turbo build info

[Garrison]

There are a lot of informative posts here that are looking out for your best interests.

"What do you want?", is the most important of them, imo.
If I had my way, I too would do RS25, with a sti swap (that, or build the engine with sti pistons, crank, and rods. Then slap a VF, or turbo of your flavor on it and tune from there.

Just lock down what is important to you first, and then let us know. I guarantee someone on here will have the knowledge/expertise to help you along the way.

Budget ~ $2000 for your build (not saying you have to spend that much, but have it there on hand if you don't feel like shopping for the best deal) and you'll drive away happy.

[Garrison]

So I'm goin to drive one of the autos while i plan on taking the 5mt motor and sinking a lil money into it so it's turbo ready. New pistons. Crank. Rods. Bearings. Etc

New clutch. Install. Get it driving. Sell both auto leggys. Take that cash and buy my turbo n intercooler n zaust set up

No wiring nightmare. No crazy fabrication. Close to "stock" as possible with a built motor and turbo

I'm confused, did you purchase a 5mt transmission? (5mt engine is a misnomer, as any subaru can swap between auto and x-mt transmissions). My point is, if you have the coin and want to build and engine, then do so. But do it correctly the first time. Do your research and understand that the stock 5 speed won't hold more than 8-10psi on the stock clutch. Upgrade the clutch and now you're wearing out the other driveline components and something will eventually fail.

Turbo builds don't have to be ludicrously expensive, but they do require time, energy, and a lot of research to do properly.

Here are a couple of links that I would recommend you read religiously before you make your decisions.
Hope the info helps!

https://sl-i.net/FORUM/viewtopic.php?f=39&t=22065
http://www.rs25.com/forums/f7/t139473-b ... guide.html

[jewbaru]

I am buying a third leggy today. That is a 5mt. And it's more cost effective for me to tear that engine down n rebuild it. Are you a fan of the RS because it's dohc or.... And yes. I'm going to upgrade the clutch. How can i make the 5mt handle 15-18lbs?

[jewbaru]

Sunroof's add 100lbs easy.

Noooooo way. I can't see that

[Garrison]

I am buying a third leggy today. That is a 5mt. And it's more cost effective for me to tear that engine down n rebuild it. Are you a fan of the RS because it's dohc or.... And yes. I'm going to upgrade the clutch. How can i make the 5mt handle 15-18lbs?

I'm a fan of the RS because of the looks of the vehicle, no other reason. The engine/tranny are identical to what you're purchasing. (assuming a 2.5L, pre-2000 legacy)

Sounds like you've got a good donor platform. But when you're talking tranny's you need to measure things in terms of torque. Hp is a factor of torque, so when you say 15-18lbs of boost, that doesn't really mean anything. Now, that being said, a stage 2-3 clutch from Exeddy, or ACT will suite you well if you're not hammering on it (4 wheel burnouts, drag launches, etc).
Reinforcing a trans is not a cheap endeavor, you're looking for cut gears, reinforced splines and gear dogs. PPG gears are a good choice too but then you're looking at $2000-3500 for that setup alone. Basically, the stock tranny wasn't made to handle those numbers and the old adage of "a chain is only as strong as its weakest link" holds very true for these things. Something -will- break. There really isn't much in terms of a (n inexpensive) way around that fact.

Huffer is right, the sunroof has a large motor which pushes/pulls it, not to mention the thickness of the glass. Compare that to a piece of sheet steel covered by paint on one side and headliner on the other... you do the math, but I assure you it's a good bit. That being said 100lbs = ~7hp.

[mshriver]

I am buying a third leggy today. That is a 5mt. And it's more cost effective for me to tear that engine down n rebuild it. Are you a fan of the RS because it's dohc or.... And yes. I'm going to upgrade the clutch. How can i make the 5mt handle 15-18lbs?

Time Out.... Are you planning on putting a turbo on a N/A 2.5L engine and expecting 15 lbs of boost?????? No, you can do about 5 -8 lbs before blowing the poor thing to kingdome come.

