[Pontius DIO]

First off, this was a first time rebuild and upgrade, and I scoured videos, online tutorials, etc. and was left scratching my head as much of what I saw was either incomplete or just outright wrong (even reputable links had mistakes). Every diagram I came across was for multiple models. So something might go on an actual T28xx turbo and not a T25; some stuff is for the older carbon seal models. So, I took a diagram and drastically revamped it so it can actually be clearly understood, as well as omitting useless drawings from the diagram and relocating others to reflect their actual relationship to the rebuild and reduce clutter. I also renumbered everything and made a separate checklist as an image. Big thanks goes to "JIM" at "Gpop Shop" for spending some minutes telling me what's what ;ol; It should also be noted this is for OUR NG900/9-3's with a T25. Other cars might be different!

Here's the Diagram:

Checklist with clarifications in the notes:

 

[Pontius DIO]

Now, if you have a T25 and would like to upgrade it, you are in luck because there are some options! On my T25 I only upgraded the compressor wheel, and left the exhaust wheel alone. The compressor wheel used is what's on GT2860RS turbos. This essentially turns it into a T28 with a small exhaust wheel. If you do a full conversion meaning installing the exhaust wheel as well, it's typically referred to as a "Big" T28. In order to get the compressor wheel to work, you need to machine the CHRA so the wheel can sit in the recess. You also need to have your stock compressor housing's A/R size ported out to accept the new wheel, or buy a GT2860RS compressor housing suited to the wheel you buy. For the "Big" conversion, you need to get a larger exhaust wheel/shaft (they are welded together so they come as one) and have the exhaust housing ported out to accept that wheel as well. I also STRONGLY suggest you port your exhaust housing's runner as it's a choke point, as well as upgrading to a 360 degree rebuild kit to make this practical. YOU MUST get a balance when you switch out wheels. And YOU MUST clean the exhaust wheel off (to BARE metal) in case it has stress cracks like my factory exhaust wheel had @168k miles. I did everything in house except the balance. If you aren't comfortable widening the hole in the CHRA for the new wheel, take it to a machine shop and have them put it on a lathe. Take the factory wheel too so they will know how much clearance to add between the wheel and opening by going off the clearances for the factory wheel. Here's my disclaimer: Do this at your own risk. If you mess up, it's your fault. NEVER force anything. If the exhaust wheel and shaft won't go back in easily, DOUBLE CHECK your work! If you get in a pinch and need help, contact a reputable turbo shop. You can PM me here at Saab Central if you need clarification or help. I'm no pro, but I feel comfortable with this turbo and I might be able to answer a question or point you in right direction. GET A PROPER BALANCE OR YOU'LL RUIN IT!

This was after the balance. Two of the C-Clips are in the housing already. The nut, thrust washer and collar are still on the shaft as they're needed for the balance.

Both compressor wheels side by side. Which one would you want?

GT2860RS wheel mocked up. I traced it's diameter to prepare for the Dremel.

Look closely and you'll see the tracing around the stock wheel.

Tape the opening off. I carefully went around in a circle as shown. I used the old center to gauge how deep I was. Big thing is that the wheel NEVER touches anything. Shadowing makes it look wider. *I strongly suggest a machine shop*

I hit the surface with a wire wheel in a drill. Finished will look like so:

 

[Pontius DIO]

If you follow the diagram, everything should go together OK assuming your shaft isn't bent, or the piston ring is funky. I used clean motor oil on every part that went back in.

Here's the original exhaust wheel and shaft. Look VERY close and you'll see the cracks. They were COMPLETELY hidden before it was cleaned. When the factory piston ring went, the back of the wheel hit the heat shield, causing these cracks as well as digging grooves into the wheel's back. Had this gone unnoticed, a BIG BOOM would ended a day in no time.

Here's some marks left from the balance to align it properly:

This is a groove people mistakenly stick "extra" parts into, most noticeably a coil washer people get in their rebuild kits. DON'T DO THAT. If your's is coked with oil, clean it!

This is a "stepped gap ring". It's just like those "gapless" rings used in engines. I paid extra for it, but it seated better than the normal cheap one in the kit. It can handle your abuse better :cheesy:

This is the groove it goes into. Take your time and carefully work it over the 1st groove and into this one:

 

[Pontius DIO]

I didn't bother cleaning the outside of the center housing. But I did use a fine mill file to clean the openings for the oil and coolant banjo bolts. I stuck some paper towel bits in the holes to keep the filings out. If you look carefully at the hooked pick's tip, it's pointing to the old copper ring's seating position. If this wasn't cleaned, the high spots from the rust around it could cause leaks with new copper rings and possibly broken bolts from over tightening to try and "stop" the leak.

Just knock the rust off for a flat mating surface. Make sure to keep it even and don't over do it!

