T28 internals into a T25 housing? [Archive] - SaabCentral Forums

: T28 internals into a T25 housing?


Pontius DIO
06-04-12, 04:32 PM
Ok, I'm going to be looking for an inexpensive upgrade/replacement turbo until funds allow a better quality unit, and rather than a bone yard replacement, I was thinking about this :
Amazon.com: Godspeed Universal T28 Internal Wastegate Turbo Charger: Automotive

What I'd like to do is pull the center section and install it into my T25 housing but have questions:

1. Will it work? The compressor wheel and turbine wheel on this "T28" are smaller ??? than a T25? Am I reading that correctly? In theory wouldn't it be a direct fit?

2. Say I only keep the exhaust housing from the T25 and use this T28's compressor housing + new intake coupler, Think everything would work? Would there possibly be issues with the bearings being different sizes and therefore the center section might not fit the T25?

3. If I just ran this turbo as-is without frankenbuilding between the 2, I'd need a new down pipe flange to fit, right? :confused: Does a flange get welded to that 5 bolt plate? On the T25 the outlet hole is integrated, but this has that removable plate (obviously needs clocking too) still don't know enough about these yet, so asking in advance ;ol;

4. Anyone know of any direct fit T28 or Big T28's for sale at a reasonable price? If I pull my T25 to convert it, gotta buy the wheel, the GT2861RS housing, get a rebuild kit, then ship it off for the balancing which will be over $300 and the car will be out of commission for a while. If i buy a used T25, still gotta worry about it's bearings as well. Thoughts?

smut
06-04-12, 04:44 PM
It looks like the down pipe could be welded directly onto that 5bolt plate. You still need a 3' downpipe and Id be sure that with that plate that the wastegate can open fully.

Pontius DIO
06-04-12, 06:12 PM
It looks like the down pipe could be welded directly onto that 5bolt plate. You still need a 3' downpipe and Id be sure that with that plate that the wastegate can open fully.

Haven't seen enough of that style in-car to visualize how they do them. IF the flange just welds to the plating, then it opens the door for a larger hole to be bored into the plating which might be nice, although that "rectangle" looking inside looks like a mess for clean exhaust flow. I doubt I'll mess with a 3" down pipe though. Would probably go with a 2.5". Unless I get a BIG turbo someday which I doubt, not going to bother with 3". If it spools fast and EGT's are normal or acceptable, not going to bother with the large pipe just because everybody else does it.

Earlier a car on the highway pulled in front of me going 60 MPH, when I was doing 68, it realized I was there and let me pass. I mashed on it in 4th and was @110 in a couple sec without realizing. Seeing as how it's just a T25 and 16 PSI, the car moves plenty fast with the stock DP. A bigger T28 and 2.5" should suffice. I just don't like the idea of giant pipes on a daily driver with a tiny engine.

If the plate's hole is bored to 2.5", and the DP is 2.5", there will be less restriction at the housing as everything matches. Most smaller turbos have a 2" to 2.25" hole, then dump to a larger downpipe- meaning the turbo's hole is the restriction.

Would be nice if I could reuse the Garrett housing as it's a better grade of cast iron than the China charger would have.

bogan
06-04-12, 07:15 PM
Ok, I'm going to be looking for an inexpensive upgrade/replacement turbo until funds allow a better quality unit, and rather than a bone yard replacement, I was thinking about this :
http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=464984110&adtype=1&size=1x1&type=3&campid=5336714586&toolid=10001 Amazon.com: Godspeed Universal T28 Internal Wastegate Turbo Charger: Automotive (http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2FGodspeed-Universal-Internal-Wastegate-Charger%2Fdp%2FB004ASRMN6&tag=5336714586-20&linkCode=ur2&camp=1789&creative=9325)

What I'd like to do is pull the center section and install it into my T25 housing but have questions:

1. Will it work? The compressor wheel and turbine wheel on this "T28" are smaller ??? than a T25? Am I reading that correctly? In theory wouldn't it be a direct fit?

