Why not a SR20 T28?
 

1) Why aren't SR20 journal bearing T28 used more often than the SR20 T25?

It seems that the two spool similarly and a T28 wouldn't run out of steam by 6000 rpm, unlike the T25.

I already purchased a BEGi T25 exhaust manifold, and from what I understand, the SR20 T28 works w/ it as well.

2) Would the Begi-S DP work with a T28, with no modifications?

Thanks Sam for the info you gave me.

my sr20 is a t28 i believe. (the one i use)

T28 is just the larger A/R on the turbine correct?

i thought so, i have a .80 AR as opposed to the .46AR that comes on some of the SR20

the flanges for the intake and charge pipe on the T28 are clocked at different angles... but unless you are using the stock sr20 elbows this shouldnt matter. if you are, buy addapter flanges or make your own..thats wat i did on my 240

I think the T28s are a bit more rare, and expensive...right?

i believe so, i think the 28 had a .80 AR like my 2 and the t25 had a .46

my t25 had a .80 iirc, they came in two sizes.

the t25's come in a few different sizes, depending on whether it was on a gtir (sentra)... redtop SR or a few later blacktops

the t28 also came in different sizes depending on s14 or s15... only the s15 is fully ball bearing

And yes..they are more expensive

From wiki.
The second generation in the S14 Silvia produced 220 PS (166 kW) through the use of Nissan's VTC variable valve timing and a ball bearing turbocharger. The final S15 Silvia version produced 250 PS (187 kW) @6400 rpm and 275 nm @4800 rpm with an improved Inconel impeller wheel for its turbocharger.

I picked up my T28 BB for $201 shipped off ebay.

That's a helluva deal.

There's also FWD T25's and T28's. Bluebirds & Avenier's had the T25 (a small number of them are ball bearing), GTiR's had the T28, all are journal bearing.

C

AHHHHHHH.

Tom the turbo you have is a t25.

t28 + t3 = t28

all t25s have a 50mm exducer, all t28s have a 60mm exducer...the rest is exactly the same.

the only difference between them is the compressor wheel, a T28 will have the exact compressor wheel I have, a T3 super 60 wheel. 47mm inducer / 60mm exducer.



the t28s are harder to find.....the end.


some t28s come off GTRs and have an odd turbine outlet which requires a different flange.

only JDM t28s have BBs and most likey have said odd shaped turbine outlet flange.

The T25 I have sitting on my desk has a .64 A/R on the turbine.

scott send me your t3, i'll turn it to a t28 than..

I have a spare 50 trim t3 wheel....you still gotta machine the housing :)

the wheel itself is about 10mm taller, which would also have to get milled off so it could fit on your shaft. :)

http://boostedmiata.com/random/t3_vs_t25_wheel.jpg

tom, here's your wheel vs. my t3 wheel.

just let me think, i may do it... i know you were thinking bout doing it while you were taking my turbo apart looking to see if they're compatible.

yep. i wanted to see for myself what it would take. it's a common upgrade, technically it's all a t28 is.

even now. a gt2860 is a 47mm inducer and 60mm exducer, the same size wheel as mine. my advantage however is the larger turbine.

Like people have said they aren't used as often because they are rarer and more expensive.

The sr20 t25's are a dime a dozen.

Of the journal bearing t28's the one off of the gti-r seems to be the one to have.

here are some more info on my T28 turbo.
First the ebay link
http://cgi.ebay.com/ebaymotors/ws/eB...MEWN:IT&ih=001

Some close ups.
http://www.jobambo.com/turbo/t1.jpg
http://www.jobambo.com/turbo/t2.jpg
http://www.jobambo.com/turbo/t3.jpg

Part number reads
14411-69F00
466541-1

According to http://www.turbobygarrett.com/turbob...R_466541_1.htm
I believe this is a GT2560R Turbo. For the first time, luck might be on my side.
BTW today is my Bday, if this is a gt2560r i could not be any happier.

Most of the SR T25 turbos I see are like Jobambo's, where the compressor inlet has a 2 bolt diamond shape. However, I've also seen some SR T25 that are round like this. What's the difference (other than shape)?

Attachment 214987

they didnt come from a sr20... its possible that those are from an RB or anouther nissan tho

Seems like you got a T28, it looks the same as the one I used to have anyway:

http://farm1.static.flickr.com/63/22...0c1aca2811.jpg

More pics here:
http://www.flickr.com/photos/saboteur/tags/turbo/

So what the kinda T25 do I have sitting on my desk. .80A/R on the compressor and .64 A/R on the exhaust. Its like nothing mentioned in this thread.

How did you deduce that? Is it from the round compressor inlet (just so I know what to look for next time)?

How about FWD SR20 T25? Do they look the same as RWD T25s?

www.nicoclub.com .... GREAT nissan forums. there is alot of info spread throughout there about the differences including pictures and discriptions

It's probably what I know as a t25g, when you look at it side on the comp housing is wider. Im pretty sure thats what is on the s13.

Yep, you are right its a T25G. Thanks for the insight.

Its like a GT2554 by those specs. Good to know.

Sam i've got the same turbo. What type of power are you expecting?

My initial goals will be 180 - 200. I dont plan on going further and I think this turbo will give me just that easily.

The only way you'll be able to see a difference is the compressor wheel:



since the compressor in the t25 is smaller, you can see the large "lip" http://boostedmiata.com/lars_t25/larst25008.jpg(1/2") on the housing. a t28 will have a very small lip if any.

otherwise they look identical, aside from part numbers.

There seems to be some confusion regarding the garrett turbos that came factory on Nissan cars here. This is the info I have gathered from being in the SR20 scene for 9 years now. I've owned/driven a turbo B13 SE-R for 7 years so I know a little bit about the stuff. :)

FWD:

journal bearing t25 (most) Good for 250whp (2.0L) .64 exhaust housing
ball bearing t25 (later ones, rare) Good for 250whp (2.0L) .64 exhaust housing.

The fwd t25s have the same specs as the rwd turbos however there are a couple of differences. The compressor inlet is not a 2 bolt flange, it uses a coupler connection. The compressor outlet is the same 3 bolt pattern but clocked differently. They turbo on a fwd car is flipped around compared to the rwd but it can be easily re-clocked.

journal bearing t28 (GTi-R, sort of rare) .86 turbine housing. T3 compressor housing with 60mm wheel. Good for 300whp+ (on a 2.0L) A good upgrade is to swap on a T04b housing from the rwd t28 (you need the backing plate too).

RWD:

S13 t25s (all journal bearing afaik) good for 250whp. .64 exhaust housing.

S14 t28s. (All ball bearing) Have the same .64 turbine housing as t25s. They have a t04b compressor housing with the same 60mm T3 wheel as the GTi-R t28. Some may have the cast in divider on the turbine housing. Good for 280whp+ (2.0L)

S15 t28s (All ball bearing) Have the same .64 turbine housing as t25s. They have a t04b compressor housing with the same 60mm T3 wheel as the GTi-R t28. They also have an inconel turbine. This turbo is sold in the aftermarket as the GT28R. All have the cast in divider on the turbine housing. Good for 280whp+ (2.0L)

There are other t2x variants from Skylines and 300ZXs but I'm not familiar enough with the specs to comment on them.

Very good little write up there, that is quite accurate. The only thing missing is spool characteristics, boost threshold and the compressor maps (which are hard to come by).

The OP's goals are 180-200 and a T25 would easily give that and be better able to hold the power curve a bit higher than the typical SR do to the 1.6-1.8L displacement of the miatas. The t25's are cheaper and MUCH more plentiful; the also don't have any widespread issues or problems with them and should last quite a while if run < 1 Bar.