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-   -   T25 Straight Replacement (https://www.miataturbo.net/diy-turbo-discussion-14/t25-straight-replacement-69098/)

bmseven 10-24-2012 10:08 AM

T25 Straight Replacement
 
Hi all from the NOOB :hustler:
Seems the seals blew on my T25 at the weekend as its smoky as hell on idle and there is quite a noticeable bit of play in the shaft. It's only a little T25 AR47 running 6psi rather than a rebuild would I be better swapping it for something else maybe a T25 from a CA18DET, would prefer it to be a straight swap which I believe this would be?
Also had the CAM belt changed last week garage set the timing to 14deg with the TEN & GND jumpered is this correct? should it be 6 what timing is everyone running on their Turbos -Oh and its running Megasquirt :)

Thx in anticipation

cpolly69 10-24-2012 10:15 AM

not a real turbo expert but if you are asking for advice on a replacement turbo for what's on your car now it sounds like you need to learn more about what's there
t25 is nothing but a reference to a flange - .47 ar says a little about the current size and the reference to the nissan motor says something about a potential stock turbo you are thinking about
one of the most common turbos used w/ a t25 flange is the garrett 2560
Turbochargers | Turbobygarrett
spend some time reading here -

bmseven 10-24-2012 10:32 AM

T25 is the Turbo not the flange likely its a 465183 model as found on Saab's. Wont know until its off as cant see any identifiers on whilst its in situ

cpolly69 10-24-2012 03:17 PM

i'm just sayin
if you call garrett - borg warner - mitsu - etc up and say "hey i want a t25 turbo"
they are probably going to say
"which one?" we can do all these turbos with a t25 flange
you just need to know the wheel trim and the a/r (which you already know), and what kind of dp flange you have and if you just take that info to that site and use the search function - it will lead you right to some nice options for replacement
unless you are stuck on an oem turbo from a major car manufacturer for some reason

TheBigChill 10-29-2012 05:34 PM

T2 is a turbine inlet flange type. The number following the "T2" has no influence on the flange size or pattern. T25, T28 both have a T2 flange and only a T2 flange. The GT ball bearing series gives an option of T2 or T3 flange, but are usually offered with T2 style flange.

Chances are, he's using the typical Garrett T25 that Nissan slapped on damn near everything they made pre-1995. This has the extremely common 5 bolt turbine outlet flange. I doubt it is a Saab T25, because Saab used the janky 3 bolt turbine outlet that essentially nobody else used. The difference is easy to see. OP, go look at the hotside of your turbo; how many bolts do you see ? This will determine what other turbos you can use.

Seeing as though you have tunable engine management, there's no reason that you have to stay with the identical Trim and A/R. You simply need choose a turbo that has the same turbine inlet, turbine outlet, and clock/orientation. You will experience the most significant change if you choose to change the Turbine A/R, as it directly affects spool time and RPM dependent performance. Small A/R will spool quickly, but "fall off" at high RPM because it in itself is a source of back pressure due to small A/R. Larger A/R will perform in the opposite manner.

rwdxtacy 10-29-2012 06:22 PM

the Ca18 turbo is too small imo. If you are looking for a replacement pm me. I have a sr t25 from a blacktop i got off zilvia. I made 197whp with rx7 460s and ms1. pretty fun setup.. my turbo is in pretty good shape too. i can send you pics. Just PM me if you are interested.

bmseven 11-18-2012 12:23 PM

Thx for the replies, having removed the Turbo snapping a couple of studs on the way it is indeed a Garrett 2529 as fitted to Saab 9000 complete with the 5 bolt flange (fitted to 9000 275bhp B202F lump from abt Jan.1989 to Dec.1992)
I should point out this was a standard fitment on the BBR Turbos on the other side of the pond in the UK.
Unfortunately I think the exhaust/wastegate has seen better days as its full of cracks, I know its a Garrett and the cracks are standard just think with the snapped studs and cracks its a bit to far gone for my liking :)
Can anyone confirm or deny my reconditioned CHRA Cartridge for the above TB2529 will fit in the Nissan T2525 465795-3 as fitted to S13's?
THx the N00b! from across the pond

dustinb 11-18-2012 08:32 PM

I have no idea if that saab turbo will be the same as the nissan SR20/CA18 turbos. But for your timing, I would imagine you have to set your bass timing in megasquirt and then you use your ignition table to adjust your timing electronically. With my AEM EMS you had to go through a full timing calibration.

albumleaf 11-18-2012 09:15 PM

If you have megasquirt, you set the timing to whatever you set it in Tunerstudio as your offset.

bmseven 11-19-2012 02:27 AM

Oops my bad sorry guys :jerkit: should have said, we calibrated the timing as per DrewLGT's post below
is this the proper method for setting timing? - Miata Turbo Forum - It's the Cat's Meow

See been searching and reading lots :bowrofl:
Thx again
PS if anyone has a Nissan Turbo (as above) handy can they measure the core diameter on the exhaust side


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