2. Say I only keep the exhaust housing from the T25 and use this T28's compressor housing + new intake coupler, Think everything would work? Would there possibly be issues with the bearings being different sizes and therefore the center section might not fit the T25?
I'm no expert but this is my understanding,
Don't pull it apart. It will not be a direct fit and you need to be highly experienced with doing this. Your T-25 housing needs to be bored out to accept the bigger internals.

3. If I just ran this turbo as-is without frankenbuilding between the 2, I'd need a new down pipe flange to fit, right? :confused: Does a flange get welded to that 5 bolt plate? On the T25 the outlet hole is integrated, but this has that removable plate (obviously needs clocking too) still don't know enough about these yet, so asking in advance ;ol;
You can use one of these "v-band" adaptors for the exhaust.http://www.ebay.com.au/itm/GSP-T25-T28-GT25-GT28-5-BOLT-3-v-band-TURBO-OUTLET-DOWNPIPE-FLANGE-ADAPTER-/400278786222?pt=Motors_Car_Truck_Parts_Accessories&hash=item5d327990ae
Clocking the turbo is a piece of cake. Don't even worry about that part.You just loosen the 4 bolts on the compressor housing and spin it.
I'm no sure but I also think the oil and coolant lines will be different.
You can use this http://www.ebay.com.au/itm/Turbo-Oil-Water-Line-Kit-Garrett-T2-T25-T28-Journal-Bearing-Turbo-w-Gasket-/120887740793?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c25788979

4. Anyone know of any direct fit T28 or Big T28's for sale at a reasonable price? If I pull my T25 to convert it, gotta buy the wheel, the GT2861RS housing, get a rebuild kit, then ship it off for the balancing which will be over $300 and the car will be out of commission for a while. If i buy a used T25, still gotta worry about it's bearings as well. Thoughts?
In saying all this, for a few hundred more you can get a proper "Garrett Big T-28" built by Garrett. And its all a direct fit.

Just out of curiosity give "David in Tallahassee" a pm. He is "Captain T-28"

Pontius DIO
06-04-12, 11:57 PM
On a budget so trying to save for now and avoid paying more for something than it's worth whenever possible. Thinking of getting another T25 and just doing the conversion myself, then shipping it off for balancing at the Pittsburgh turbo place. Can get a T25 for $75 used, wheel for $60, housing for $100, then figure on $60 for the balance, whatever a gasket kit costs. Probably another $50 in shipping costs. Would rather do that over the period of a couple weeks than buy a pre-made Garrett that'd be way more.

Might be kind of fun doing it this way. Could keep the current turbo on the car too. Thinking I'll just go this route, even though it'll take a little longer. Fire up the rotary rasp and make things more efficient too :cheesy:

Guess I could take pics or do a shortened video on the clean up, tear down, what's being done and why, porting of the exhaust housing, and possibly some porting of the compressor's exit pipe, clean up and interior/exterior polishing, then reassembly. Actually I'm getting excited thinking about it, so this will be the way to go. Forget that china charger junk at the start of the thread. This way I'll get the Big T28 in true Garrett form. Probably the biggest turbo I'll go with. Rest of the work will be suspension, maybe some head and intake runner porting eventually. Figure 350 HP in a streetable RPM range will make this thing a beast and kill the big turbo guys who are missing the low end. I'm psyched!

bogan
07-04-12, 02:27 AM
Pontius,With all due respect,

I'm not a fortune teller, But I can predict exactly how this thread will end.:cry:

Goodluck.

Pontius DIO
07-04-12, 03:26 AM
Pontius,With all due respect,

I'm not a fortune teller, But I can predict exactly how this thread will end.:cry:

Goodluck.

Me no understanda~? You sipping el bottle?

Pretty sure i can do the wheel and the compressor housing from a GT2861RS myself, then ship off the center section to get balanced? Porting will be tasteful and uniform.

Yours still has the factory T25 exhaust wheel right? Or are you running another turbo?

bogan
07-04-12, 03:41 AM
If you can build your own T-28 I'll will be very impressed.

Mine is the full 2860rs hot and cold wheel conversion.

