These are specs of the common SR20 turbo:
Compressor: T-25, 60 trim 56mm BCI-1 compressor.
Turbine: T-25, 62 trim 53.8mm 0.64 A/R turbine housing.
Center Section: Journal bearings

These are specs of the S14 turbo that has the larger wheel:
Compressor: T-28, 60 trim 60 mm BCI-1 compressor in T-04B housing
Turbine: T-25, 62 trim 53.8mm 0.64 A/R turbine housing.
Center Section: Ball Bearing

Same turbine/ wheel size. Larger compressor/ wheel.

Specs on the GT2554 from the garrett website:
Compressor: 54.30mm 60 trim wheel
Turbine: 53.00mm
Center Section: Ball Bearing

Specs on the GT2560 turbo from the garrett website:
Compressor: 60.10mm 60 trim wheel
Turbine: 53.00mm
Center Section: Ball Bearing

It appears that the SR20 turbo is actually a bit larger than a gt2554. It also looks like garrett uses the same turbine/ wheel for the 2560 and 2554, just different compressors/ wheels. Makes sense to me. Larger compressor wheel means larger volume of air will be displaced.

For that same money you could get a s14 T28 which is single ball bearing ...

EDIT... 3rd gen covered it

I have been looking for an s14 t28 forever. Let me know if you find one. I want it.

Todd, do you ever look at Zilvia.net for a s14 t28? They pop up all the time there.

Ray

Really? I didn't see any while I was looking for my t25, but then again it didn't take long before I bought one. How much do you see them going for?

Adam, I think the last time I checked there was one for $400, but if I remember correctly he said it could probably use a rebuild. I don't know if there are any currently for sale but that would be the first place I would look for one.

Ray

I had one. Sold it with my SR when I parted out my 240. Regret it a lot. They are somewhat hard to come by.

Is this what you're looking for, Todd? CT S14 T28 ball bearing. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Ray

Yes and no...I'm looking for "selling my blown s14 turbo. The chra is seized, but the compressor/ wheel is good....$50"
Let me know when that gets found.

do you just want a compressor wheel? I have a 50 trim t3 wheel and compressor housing you can duct tape to your chra...that'll make it a t28.

https://www.miataturbo.net/attachmen...ine=1346415477

Lol @ duct tape...pm me brainy, if serious.

if i can find it :)

For anyone looking for a cheap T25/T28, I was around 240's before miatas. This one works great and is probably the CHEAPEST you will find anywhere that isn't from ebay.

*ISIS T25/T28 Replacement Turbo - Nissan SR20DET - Enjuku Racing Parts, LLC

If you want a 2871 sized turbo the same company makes this turbo as well.

http://www.enjukuracing.com/products...n-SR20DET.html

Final edit? - I think these (both links) are journal bearing not ball bearing, fwiw.

A quick google search reveals that these turbos are actually really good units. The warranty on them is rock solid as well.