I was wondering how much I would be looking to spend on a Ball bearing T28 unit. What specs should I look to have for the quickest spooling possible. My goals are only like 230whp max, but I want to be able to spool really fast. I would like it to become a very good track/autocross unit that can provide very reliable and quick boost. When does the stock T28 unit run out of breath?

What T28 are you talking about? The one off of a S14, S15? Or you going to upgrade a stock T25? :confused:

Well either way....I didn't know you could really upgrade to a ball bearing unit. like take a regular and upgrade. I knew that S13 and up had ball bearing...how much do those units go for? And I guess my next question would be how much would it cost to upgrade a standard unit to ball bearing?

here is my question??? Where can you find a t-28 for sale? I have been looking all over the place and I have not found one for a descent price at all. Someone even told me that he would sell it for $900 for a bone stock one without the ball bearing upgrade. I dont understand, if someone can send me in the right direction. Thanks

You should be able to produce 230whp or close without a ball bearing unit.

For the price of one of those you could probably almost buy an efficent T-3 or hybrid unit.

Well MarkSR20 if you want a T28, the best choice is a new Pulsar GTIR turbo. I can sell you that turbo for $870 shipprd to your door. It is not ball bearing. This turbo can give 280 WHP.

Nexidus you do not need anything more than a BB T25 to get 230 WHP. This turbo spools realy fast. If you are going to run the turbo on a stock SR20DE that is 9.5-1 then get the GTIR T28 because you will only be able to run about 9-10 psi of boost and you will need something larger than the BB T25 to get rid of the hot gases from your high compression motor. Also with a high compression motor and a GTIR T28 the turbo will spool very fast.


Andreas Miko

Originally posted by Andreas Miko
Well MarkSR20 if you want a T28, the best choice is a new Pulsar GTIR turbo. I can sell you that turbo for $870 shipprd to your door. It is not ball bearing. This turbo can give 280 WHP.

Nexidus you do not need anything more than a BB T25 to get 230 WHP. This turbo spools realy fast. If you are going to run the turbo on a stock SR20DE that is 9.5-1 then get the GTIR T28 because you will only be able to run about 9-10 psi of boost and you will need something larger than the BB T25 to get rid of the hot gases from your high compression motor. Also with a high compression motor and a GTIR T28 the turbo will spool very fast.

Andreas Miko

Andreas is right. If you put an S14/S15 Silvia compressor housing and adaptor ring on the turbo, it will support about 300 hp, with full boost by 3500 RPM in 2nd gear.

This is a really good turbo! Garrett will be coming out with a ball bearing version of this turbo with a bigger trim compressor wheel soon. This is the turbo used on the 'Disco Potato' car featured in SCC. 286 whp at 14 psi of boost on pump gas, and 10 psi of boost at 2500 RPM with a cat and only a 2.5" exhaust!

The GTi-R T-28 will support almost as much hp as a T3/T04E hybrid with a 0.63 A/R turbine housing, but spools a lot better

Rob..

Any ideas on when Garret will be releasing it?? Also can you give the trim of the new compressor wheel....

Thanks!!

Originally posted by RacerX
Rob..

Any ideas on when Garret will be releasing it?? Also can you give the trim of the new compressor wheel....

Thanks!!

should be out in about 4 months or so... a bit of a guess.

It will be a 63 trim wheel.

Rob

Rob.... Thanks for the info, I think I might wait for that....maybe :-)


As far as you know, did that turbo pull well (somewhat efficiently) to the neighborhood of 7000 rpm in the "Disco Potato"?..... or does it run into too much back pressure at those RPMs.

I figured 6000 is its best at 14 psi, hopefully I did something wrong when I figured that though. Any help is greatly appreciated....

Thanks!!

Originally posted by RacerX

As far as you know, did that turbo pull well (somewhat efficiently) to the neighborhood of 7000 rpm in the "Disco Potato"?..... or does it run into too much back pressure at those RPMs.


It starts rolling off above 6000 RPM. The Disco Potato has a 2.5" exhaust, though. I think it needs a 3" exhaust.

It still pulls pretty hard up to 7000, but you can feel it rolling off.

How much is the GTiR T28 similar to the S15 stock Turbo. I have a S15 Stock turbo (blown unfortunatly), but it uses the same wheel as a 60 Trim T3. Different shaft diameter I think. But Measuring them with my dial caliper (I have a 60 trim T3 also), they are identical. The slope on the blades "look" identical. Am I correct on this. Will the Disco potato use the same exhaust wheel as the S15 turbo. I am just courious on how it can support almost as much power as a T3/T4 since the turbine wheel is so small. It is visibly much smaller than the stage 1 T3 wheel.