Why dont you pull the engine out of your new car and sell it or keep it for a spare or something other than slapping a turbo on it? Then sell one of your auto legacys. Use the money from one of those to buy a wrecked wrx / sti / 05+ LGT / FXT, etc. Then swap legacy number 3 the right way. Theres really no point trying to work with that NA number to save money because it just isnt going to last and will need a custom tune.

If I were in your situation I would post whichever auto leggy I didnt want to keep on nasioc for trade for a wrecked sti/ wrx. Some unfortunate person who has nothing to drive because they wrecked their car should jump all over that.

[jewbaru]

I am buying a third leggy today. That is a 5mt. And it's more cost effective for me to tear that engine down n rebuild it. Are you a fan of the RS because it's dohc or.... And yes. I'm going to upgrade the clutch. How can i make the 5mt handle 15-18lbs?

Time Out.... Are you planning on putting a turbo on a N/A 2.5L engine and expecting 15 lbs of boost?????? No, you can do about 5 -8 lbs before blowing the poor thing to kingdome come.

Why dont you pull the engine out of your new car and sell it or keep it for a spare or something other than slapping a turbo on it? Then sell one of your auto legacys. Use the money from one of those to buy a wrecked wrx / sti / 05+ LGT / FXT, etc. Then swap legacy number 3 the right way. Theres really no point trying to work with that NA number to save money because it just isnt going to last and will need a custom tune.

If I were in your situation I would post whichever auto leggy I didnt want to keep on nasioc for trade for a wrecked sti/ wrx. Some unfortunate person who has nothing to drive because they wrecked their car should jump all over that.

well, after finding this 5mt leggy for 2Gs

i was planning on taking the rest of my insurance check (roughly 4gs) and rebuilding the engine completely from the ground up because i can still drive one of the autos around while im building the 5spd

also, on the note of selling one of the other two, the lemon, car number two, is getting a good majority of the parts from car number one and two (minus wood grain and black seats cuz thats going into number 3) but me and a friend are doing some body work and paint on number two to make it look all purdddy then were flippin it and the money from that car is going towards my new paint and some body work and to pay him for the effort hes putting in.

sooooo that being said

interior from number one is going into number three
interior from number three is going into two
tranny and misc parts from one are going into two

car number two will be a nice little piece when shes done and make me and my friend a nice little amount of cash

car number one is basically getting gutted for everything shes got to make number two and three look nice

but are you guys saying that with a rebuilt engine, my block still isnt going to be able to handle a turbo?

and i might like the idea of getting a blown engine or something and rebuilding it so i have a spare..

goddamn all these options haha

and i think swapping in a WRX set up is going to b a bit outta my pricerange/time range/effort range/knowledge range

you cant use just the block from an auto engine to build a manual engine can you?

[Garrison]

but are you guys saying that with a rebuilt engine, my block still isnt going to be able to handle a turbo?

and i might like the idea of getting a blown engine or something and rebuilding it so i have a spare..

you cant use just the block from an auto engine to build a manual engine can you?

No-one is saying that. If they are, they haven't read the Xmillion threads on nasioc/rs25 about people doing it. What I, and from what I gather mshriver, are saying is that you can't run what you're looking for in terms of boost through the oem driveline without something breaking. 12psi is enough to incenerate your rear differential, 8psi is enough to roast your clutch if you drive carelessly.

Spare blocks are great. Pick up something worth having.

Yes. Again, any subaru pre-2008 will mate up to any pre-2008 subaru transmission with enough work.

EDIT: By the way, when you say "rebuild" the engine, let's get on the same page. I'm talking sti pistons, rods, and crank. That will require a machine shop to regrind the block to accept the crank.