Here's the CHRA assembled. It SHOULD SPIN FREELY! If there's any binding, DOUBLE CHECK YOUR WORK! If it's really tough to turn and you are POSITIVE the piston ring is seated correctly in the center housing's channel and no mistakes are on your end, DOUBLE CHECK that the shaft is NOT bent! It's possible to bend them with a hammer if you hit it wrong. Sometimes a little force is needed to seat the exhaust shaft's piston ring. If you used oil on the ring, it should snap in place with little effort.

When the turbo originally went, I pulled the center housing out and plugged all the lines off. I left the exhaust housing attached and made a simple block-off plate so the car would be drivable until all this was done. It was a blessing in a way as I discovered that the exhaust housing itself is EXTREMELY RESTRICTIVE. It's the T25's Achilles Heel. On some T25's from the 9000, you can port the opening oval like the gasket; using the gasket for a template, and port the header outlet to match as well. I covered this in another post, but on this housing, that's not possible as you'd grind a hole through the pipe or the flange. But you can widen the runner and go into the hole and remove some restrictions.

Look carefully at the T25 flange (turbo's inlet side with studs), see where it gets thin near the center of the flange? This is why you can't go oval ;ol;

Before porting:

After porting:

Don't mess with the A/R (the area in front that encompasses the exhaust wheel). I hit the area in the back near the carpet. It's explained in the link below.

This minor porting helped the car TREMENDOUSLY with it's NA (naturally aspirated form) performance. 0-60 was 4-5 seconds faster, and I was able to climb a steep hill nearby with about 15 more MPH by the time I hit it's crest. The run before porting was 30 MPH and the car just held 30MPH to the crest. After porting it was at 45+. How the turbo even gets past this in stock form is a puzzle to me. I'm actually going to port a little more before everything is back in as I think I can get more performance out of it. Anyways, if you're going to "upgrade" your T25, I STRONGLY suggest porting this like in the pics especially if you start going over 15psi of boost. You should get better spool, better breathing, and lower EGT's. Well worth the 45 minutes of work. Stock T25's can surely benefit as well. Here's the original porting link with video links in it:
http://www.saabcentral.com/forums/showthread.php?t=234797

Hopefully this helps someone with their rebuild, upgrade, or just plain answers a question for them. Biggest trouble I had was the diagrams showing stuff being added that shouldn't of been. I also highly recommend "Gpop Shop". They were EXTREMELY friendly and didn't get pissy when I asked questions. They also have turbos for sale, but their site can be tricky to navigate at 1st and confusing if you don't know EXACTLY what you're looking for. The GT2860RS wheel and rebuild kit were from ebay, but the wheel is Garrett. I ordered the GT2860RS compressor housing from ATP Turbo. I replaced BOTH piston rings from the ebay kit with ones from Gpop Shop as I feel their quality will be better, and obviously the step gap ring isn't in the kit ;ol; The 360 thrust plate and all the other parts appear to be solid quality. I bought one of the $70 kits. Once everything is broken in, I'll post a video of some runs.

 

[condaddy]

great write up, so what is this turbo equvilant to a td04 15t 6cm? and what are the benifits of just using to a 360 degree thrust washer on a turbo rebuild?

 

[Pontius DIO]

great write up, so what is this turbo equvilant to a td04 15t 6cm? and what are the benifits of just using to a 360 degree thrust washer on a turbo rebuild?

I think Bogan remember's which Mitsubishi turbo is similar. But the exhaust housing being ported and the actual GT2860RS compressor housing should make it better by a couple ponies. Will have to wait for a dyno run to know for sure. No idea how much boost it'll handle safely.

The 360 degree kit is recommended once you start going above stock psi level as higher boost level puts more load on the turbo, and eventually the weak thrust collar won't keep in/out movement in check. Then the rings will get eaten and by that time it's a goner.

The 360 degree thrust plate is solid all the way around and stops movement of the shaft under high loads. If you look at a stock thrust plate and a 360 degree plate, there's a massive difference. Very easy to do the upgrade. If you do the kit, get it balanced. Gpop charged $65 which was very fair. They also acid dip the exhaust wheel so it'll look like new. ;ol;

 

[condaddy]

Well now I just need to figure out what turbo set up I'm going to go withbut which ever it is it's going to have a 360 thrust plate!

 

[Pontius DIO]

In all honesty, you'd probably have a cheaper and easier time going with a TD04. (whether it's usable power band will suit you, I dunno) I went this route for something different, and the way the car was running before the turbo quit, wasn't bad at all as it was beating cars I didn't think it would. I'm hoping to basically have a healthier version of the T25. I'm not a fan of lag, or high rpm spooling to move 4cyl cars, so keeping the exhaust wheel smaller was a logical step as I like early torque in the power band.

