90s Legacy Twin Turbo Engine Swap

I was browsing on ebay and I came across a bunch of JDM twin turbo legacy engines, many with transmissions and ECUs, for around $1500-$2000. Many of them have really low mileage, despite being 15-20 years old. I did some research and supposedly these twin turbo engines of this era make pretty good power (250-280 crank).

 

If basically everything I need to make good turbo power is in one of these packages for the right price, why wouldn't anyone do this? Has anyone heard of this swap being done? The way I see it, I bet it would be a really economical engine swap.

 

Don't bother commenting if you're gonna say something like "Sell your car and get a GT." There were many other reasons why I got a 2.5i at the time, so don't piss me off with that type of comment.

Why hasn't anyone done it? Because the twin turbo setup does not fit in a LHD car. The brake booster/MC, clutch MC, and steering shaft all get in the way.

 

If you want to make more power in your 2.5i, I suggest saving up some money.

So no GT? Lol

Do more research. A lot of people ditch the whole sequential turbo setup and go single. Why? Horrible torque drop between the first turbo running out of puff and the second one taking over. Like, barely-driveable kind of horrible. As BAC5.2 mentioned, the twin-turbo crap doesn't fit with LHD anyway.

As a guy who had twins and went to a single, I would say the dip was not "undrivable" it was just inconvenient. Having a single turbo makes the subaru a better daily drive, I think, because I didn't have to deal with the touchy torque in first. A little turbo lag is a good thing.

I was browsing on ebay and I came across a bunch of JDM twin turbo legacy engines, many with transmissions and ECUs, for around $1500-$2000. Many of them have really low mileage, despite being 15-20 years old. I did some research and supposedly these twin turbo engines of this era make pretty good power (250-280 crank).

 

If basically everything I need to make good turbo power is in one of these packages for the right price, why wouldn't anyone do this? Has anyone heard of this swap being done? The way I see it, I bet it would be a really economical engine swap.

 

Don't bother commenting if you're gonna say something like "Sell your car and get a GT." There were many other reasons why I got a 2.5i at the time, so don't piss me off with that type of comment.

 

Those TT setups aren't optimal the boost handling between the two turbos results in a flat spot in the mid RPM range. Not to mention you will have to stuff that TT in around your brake booster, steering column,slave cylinder and your engine cradle. Then the harness merge.

 

 

HOwever for $2000 and all what you get, one could get a low mileage EJ, convert to a single turbo (VF46), swap that in and have a pretty decent swap. If you have the space/tools/patience/spare $$$ it could be a worthwhile investment!

Those TT setups aren't optimal the boost handling between the two turbos results in a flat spot in the mid RPM range.

I got to drive a few of the TT B4 models in Australia and experienced the torque trough in all it's horror. Where did you get your seat time? I wouldn't have thought these RHD-only models would be too common in the US...

I got to drive a few of the TT B4 models in Australia and experienced the torque trough in all it's horror. Where did you get your seat time? I wouldn't have thought these RHD-only models would be too common in the US...

 

As fate would have it I too saw the allure of cheap TT setups on the various online retailers(about 7 years ago). However, after a few 100 PM's, video requests and user impressions I decided NOT to pull the trigger.

As fate would have it I too saw the allure of cheap TT setups on the various online retailers(about 7 years ago). However, after a few 100 PM's, video requests and user impressions I decided NOT to pull the trigger.

 

Ah. So you didn't actually drive one then. Nevermind. Carry on.

I got to drive a few of the TT B4 models in Australia and experienced the torque trough in all it's horror. Where did you get your seat time? I wouldn't have thought these RHD-only models would be too common in the US...

 

I've driven an imported RHD wagon with the twin turbo.

 

They don't call it the "valley of death" for nothing.

I've driven an imported RHD wagon with the twin turbo.

 

They don't call it the "valley of death" for nothing.

 

Yeah that is what I gathered from the owner remarks (UK and New Z) that I talked to when contemplating the purchase. Otherwise a stout setup and something I would still consider as a BE project!

 

Ah. So you didn't actually drive one then. Nevermind. Carry on.