This thread should clear up some questions you'll have:
https://sl-i.net/FORUM/viewtopic.php?f=11&t=22430


EDIT: I misspoke above. mshriver was in fact saying that. His reasoning is as follows:

all na turbo setups people do can run like max 5 psi stock, 8-10 psi with different pistons. That wont make nearly the power you could with a turbo motor. Plus the cost of the parts you are going to put into building the motor + the needed aftermarket engine management to run your custom setup will end up costing you just as much as if you did it right and went with a 2.0 or 2.5 turbo swap.

[redlegacygt]

your best bet like everyone else had said is to either get a wrx or sti wrecked car. Not only do you have that power, but every part you will need, plus some. And also the ability to produce more power with all the aftermarket stuff available for those cars... By turboing your 2.5, your shoehorning yourself into an expensive corner... you'll get ok power, but be very limited and less reliable..

[jewbaru]

Yes. Again, any subaru pre-2008 will mate up to any pre-2008 subaru transmission with enough work.

EDIT: By the way, when you say "rebuild" the engine, let's get on the same page. I'm talking sti pistons, rods, and crank. That will require a machine shop to regrind the block to accept the crank.

This thread should clear up some questions you'll have:
viewtopic.php?f=11&t=22430

by "enough work" you mean the blocks dont match like "stock" right?. At this point i am basically looking to be able to bolt in a motor without crazy extra work like wiring etc. i want it to be plug and play which is why i think doing up a NA block that bolts and plugs right up is a good idea, i wanna try to pick up a 2.5 motor from a 5spd and build that up with the STi internals etc. if down the road it blows or has any issues, ill have the stock back up that can swap in for down time

as mentioned above, the trannys are the same from the RS and my car? is it just the diffs that are different or.. what makes the leggy drive train so weak compared to the impreza?


and i do plan on putting a nice clutch in there just to add that note

[jewbaru]

your best bet like everyone else had said is to either get a wrx or sti wrecked car. Not only do you have that power, but every part you will need, plus some. And also the ability to produce more power with all the aftermarket stuff available for those cars... By turboing your 2.5, your shoehorning yourself into an expensive corner... you'll get ok power, but be very limited and less reliable..

the WRX motor will still require changing my harness etc over.. thats another expensive corner i kind of dont want to get into because it isnt something i know the first thing about if i ever have an issue..

i might have to sacrifice running 15+psi and stay lower around 10, just to give me enough edge


edit: i am very farmiliar with the 2.5 blocks and i believe if built right the motor will be fine.

is it possible to swap over diffs etc and keep my engine and tranny setup and build up the driveline without a wiring or fabrication nightmare?

[redlegacygt]

you can get your harness merged for about 600 now a days and all you'd have to do is put them in a box, wait a week, and then install back the way it was.. If you turbo build, your still going to do wiring because you'd need to run some sort of engine management to protect the built motor. Those can be just as much of a headache and cost more then having your harness merged. Sure you could run something like a PP6, but a Greddy Ultimate or a Links G4 is prob. are alittle more money, plus you'd still have to wire them in yourself...

In any build or swap you do, there's going to be stuff that you aren't familiar with or that your uncomfortable with, but thats when you need to look at your options in those situations to figure out which is more realistic for you budget.

[mshriver]

but are you guys saying that with a rebuilt engine, my block still isnt going to be able to handle a turbo?

YES..... you could go through putting in forged pistons and blah blah but you are still not going to be able to run hardly any boost. its not worth it

and i think swapping in a WRX set up is going to b a bit outta my pricerange/time range/effort range/knowledge range

No.... rebuilding the stock one for boost is going to be far more expensive than a swap in the long run

[Huffer]

The normally aspirated shortblock for an EJ25 is an open-deck block. The WRX and STi are sem-open/semi-closed decks. The venerable block in the EJ22 turbo'd early legacies are closed-deck.

Put it this way - a turbo engine is less likely to punch a hole in a cylinder wall if it detonates in an extreme fashion.

However, if you sleeve the cylinder and use the appropriate pistons, you can still run plenty of boost - as long as your tune is correct.