 

[condaddy]

Well I like to do things different than others to, I wanted to upgrade my t25 because it has a bigger exhuast housing and than my td04 it only 5cm, and either the t28 bogans got or a 19t would be plenty of power for my autobox maybe to much, so I wouldnt be going any bigger than either of those. But I want get some kind of a stage 5 tune so turbos my next big thing.

 

[Tripple]

T28

How much money will you have into this t25??? Do you think it will out perform a tdo4??? I won't be driving my car threw the winter months and may try to do this to my t25???

 

[Pastry]

fantastic write up, thanks Pontius. I'd like to tackle this but it sounds a bit beyond me. But it'll be interesting to hear how you go.

 

[bogan]

Nice job Pontius,

I'll be interested to see how it goes. Are you going to go with a tune or stick with the MBC ?

I like the big diagram picture of the turbo in pieces

 

[Pontius DIO]

How much money will you have into this t25??? Do you think it will out perform a tdo4??? I won't be driving my car threw the winter months and may try to do this to my t25???

Compressor housing=$119
http://www.atpturbo.com/mm5/merchan...tp&Product_Code=ATP-HSG-054&Category_Code=GCH

360 Degree rebuild kit= $67 (they lowered the price!)
http://www.ebay.com/itm/280898944404?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

GT2860 Comp. Wheel=$60
http://www.ebay.com/itm/Brand-new-P...es&hash=item1e5f17312e&vxp=mtr#ht_1092wt_1200

Balance @Gpop= $65
http://gpopshop.com/services/turbo-balancing/

Machining the Center housing= $?? Depends on who you know or what's available. It cost me $6 for two Dremel grinding stones from Lowes. Used 1 for all the grinding, then the second one to clean up the edges. Take your time and be consistent. Make sure you have at least as much of a spacing as the factory wheel had so if it ever fails, the wheel won't grind into it. More than likely, the wheel will hit the compressor housing before that though if failing warnings are ignored.

That's the prices for doing a HEALTHY T25. (EXAMINE EVERYTHING CAREFULLY BEFORE SENDING TO BALANCE) I paid extra for a new exhaust wheel/shaft. I also needed a new heat shield, and splurged for the Stepped gap ring. Had I known the exhaust wheel was bad, I would of bought a used one and sent that for the balance ;ol; Didn't include shipping as that will be different for everyone. I was out performing TD04 cars with the stock T25, so yes it should be a quicker car. But keep in mind I've removed seats, bigger FMIC, MBC, porting, hood vents, etc. so it's not a level playing field. If you want this to do better than a TD04, port the exhaust housing's runner or go with a bigger 6cm exhaust housing. It's considered as a performance upgrade. It won't be a huge difference, but it's enough for me and I get to keep a relatively stock set up as far as appearances go.

Well I like to do things different than others to, I wanted to upgrade my t25 because it has a bigger exhuast housing and than my td04 it only 5cm, and either the t28 bogans got or a 19t would be plenty of power for my autobox maybe to much, so I wouldnt be going any bigger than either of those. But I want get some kind of a stage 5 tune so turbos my next big thing.

Consider lightening the car. That's like adding more HP and it's basically free until you add a lexan rear window or light weight hood. A bigger exhaust wheel adds more HP up top, and might be better for your auto as it won't be as much stress down low, especially if your tires hook.

fantastic write up, thanks Pontius. I'd like to tackle this but it sounds a bit beyond me. But it'll be interesting to hear how you go.

Thanks. It's really not hard to do. Look at my diagram, then look at one of the "master" diagrams everyone else uses, it should be very simple to follow mine. Numbered in order for ease of 1st timers.

Nice job Pontius,

I'll be interested to see how it goes. Are you going to go with a tune or stick with the MBC ?

I like the big diagram picture of the turbo in pieces

The link for the rebuild kit has the "master" diagram that I reworked, so you can see what I cleaned up an modified. Going to stick with MBC for time being (gonna have to get used to having power again :cheesy. Will probably keep boost lower @10-12psi to see how it behaves and make sure there are no abnormal noises. Then have to get a connector for T5 Suite, as well as doing the fuel pump, FPR, MAP sensor, etc. so I'm working on it ;ol;

 

[Pontius DIO]

I forgot to mention, if you plan to rebuild your T25, clean the inside of the center housing THOROUGHLY! What I did that worked well was I used Oven Cleaner (has LYE in it which is very caustic but removes oil sludge on cast iron wonderfully), let it sit for 5 minutes, then used Foam Engine degreaser. If sprayed correctly, the foam pillows out all the gunk if you spray a steady supply in. Repeat with lye if any gunk is still present after rinsing out foam. Once the area inside that the oil resides in has CLEAN walls, you can rinse it out with water. But it's a good idea to dry it immediately so it doesn't start rusting, which it will. Can coat it's insides with some clean engine oil if it's going to sit a while. It's also a smart idea to spray lye into the oil feed line so any coking inside is dislodged, then chase out with a garden hose.