And yes I am drinking :p

Pontius DIO
07-04-12, 05:07 AM
It's well within my capabilities as it'd only be the wheel and compressor housing. If the turbo is any good I'll hold off on the rebuild kit, otherwise I'd just follow a video tut so nothing breaks.

What size wheels do you have in the exhaust (.86?) and compressor side? What's the difference with keeping the T25 exhaust wheel?

smut
07-04-12, 07:10 AM
Im no expert but its been mt understsnding that as soon as you go stg 3 you have to get a 3" downpipe to avoid blowing your turbo? THat t28 pushes a lot more heat than a t25,just dont want you to lose your money.

Pontius DIO
07-04-12, 10:04 AM
Im no expert but its been mt understsnding that as soon as you go stg 3 you have to get a 3" downpipe to avoid blowing your turbo? THat t28 pushes a lot more heat than a t25,just dont want you to lose your money.

The "T28" I'll end up with will be a GT2861RS compressor housing and compressor wheel mounted to the T25. The exhaust side I'm not going to touch. (maybe down the line it'll be worth it to throw in the slightly larger exhaust wheel, but not worth it to me now)

The turbo won't blow up because i'm using a 2.5" DP. Maybe if I tried pushing 35 psi or something ridiculous like that, something in the engine might not like it, but the turbo won't implode from 2.5" DP alone. Think Bogan said David in Talahassee runs one as well with a similar turbo set up.

bogan
07-04-12, 10:08 AM
2.5 dp with no cat.

If you run a cat it needs to be 3'.

Pontius DIO
07-04-12, 11:21 AM
2.5 dp with no cat.

If you run a cat it needs to be 3'.


Which exhaust wheel do you have Bogan? Do you have the .64, or the .86 hot side wheel from the GT2861RS? Figure the factory T25 wheel is near identical to the .64, so low end should be strong with the T25/GT2861 mash up with a touch more up top.

How much of a delay in spool is there with a .86 HS wheel?

jakejm79
07-04-12, 07:36 PM
Bogan I think he plans only doing the hybrid T25/T28 upgrade by just upgrading the compressor side and leaving the exhaust side the same. There should be no machining necessary since the GT28RS housing will accept the T28 wheel fine and the exhaust side will be left alone. If he plans to upgrade the exhaust side wheel then he will face some custom machining which could or could not be beyond his skill level. Weird those posts weren't above when I read this.

bogan
07-04-12, 10:23 PM
Which exhaust wheel do you have Bogan? Do you have the .64, or the .86 hot side wheel from the GT2861RS? Figure the factory T25 wheel is near identical to the .64, so low end should be strong with the T25/GT2861 mash up with a touch more up top.

How much of a delay in spool is there with a .86 HS wheel?
I'm not absolutely certain of my spec's. (I just bolt stuff on and press the pedal). David is the numbers man.
What I do know is that the "big T-28" has the exact same hot and cold wheels of the gt2860rs.
The hot wheel is a 54mm. With a .86 A/R housing.( David may correct me on this )
The difference between the turbo you are building and the "big T-28" is about 50hp.
You will be lucky to crack 300whp.

I've heard David say before that the turbo that you are taking about building will be the equivalent to a Mitsu 6cm 15T.


I spool @ 2800 :cool:


Bogan I think he plans only doing the hybrid T25/T28 upgrade by just upgrading the compressor side and leaving the exhaust side the same. There should be no machining necessary since the GT28RS housing will accept the T28 wheel fine and the exhaust side will be left alone. If he plans to upgrade the exhaust side wheel then he will face some custom machining which could or could not be beyond his skill level. Weird those posts weren't above when I read this.

I didn't know that Jake.;oops: I thought both sides had to be machined.
To be honest I've never pulled apart a turbo. And probably never will. Somethings I like to leave to the experts ;).

jakejm79
07-04-12, 11:16 PM
You only have to machine both sides, if you don't swap in a GT28RS compressor housing, though at that point the housing becomes the bottleneck, so it is just easier to replace it.

