently rebuilt one; I had to take a day off, and spend 4 hours in the pouring rain pulling it myself, it would have been soo much easier and quicker if the weather hadn't been soo terrible.

Yeah, after having my Silvia up to 140+mph, I can tell a little more with how a car feels. My 83 Celica would start to lose stability at 120-125, but it had suspension, wheels and good tires. I think the Supra spoiler helped also.

But I'm thinking with my BD, I do still have a bent frame rail from an accident about 4 years ago I havent fixed yet. I also have a set of H&R's and will be getting new struts soon as well. I'm sure I'll be stupid again and do another speed test. As soon as I get new tires for my BH, I'll see how fast that beast is with a 5 speed.

Funny little tid bit: If you swap an Auto ECU into a S13 240sx with a 5 speed, it eliminates the 120mph governor. I converted my last 93 240sx coupe from an Auto to a 5 speed and took her to 130ish... I know they cut out at 120 from my some of my other s13's I've had... So the same might be for Subies.... :grin:

[geckoboy86]

My 97GT stock with just a cone filter I buried the needle. Scary as hell the car felt like it was floating. My 98L cuts off at 100...


Thats odd...My 95L goes to 105 (did that today) on 205/55r16s.

What would be an upgrade (ECU wise) for my 95 L with a 2.2?

EDIT: Hit 112mph which is 180kph. Stupid ricer passing me and cutting me off in a no passing zone.

[slaytalera]

My outback is speed limited on the ECU to 110, it was still pulling strong as well. With the GT-B bumper there was almost no float, where as with the stock bumper it was very floaty.

[derrick_]

^^ Hmm thats weird, my OB was a little unstable, but not that bad, even at 118; and I have worn out stock struts, stock 205-70-15s, and a broken rear spring, I cant wait to pick up the rest of my suspension bits soon so I can actually feel that car handle properly again.

And I havnt noticed much of a difference in fuel economy at all, if anything its gone up slightly with the GT 2.5 and ECU, in my mixed loop I manage 22 and thats with some highway, some stop-and-go, and a fairly heavy foot. I imagine any gains are due to the fact that this engine seems to be more healthy than my old engine was, even before the head-gaskets blew.

And yes, I think its a great deal compared to buying an engine elsewhere, although most of the pull-it-yourself boneyards around here charge about the same. To manage this engine due to the rarity of a good 2.5, especially an apparently rebuilt one; I had to take a day off, and spend 4 hours in the pouring rain pulling it myself, it would have been soo much easier and quicker if the weather hadn't been soo terrible.

Yeah, after having my Silvia up to 140+mph, I can tell a little more with how a car feels. My 83 Celica would start to lose stability at 120-125, but it had suspension, wheels and good tires. I think the Supra spoiler helped also.

But I'm thinking with my BD, I do still have a bent frame rail from an accident about 4 years ago I havent fixed yet. I also have a set of H&R's and will be getting new struts soon as well. I'm sure I'll be stupid again and do another speed test. As soon as I get new tires for my BH, I'll see how fast that beast is with a 5 speed.

Funny little tid bit: If you swap an Auto ECU into a S13 240sx with a 5 speed, it eliminates the 120mph governor. I converted my last 93 240sx coupe from an Auto to a 5 speed and took her to 130ish... I know they cut out at 120 from my some of my other s13's I've had... So the same might be for Subies.... :grin:

140 is like a different world than 100 and under in a street car. 160, too, heh.