GT28RS swap

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2003.5 Mazdaspeed Protege
So after researching on the forum, I've seen a lot of different answers to whether or not it's a direct replacement to the stock T25. Oil restrictors, clocking the turbo, reroute the IC piping, sock WGA's, etc. I'm not completely sure if I'm even going to get a GT28RS or not yet, but if it's a direct swap, it will definitely be more appealing to me. I'm also pretty sure that my stock turbo is dying, and if I have to replace the turbo, I may as well upgrade at the same time. I am also running stock internals, so any input from anybody running a T28RS on stock internals would be appreciated.
 

Cleverfrog

Binford Tools
Contributor
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1989 RX-7 GXL Blaze Red
why do you think your turbo is dying?

This.

And it IS a direct swap,but, it ISN'T at the same time. You do have to either modify the actuator arm for the disco or modify the stock T25 actuator BRACKET to fit the disco. Down pipe flange is the same and manifold flange is the same. all the oil and coolant lines can stay if you want them to.
 

Preferio

I break stuff.
Contributor
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2003 Mazdaspeed Protege 1660, 2004 Winning Blue RX8, 2005 Mazda6
And I think the oil restrictor is only needed if you buy a cheap, journal bearing turbo... BUT I'm not 100% on that, just seen some chatter here and there.
 

Cleverfrog

Binford Tools
Contributor
:
1989 RX-7 GXL Blaze Red
And I think the oil restrictor is only needed if you buy a cheap, journal bearing turbo... BUT I'm not 100% on that, just seen some chatter here and there.

It IS internally restricted but I still put a restrictor on it for good measure. I also did AN4 oil line for the feed. IIRC all garrett BB turbos are internally restricted.
 

Preferio

I break stuff.
Contributor
:
2003 Mazdaspeed Protege 1660, 2004 Winning Blue RX8, 2005 Mazda6
It IS internally restricted but I still put a restrictor on it for good measure. I also did AN4 oil line for the feed. IIRC all garrett BB turbos are internally restricted.
Are the eBay journal bearing turbos internally restricted?
 
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2003.5 Mazdaspeed Protege
I'm not 100% on my turbo actually dying. But it's making a high pitched metallic ping noise at certain rpms, almost like the shaft is out of balance.

I also wouldn't mind some extra power out of the GT28RS, and now that I have a few extra bucks, I feel that that would be a less expensive alternative to more power than forging. (I don't have THAT much extra money)
 

Cleverfrog

Binford Tools
Contributor
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1989 RX-7 GXL Blaze Red
I'm not 100% on my turbo actually dying. But it's making a high pitched metallic ping noise at certain rpms, almost like the shaft is out of balance.

I also wouldn't mind some extra power out of the GT28RS, and now that I have a few extra bucks, I feel that that would be a less expensive alternative to more power than forging. (I don't have THAT much extra money)

If you havent already, i'd recommend a SSAFC before you get a slightly larger turbocharger. You'll feel more pull from that simple piggyback upgrade than with more boost.

Are the eBay journal bearing turbos internally restricted?

IDK, im not up on ebay turbos.
 
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2003.5 Mazdaspeed Protege
I do have the SSAFC installed already, along with an ebay fmic kit and catless corksport 80mm exhaust. I'm waiting to install my P.E.P. downpipe. If I can find a gently used GT28RS for less than $1100, I'll buy it in a heartbeat.
 

mazdaspeedp

Msp 666 Aka Christine
Contributor
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2003.5 Mazdaspeed Protege
Ya i think a 28rs should be fine on stock internals as long as you dont put the boost up too high.
 

Maxx Mazda

Resident Asshole
Contributor
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Completely Stock P5
It IS internally restricted but I still put a restrictor on it for good measure. I also did AN4 oil line for the feed. IIRC all garrett BB turbos are internally restricted.

Why would you further restrict and already restricted oil line to your turbo?
 

Maxx Mazda

Resident Asshole
Contributor
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Completely Stock P5
Probably because I'm a newb. Are you saying I should drill out my fitting? You know more than I.

The GT turbos are internally restricted, and don't need an additional one. Just run a straight -4AN line to your turbo.
 

highflyin285

PS!
Potential Scammer!
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2003.5 Titanium Mazdaspeed Protege
i dont know what to believe anymore when it comes to using or not using an oil restrictor when running the 28rs. numerous distributors i have talked to say to run a .035" oil restrictor at the end of the -4an oil feed line.
 

jeffmsp

Got Boost?
Contributor
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2003 MazdaSpeed Protege
well look in the dam thing and see if theres a restrictor. if there is then dont worry if theres not then put one on.
 

2.0t03speed

Purple Drank Tuning
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08.5 CWP Speed 3
And I think the oil restrictor is only needed if you buy a cheap, journal bearing turbo... BUT I'm not 100% on that, just seen some chatter here and there.

I don't run any restrictor with my journal bearing 2871. I've always read that journal bearing's can handle higher oil pressures vs ball bearing turbos.