 

You can't help but be an azzhole, asshole.

You can't help but be an azzhole, asshole.

 

You can't help but regurgitate stuff you read on the Internet and present it as your own experience, and I couldn't help but expose you. If that makes me an asshole, I'm okay with that.

Good info in the thread that answers the OP's question. Let's keep it on topic. Thanks!

Why the hell did Subaru mass produce these things?

 

Even if I was enamored with have a TT car and didn't care about the performance, it would be pretty damn embarassing take someone for a ride into the "valley of death."

 

Can you imagin pulling out to pass a car and all realize the torque drops off for a couple of seconds...

 

Is it that bad ?

The one I drove in Japan was just like that. Attempted to merge on the Daisan Keihin (Japan National Highway 466 - equivalent to our typical freeways). Romped on the gas, all good, went to upshift and merge and it just lagged like crazy to the point that I thought, holy crap, what just happened? Pulled back out of traffic.

Why the hell did Subaru mass produce these things?

 

Even if I was enamored with have a TT car and didn't care about the performance, it would be pretty damn embarassing take someone for a ride into the "valley of death."

 

The mass-produced them in Japan, where a majority of owners didn't spend much time past 3400 rpm - making a small turbo that spooled up very quick a good match for the street conditions there.

 

Avg. speed through Tokyo according to my GPS - 15km/h. Over several years of driving. I owned three of those cars, and am the originator of the VOD term from my tenure on the NASIOC forums dating back when it wasn't NASIOC.

 

The flip side of that was, if you did like to wring it out on the track or twisties, the car made good power if you were shifting at redline. It would keep you right above the VOD then. Keep in mind, the twin turbo legacies were 2.0-liters, and were first made when the 2nd gen Legacy body showed up in the early-ish 90's.

 

In 2003, a Subaru engineer risked being sent to a remote dealership on the tip of Hokkaido by creating and presenting a single twinscroll as an alternative to the twin's. A lot of people didn't like that idea.

So that sole engineer pitch a twin scroll single turbine design that made Subaru ditch the parallel turbo idea? That is neat and it is also cool hearing about members that have lived through the Subaru evolution to this point in time. I bet when that TT was announced forums and such (if they existed) went nuts. So this VOD is the action of smaller turbo running out of breath and the larger one coming into boost? SO shifting at redline would mean shifting at the peak of the small turbo and the stat of the larger turbo powerband?

 

What did you think about driving them hard ? This is an out there question but did you ever run two BOV's ? IF so when shifting would they vent in sequence (small then large) ?

 

 

Sorry just a Subaru era I missed out on

VOD was a combination of a couple of factors, I think. One was the complicated valving necessary to switch on the secondary - the other was that filling said piping had a tendency to vent all the boost. Generally, at about 3200-3400, suddenly the turbo's had to re-spool. Which took about 600-800rpm to get it fully up to boost again.

 

If you were shifting at redline, you basically would land at about the spot where the secondary was finally going strong, so it wasn't that bad.

 

And if anybody drove them hard, I did. I ran the TT Legacies at Twin Ring Motegi more than a few times. The biggest issue there was braking, not power...

The one I drove in Japan was just like that. Attempted to merge on the Daisan Keihin (Japan National Highway 466 - equivalent to our typical freeways). Romped on the gas, all good, went to upshift and merge and it just lagged like crazy to the point that I thought, holy crap, what just happened? Pulled back out of traffic.

 

Describes my own experience to a tee. You cannot appreciate the reality of that torque hole unless you've actually had a car cut out on you or lose half it's cylinders with a semi about to crush you if you don't move NOW. The graphs and 2nd-hand chatter just don't do it justice.

 

You can learn to drive around it in normal use but it's a pain in the ass. I'd much rather have a later boost threshold to deal with and reliable torque from there up than this on again off again horror.

 

Funnily enough I spotted the part below today at a buddy's shop. This will remind anyone who's actually seen one of the true horror of complexity the TT setup brings. This shows the diaphragm valve that closes off one intercooler feed pipe so the charge doesn't recirculate from one turbo into the other. Just one more thing that will fail at the split of a vacuum hose...