Pontius DIO
08-04-12, 02:50 AM
Is there seriously a 50Hp difference between running a .66 and .86 exhaust wheel? Thought the larger wheel was just more for top end breathing where the .64-.66 would just lower the boost response and limit top end breathing?


Boring the exhaust housing then polishing is doable from what I can tell if you're SUPER careful and mic everything, and the new size is IDENTICAL to the GT2861RS opening and has the proper clearances to allow for any expansion. Gotta keep the rotary rasp moving in a full circle (counter-clockwise in the bore) constantly inside the inner bore and never let it make flat spots or uneven cuts, it's just a matter of patience. Cast iron is easy to work with, but takes awhile to grind. It's just the housing's hole after all. As long as there is enough room that nothing touches the blades when heated up, might give it a go. But then again it's a street car and the smaller wheel makes more sense. Maybe if the car lost another 200+ pounds and had the steeper 4.45 gear set it might be worth the trade off of higher spooling. Maybe a future consideration....


Another thing, I'm still running the AC compressor. It's a tight fit between the turbo's inlet pipe on the T25 and the back of the compressor. Is there any issues sticking the GT2861RS compressor housing in there and putting whatever size 90 degree coupler on? Will probably run two 90's and section of pipe between them- 90 off the compressor pointing up, to a several inch long pipe, then another 90 off it to a jump-size to the factory air filter box.

Pontius DIO
08-04-12, 03:05 AM
I spool @ 2800 :cool:

Got you beat by almost 800 RPMS :cheesy:


To be honest I've never pulled apart a turbo. And probably never will. Somethings I like to leave to the experts ;).

They aren't that complicated. It's basically a single shaft with 2 wheels at opposing ends. There's hardly anything to replace in the kits. Think a lock ring remover is the only special tool needed? Gonna jump in with both feet and give it a go:
http://cdn100.iofferphoto.com/img/item/193/566/164/garrett-t2-t25-t28-turbocharger-rebuild-kit-97e35.JPG

bogan
08-04-12, 03:42 AM
Got you beat by almost 800 RPMS
You see full boost @2K ?

I begin to spool @2200, I am at full boost @2800.
And I run a cat

Pontius DIO
08-04-12, 05:47 AM
You see full boost @2K ?

I begin to spool @2200, full boost @2800.
And I run a cat

I can hear it spooling *around* 1700 and full boost (16PSI) around 2200 (it's about 11PSI @2k). Just got back from a trip to the gas station and that's what I was getting.

The oil issue is getting worse so it might be affecting the turbo now, even though it sounds and performs OK. Gotta remember to check the air filter in daylight and see if it's clogging after 5k miles as I read on Garrett's site that it can cause more oil to get past the turbo (something about the pressure). Seems odd that the oil is leaking in all of a sudden but it's not smoking. Get some tufts of smoke though :cry:. Not looking forward to more work on it, but @167k miles it's to be expected.

bogan
08-04-12, 07:20 AM
Is there seriously a 50Hp difference between running a .66 and .86 exhaust wheel?
I no expert. As I say, David is the brains, I just bolt stuff up and push the pedal.
But I am lead to believe (and have read several times) that the difference is alot.


It sounds like your turbo is cactus. :-(

BobSaabit
08-04-12, 08:10 PM
Pontius:

If you're looking for a replacement, on a budget, and only going to get 300HP from the setup you will have (and I don't know... just reading suggestions here) would it make more sense to just go with a used TD04-15t... then upgrade that to a 19t later if you want more?

Pontius DIO
08-04-12, 08:45 PM
Pontius:

If you're looking for a replacement, on a budget, and only going to get 300HP from the setup you will have (and I don't know... just reading suggestions here) would it make more sense to just go with a used TD04-15t... then upgrade that to a 19t later if you want more?

Think I'll get another T25 for $50-75 (which is a steal if you think about it). If it's good enough shape I'll throw it in the car for the time being and it'll serve as a spare parts/backup turbo in the future, then the left over T25 will get built into a T28. Just makes more sense having 2 T25's then messing with a TD04 at this point (if the car already had a TD04 it'd make more sense). If the car can get a real 300 to the wheels or more it'll be a beast of a daily driver with all that low end power and early boost ;ol; Still haven't decided if the larger wheel + delay in boost is going to be worth extra 50hp that takes too long to come on.