[Garrison]

The normally aspirated shortblock for an EJ25 is an open-deck block. The WRX and STi are sem-open/semi-closed decks. The venerable block in the EJ22 turbo'd early legacies are closed-deck.

Put it this way - a turbo engine is less likely to punch a hole in a cylinder wall if it detonates in an extreme fashion.

However, if you sleeve the cylinder and use the appropriate pistons, you can still run plenty of boost - as long as your tune is correct.

Huffer hit the nail on the head. Controlling detonation (i.e. controlling heat) is what counts. Fuel quality, quantity, and intercooling/cold plugs (charge temp reduction) are your best friends.

[jewbaru]

way to much information running through my head lmao. I need to make this a daily driver, so ive even began looking into a turbo baja set up, they run the same engine correct?

[httrdd]

Change the thread title to "turbo build info." Seems like you are way off the Wrx ej20 swap.

[anothernord]

The whole open-deck vs closed-deck debate has recently come to and end as people have found that that aspect only comes into play at much higher power levels. Under 400 HP or so, the rotating assembly, as well as the pistions and rods are the weak point.

A homebuilt turbo setup CAN give you WRX power levels for less than half of the price of a swap. The catch is that you have to spend time tweaking things to get it to work perfectly.

The WRX 5MT and the N/A 5MT are largely the same as far as strength, with the exception of a few WRX boxes, which had wider gears. There are plenty of people, myself included, that run more than 200WHP on a N/A 5MT. The people who say that it can't handle turbo power are saying so because they did a 6K clutch dump and shredded a gear. It's all about how you drive it. All components have a failure point, and with an AWD car, you can't be putting tons of shock load on the gears like that.

You can run more than 10 PSI on a stock engine, but you can not do so without good engine management, fueling, and intercooling.

[jewbaru]

Change the thread title to "turbo build info." Seems like you are way off the Wrx ej20 swap.

thanks

[jewbaru]

The whole open-deck vs closed-deck debate has recently come to and end as people have found that that aspect only comes into play at much higher power levels. Under 400 HP or so, the rotating assembly, as well as the pistions and rods are the weak point.

A homebuilt turbo setup CAN give you WRX power levels for less than half of the price of a swap. The catch is that you have to spend time tweaking things to get it to work perfectly.

The WRX 5MT and the N/A 5MT are largely the same as far as strength, with the exception of a few WRX boxes, which had wider gears. There are plenty of people, myself included, that run more than 200WHP on a N/A 5MT. The people who say that it can't handle turbo power are saying so because they did a 6K clutch dump and shredded a gear. It's all about how you drive it. All components have a failure point, and with an AWD car, you can't be putting tons of shock load on the gears like that.

You can run more than 10 PSI on a stock engine, but you can not do so without good engine management, fueling, and intercooling.

smart man

[lord flashheart]

Im confused. Do you currently not have a car?

Buying a new legacy and turboing a NA engine is an even worse idea then trying to do a wrx swap without knowing what your doing. My 2 cents is buy a wrx or even look for an 05+ GT. Ive seen them in the 6-7k range.

If you want to swap / turbo a car that did not come that way here is a good way to do it.
1. Buy either a swap or complete parts car
2. Do whatever you want to the engine and have it all pretty and on a stand ready to go in the car before you touch your car.
3. Buy a legacy wiring harness for the same year and model as yours.
4. Send the swap harness and your legacy clone harness to iwire, ecs, etc.
5. Have everything ready to go in the car.
6. Then bust everything out in one weekend..... No downtime

^this.

OP, swaps take more than a wink and a smile, they are alot of work, lots of time and money. but if your up to the task it can be very rewarding. and i would urge u to buy a wrecked car and swap it over. it will make it easier. information is going to be your biggest ally. i would make sure you have wiring diagrams, and a shop that does swaps number on speed dial. also feel free to PM me if u have any questions. i have a bit of experience in this area.