 

[Pastry]

Really sounds like one of those things that make sense once you get stuck in. I guess it doesn't sound that difficult, and it's a huge saving (up until something goes wrong, at least..!)

Probably worth trying to source a T25 from a wreck and giving it a go, I suppose! Cheers again for the awesome write up.

 

[Pontius DIO]

Got the new housing today and it apparently needs a back plate adapter ring and a hardware kit to mount to a T25 CHRA which bumps up the price another $70. ATP's site "says" this adapter ring is only needed for a GT2560R-GT30 CHRA, but after calling them they said it'll fit the T25 as well. Make SURE that which ever style housing you get (I ordered the T04B style), that you tick the box for the correct ring and hardware kit (i.e. I'd tick the T04B style for the ring and hardware set), matching the housing. Good news is it'll fit other T XXXX CHRA's so a future upgrade can be cheaper. This housing is much healthier than a stock T25's, so it's a no brainer in my case to upgrade over porting out the stock comp. housing. Always a learning experience! :cheesy:

Adapter Ring:

http://www.atpturbo.com/mm5/merchan...tp&Product_Code=atp-hsg-060&Category_Code=HAC

The adapter ring bolts to the comp. housing with the hardware kit, then you use the retainer ring (giant C-clip) from the rebuild kit (or reuse a factory ring) to mount the CHRA to the adapter ring.


Hardware Kit:

http://www.atpturbo.com/mm5/merchan...tp&Product_Code=ATP-HSG-062&Category_Code=HAC

 

[Pontius DIO]

Housing Pics

The adapter ring and the hardware kit came today and thankfully everything fits OK. Even though the GT2860RS housing says Garrett, the ring may or may not be Garrett. It's a higher quality aluminum and it's fit is good, but it's not as tight of a fit as I'd like to have (talking a couple thousandths off). When looking at the wheel's inducer, it's clearances appear a little tight on one end. So best bet is to set the CHRA with the compressor wheel "UP" and set the housing on it. Maybe use some thin plastic to shim the wheel centered then carefully tighten 1 bolt on each retaining bracket carefully, then go back and tighten the 2nd one (prevents movement). Even though the wheel was spinning freely in the housing, it MUST be centered. It's attention to little details that help in the long run ;ol;

Both Housings side by side:

Adapter Ring and Hardware Kit. The shroud is much larger and the interior snail shell runner is noticeably wider, which means this housing will easily out flow a puny T25's comp. housing.

Even though they both have 2" OD, look at the difference in wall thickness at the outlet.

Rear view:

One thing missing from the GT2860RS housing is this vacuum/boost port (threaded nipple removed). Either modify your housing or find a new location to get a signal from.

Also missing is the Wastegate bracket. Thankfully the new housing has a raised boss that could either take a welded on aluminum bracket, OR do like I will and make a steel bracket that's "Z" shaped and will attach to the 2 bolts from the adapter ring's side.

All in all it's been frustrating at times being a 1st timer, but the pay-off is a sub $500 "brand new" turbo which is basically an $1100 GT2860RS with a small exhaust wheel that's basically a direct bolt in. Just need to fab up a 3" elbow and some pipe to mate the the factory air filter box and see how she runs :cheesy:

EDIT: This housing is considered to be a T04B housing. They have a 2 bolt "IN" housing, but if you reuse the stock intake pipe, you'll create a restriction. Also, the 2 bolt "IN" pipe had a 3 bolt "OUTLET" end which means you either need a new turbo-to-intercooler pipe/hose, or you'd have to grind the 3 tabs off to make it a smooth outlet to reuse your stock IC hose. There are apparently other style housings, but I know nothing about them, so do your homework before committing to anything.

 

[condaddy]

Is the t25 Exhuast wheel smaller than the td04

 

[Pontius DIO]

Is the t25 Exhuast wheel smaller than the td04

I honestly don't know enough about the TD04, but others do if they decide to chime in and help.

The stock exhaust wheel on a T25 is: 2.09"/53mm inducer and 1.64"/41.7mm exducer. Apparently from a site I'm looking at
http://www.ztechz.net/id1.html
it shows that a true T28 has the exact same exhaust wheel. So consider my turbo build to be a T28 with a different housing and ported exhaust housing, meaning a theoretical bump in HP over a "real" T28 from Garrett. The Chinese ones come with different wheels.

 

[bogan]

but the pay-off is a sub $500 "brand new" turbo which is basically an $1100 GT2860RS with a small exhaust wheel that's basically a direct bolt in.

Just a note,

A gt2860rs will flow +/- 350hp