David in Tallahassee
09-04-12, 08:44 PM
Honestly, I'm too tired to wade through this whole thread. However, I will say this:

1.) To my knowledge there is no such thing as a "2861" Garrett turbo.

2.) The big 28 requires, not only machining, but EXPERT machining to accept the full T28 hot AND cold wheels.

3.) Without the hot side conversion, you will have a hybrid T25 / T28 which will be about like a TD0415T 6CM in terms of power. In other words, call it 300 crank.

D-

David in Tallahassee
09-04-12, 08:46 PM
Got you beat by almost 800 RPMS :cheesy:

The difference is that Bogan's snail will hold a solid 24PSI to 6.5K. He's got you beat there by about 2K RPMs.;ol;

Further, 2K RPMs will only be seen one time in the course of a multi-gear run and that would be if you went from a dig.

D-

Pontius DIO
09-04-12, 09:46 PM
Honestly, I'm too tired to wade through this whole thread. However, I will say this:

1.) To my knowledge there is no such thing as a "2861" Garrett turbo.

2.) The big 28 requires, not only machining, but EXPERT machining to accept the full T28 hot AND cold wheels.

3.) Without the hot side conversion, you will have a hybrid T25 / T28 which will be about like a TD0415T 6CM in terms of power. In other words, call it 300 crank.

D-

1. So now a GT2861RS doesn't exist?

2. Not machining the cold side. Will put a GT2861RS compressor housing on the T25, or is that not possible now?

3. From what I've seen of actual "True" T28's (being sold as actual T28, not a hybrid T25), they have smaller wheels in .46 range, so I'm getting confused.

What I'm going to do (based on the info in the other thread assuming it's factual as now I'm not sure) is buy:

GT2861RS CS wheel
GT2861RS Compressor housing
Another T25
Rebuild kit if needed

Are you saying that with the cold side GT2861RS housing that this will have the same HP potential as a ported-to-fit T25 cold side housing? No offense, but that seems hard to believe there's no difference between a GT2861RS cold side housing and a ported T25 cold side housing.

-The comment about the spooling against Bogan's was joke as they are obviously very different turbos. But the turbo does spool and build boost as stated after the car is warmed up and been running, and seems consistent as far as I can tell, so I'm not sure what your getting at nor do I appreciate the condescending nature of the comments. Gonna assume you were tired and cranky.

jakejm79
10-04-12, 12:57 AM
1. I'm not sure where the talk of a GT2861 came from? Like David says it doesn't exist (at least not a genuine Garrett unit, they do a 2854, 2859, 2860, 2860RS (aka disco potato), 2871 and 2876.

2. If by 2861, you mean 2860 then yes you can do that, it is the T25/28 hybrid and like stated will net you about the same performance has a TD0415T, seems like a lot of work, money and room for error when you could just bolt on a TD04.

3. I believe the difference is around 5-10% between machining the housing or using one from a 2860, a couple of hundred $ less for machining tho, whether the machining is within your skill level that is up to you to decide.

I think David's comment is perfectly valid, he is stating that holding max boost for a longer period of time is more important than spool up being a little earlier, once you get off the line you will never see 2K again.

Pontius DIO
10-04-12, 06:01 AM
1. I'm not sure where the talk of a GT2861 came from? Like David says it doesn't exist (at least not a genuine Garrett unit, they do a 2854, 2859, 2860, 2860RS (aka disco potato), 2871 and 2876.

2. If by 2861, you mean 2860 then yes you can do that, it is the T25/28 hybrid and like stated will net you about the same performance has a TD0415T, seems like a lot of work, money and room for error when you could just bolt on a TD04.

3. I believe the difference is around 5-10% between machining the housing or using one from a 2860, a couple of hundred $ less for machining tho, whether the machining is within your skill level that is up to you to decide.