Thanks.

Danny

Originally posted by TurboMiata
How much is the GTiR T28 similar to the S15 stock Turbo.


Same compressor wheel, and that's about it. The S15 and S14 both use a 62 trim T-25 turbine wheel in a 0.64 A/R turbine housing with a ball bearing center section. The only difference between the S14 and the S15 turbos is that the S15 uses an Inco turbine wheel (S14 uses GMR), the S15 uses a turbine housing with a little divider wall built in between the wastegate port and the turbine discharge.

The GTi-R uses a 79 trim turbine wheel in a 0.86 A/R turbine housing.


Will the Disco potato use the same exhaust wheel as the S15 turbo.


No. The Potato uses a 76 trim 'NS111' turbine wheel. This is a 9-bladed turbine wheel that is a newer design than either of the older T-25 wheels. This wheel flows more and is more efficient.


I am just courious on how it can support almost as much power as a T3/T4 since the turbine wheel is so small. It is visibly much smaller than the stage 1 T3 wheel.


A stage I T3 wheel has a 1.898" exducer. A GTi-R turbine wheel has a 1.889" exducer. An S15 wheel has a 1.674" exducer. So, a GTi-R wheel is almost as big on the exducer as a Stage I T-3. However, the GTi-R wheel is in a .86 A/R housing. The bigger A/R is what is letting it flow so much. A GTi-R turbine wheel in a 0.86 A/R turbine housing will flow as much as a Stage III T3 wheel in a 0.63 A/R turbine housing. Strange but true.

WoW... Now I understand somewhat on what you are talking about... Too F'n Bad I have a T3 Flanged setup on my car now. Otherwise I would go with the new T28 Setup.

This Turbo should be a bolt in replacment for any T25 based turbo system. (excluding Mitsu Eclipse, and others that have their own flange setups.)

Going on my Other post It looks like I am going with a 50 Trim, Stage III exhaust, and .63a/r

How Big of a difference do you think the Spool would be on a equally sized T3/t4 vs the T28. Ball bearing vs Ball bearing??

Thanks

Danny

Originally posted by TurboMiata
WoW... Now I understand somewhat on what you are talking about... Too F'n Bad I have a T3 Flanged setup on my car now. Otherwise I would go with the new T28 Setup.


Well, changing flanges is pretty easy, especially when the manifold isn't on the car yet.

BUT, you said that you wanted 350 whp, and that is beyond the reach of the T-28. The T3/T04E hybrid will get that for you. I think that 300 or so is about max for the T-28.



Going on my Other post It looks like I am going with a 50 Trim, Stage III exhaust, and .63a/r


That's what I recommend.


How Big of a difference do you think the Spool would be on a equally sized T3/t4 vs the T28. Ball bearing vs Ball bearing??


I'd say the disco potato ball bearing turbo will spool 800-1000 RPM sooner than the 0.63 A/R t3/T04E combo. This is based on my experience on 2.0L motors, so YMMV.

Man you have me thinking now. Any chance of getting the T28 to fit in a T3 exhaust housing? RacerX told me some people have done that. Also Do you think it will do 300whp on a 1.8 miata motor?

Also I am really considering a S13 or S14 240 in the future. My friend is doing a S14 right now and I want to see how it works out.

300whp with that spoolup will be good enough for me.

Danny

Originally posted by TurboMiata
Man you have me thinking now. Any chance of getting the T28 to fit in a T3 exhaust housing? RacerX told me some people have done that. Also Do you think it will do 300whp on a 1.8 miata motor?


Just have the flange cut off and have a new one welded on. Seriously, that's not difficult work. You can buy the flanges from a Garrett dealer. A decent fab shop would probably do the work for $100 or so. Just make sure you get it TIG welded.

The Potato turbo will do 300 whp on a Miata, I think. It did 286 at 14 psi on an SR20.

Rob

I know i could Cut it and have it welded on. Its not that. I was courious on how a T28 could fit into a T3 Housing like RacerX said.

I think I am going to stick to the 50trim because I want 350whp as I said. I just want to max the motor out on Pump gas and that is actually a little more than it can do, but I dont want to be maxing out the turbo there. If I dont like the 50 Trim I have 6 months to save for the T28 anyway :D Ill let RacerX get it for his car and see how nice it is.

Thanks

Out of whats listed on http://www.turbofast.com.au/GTseries.html would any of them be a suitable uprgrade for the T28? or non of them are compatible?

Originally posted by SucKit
Out of whats listed on http://www.turbofast.com.au/GTseries.html would any of them be a suitable uprgrade for the T28? or non of them are compatible?

I wouldn't use any of those turbos on an SR20