I think David's comment is perfectly valid, he is stating that holding max boost for a longer period of time is more important than spool up being a little earlier, once you get off the line you will never see 2K again.

Stupid meds make short term memory iffy at times and apparently I can still get confused if I'm not careful. Was meaning 2860RS. When he wrote that earlier it went over my head at the time as I was thinking 2860 so here's one for the typo police.

He should of read the entire post. The comment about spooling earlier had nothing to do with anything or anyone else. I was playfully teasing Bogan. But if David feels the need to jump in and "put me in my place" because he built the turbo, that's entirely on him. Only way holding boost at higher rpms for more than a couple sec is important is if top speed is priority. For me it runs out of gear quickly as it makes 16PSI from 2200 until redline, so spooling later and holding a high boost isn't important to me as I'm pretty sure I'd already be in another gear by that time.

Don't want a TDO4. Would need an older style from a 9000 to eventually get a -19 in it and after it's said and done would probably cost more to convert and I'd miss out on having spare parts for it. If I stay away from the hot side, I could do the cold side housing, wheel, rebuild kit, & balance for under $400 (including the price of a spare T25)- which would be ALL Garrett stuff and basically a new unit. Seems better than spending 600-1000 elsewhere for something I can do mostly in house. I appreciate the sentiment, but even a full on swap I think I could keep under $500. Guys running a big Gt30 series, spacer, removing the AC unit, running custom IC pipe, oil and water lines, etc. end up spending WAY more. Still not sure what to do on the hot side yet, meaning if it's worth it or not.

bogan
10-04-12, 06:58 AM
Pontius, Don't take nothing to heart.
David is actually one of the nicest blokes you will ever meet. But he knows his stuff back to front and inside out.

Bro, we are just trying to point you in the right direction. And we don't want to see you waste your time and money. But in saying that you seem like a very smart guy and a bit of a "thinker". And there is nothing wrong with being a "thinker or questioning things.
And you may very well surprise us all.

I'm like you, and I try to do everything myself, but somethings are best left to the experts

And, If you want reliable performance, it's going to cost ya";).

And I'm drinking again :p

David in Tallahassee
10-04-12, 07:19 AM
1. So now a GT2861RS doesn't exist?

2. Not machining the cold side. Will put a GT2861RS compressor housing on the T25, or is that not possible now?

3. From what I've seen of actual "True" T28's (being sold as actual T28, not a hybrid T25), they have smaller wheels in .46 range, so I'm getting confused.

What I'm going to do (based on the info in the other thread assuming it's factual as now I'm not sure) is buy:

GT2861RS CS wheel
GT2861RS Compressor housing
Another T25
Rebuild kit if needed

Are you saying that with the cold side GT2861RS housing that this will have the same HP potential as a ported-to-fit T25 cold side housing? No offense, but that seems hard to believe there's no difference between a GT2861RS cold side housing and a ported T25 cold side housing.

-The comment about the spooling against Bogan's was joke as they are obviously very different turbos. But the turbo does spool and build boost as stated after the car is warmed up and been running, and seems consistent as far as I can tell, so I'm not sure what your getting at nor do I appreciate the condescending nature of the comments. Gonna assume you were tired and cranky.

Dear Sir,

Please forgive the continued condescending attitude. I am still tired. Tired of saying the same things over and over. For the record, it simply does not profit me enough to continue doing it. However, for the benefit of my customers I shall respond to these points.

A 286"1" never did exist to my knowledge and I believe that you will find it an impossible task to locate a statement made by me which states that it did. For reference please review this:

http://www.turbobygarrett.com/turbobygarrett/turbochargers

You will note that no 286"1" designation is shown by Garrett.

Of course simply bolting on the T28 cold side will still give you the same hybrid as I've stated it would in the past. With a 286"0" cold housing you might squeeze 310 crank from that combo.

While you are on Garrett's website, spend several hours on their tech section. After truly comprehending all of that information you will find that the A/R which you state as if it were a "wheel size" is actually a RELATIONSHIP.

I fully appreciate the "budget beater" plan. As a matter of fact, I think it's great. I am bent that way myself. Why else would I still be running manual boost control?

Right now though, I recommend that you spend some time educating yourself with facts which may be difficult to get from forum responses. Once you get a solid grip on the fundamentals of turbocharger sizing and how it impacts airflow you will be able to answer all of your own questions simply by reviewing the compressor maps. My personal recommendation is that you take these steps BEFORE you decide what you are going to buy as a turbo upgrade.

Carry on.

D-

jakejm79
10-04-12, 09:38 AM
Don't want a TDO4. Would need an older style from a 9000 to eventually get a -19 in it and after it's said and done would probably cost more to convert and I'd miss out on having spare parts for it. If I stay away from the hot side, I could do the cold side housing, wheel, rebuild kit, & balance for under $400 (including the price of a spare T25)- which would be ALL Garrett stuff and basically a new unit. Seems better than spending 600-1000 elsewhere for something I can do mostly in house. I appreciate the sentiment, but even a full on swap I think I could keep under $500. Guys running a big Gt30 series, spacer, removing the AC unit, running custom IC pipe, oil and water lines, etc. end up spending WAY more. Still not sure what to do on the hot side yet, meaning if it's worth it or not.
What are your horse power goals? You mention you don't want Td04 since you would want a 19t, but then you talk of doing a T25/28 hybrid, which would only but you in the 15t ballpark. For $400 you could bolt on a Td04-15t and have the same level of performance has the T25/28 hybrid with none of the headache (or risk) of doing the work yourself.
If you eventual plan is to go: T25>T25/28 Hybrid>Full T28 then personally I think that's a waste, you are going to end up paying to get it balanced twice, and close to twice the work.
Figure how much you are willing to spend max and where you want to end up horsepower wise and go from there.

Your current T25 holds 16 PSI from 2200 to red line in every gear?

Kei
10-04-12, 10:30 AM
a T25 will hold 1 bar (15/16psi) at 6k but it's beyond the choke line on the compressor map so its well inefficient at that point and will generate an awful lot of heat.

I too am of the camp that won't bother with the TD04. (I even had one with all the parts needed to fit it, lived under my bed for a year before i sold it on to a friend) I wanted a Gpopshop Big T28 too but i can't see the point in it for me as it's beyond where i want to go. I don't want to start messing with my fuel system as it'll throw everything out. (mpg on the SID potentially less efficient etc) A hybrid T25/28 like pontius is suggesting sounded like the ideal turbo for me as it would be less stressed at the top end of stage 3 vs a standard unit. I swear i've seen some dyno plots somewhere for the hybrid achieving around 320 crank. Considering people somehow managed to squeeze 340hp out of a TD04-19T built around a no.5 housing, makes me wonder if its something to do with the actual wheel design rather than wheel size. (number 5 being a 5 sq.cm housing vs the T25 .49a/R which equates to 7 sq.cm)

A T25 hotside
http://i1142.photobucket.com/albums/n605/_-Kei-_/SAAB/Mods/IMG_3550.jpg

Vs a TD04 hot side
http://i1142.photobucket.com/albums/n605/_-Kei-_/SAAB/Mods/TD04-4.jpg

smut
11-04-12, 10:47 AM
I think that this is a great thread so I hope you,PONTIUS will continue to post us on your build .Its great to see what can be done on the cheap.I sometimes wish Id taken that route although my HP goals are too high for the T25. CARRY ON!

Demusku
13-04-12, 02:39 AM
I threw a T25 in mine untill i had the money to do the full T28 upgrade, think it was $800. I wanted to go with a direct fit since i dont have much time to play with making things work. I've had the T28(both wheels changed) for about a week now and so far im very happy with it. Have cold air intake and stock exhaust, still waiting for my exhaust to get here, and no tune yet. But with this setup spools about 2800 rpms and hold boost well through out all gears although i only had her up to a little over 100mph.

IDK if this helps anything i read through kinda quick but it felt a bit like a debate i was having with myself on what to do with my turbo after the original crapped the bed.