Any experience with small trim (48) GT2871?
 

There are 3 trims, 48, 52, and 56.

I think most everyone's used the 52 (?).

The 48 trim compressor appears to fill the gap between the GT2860RS compressor and the 52 trim '2871 ...

I believe the 56 is generally considered the 'standard' trim for the 2871....that's what mine is.

the 48 doesn't really seem that common

Serious question: what is your fascination with small trim?

(Posting from my phone.)

Sounds like a shitty combo.

small housings + large wheels usually results in failaids. You don't get the lowend response or the topend flow that you "theoretically" should

I went with the .56 trim.

?? small trim is a different wheel, right, not just a different housing?

Also, I thought Sav had the middle size trim (52), not the big one.

I have a 52.

yes, trim describes the size of the wheel.....not the housing (that's A/R)

heres all the maps.... would be cool to see an overlay of all 3, but i haz no skillz

https://www.miataturbo.net/attachmen...ine=1316788716

https://www.miataturbo.net/attachmen...ine=1316788716

https://www.miataturbo.net/attachmen...ine=1316788716

You're right. My bad. Somehow thought this was about ar

Because street car.

I think your current powerband is perfect for a street car. If you fix the few issues it has it should get even more responsive and widen the powerband to the left a little as well.
Or consider the little twin scroll snail out of a MINI: full boost by 1800:giggle:

Anyways back on topic:D

Just like all of you other obsessive fools, I'm always thinking "what if I tweak this or that". Also, my thinking about the wee 2871 is not just for myself, but for other fools considering the 2871. :)

But yes, I'll see if I can get back my missing 200 RPM or so of spool. If I then go "ohmygod this is so much better", then I'll stick to my wee 2560. If I go "meh", then I'm a gonna be bigger turbo dreamin'.

street cars work best with big laggy turbos.

because hypermiler.

Hypermilers with small turbos can open the wastegate in cruise a la BMW 335i. :)

Depends on your definition of "street car" but Id have to agree (even though I'm not sure if you're sarcastic or not lol)
On my "street car" the only time I opened it up was on the freeway or a freeway onramp. I had plenty of lowend and response down low to not hate life and get decent mileage. When I wanted to haul ass it was just a downshift away.

In Jasons case though, (going off what he's posted in previous threads) he likes auto-x type driving, twisties, etc....So response and lowend grunt is thuper duper important to him, and I think I understand what he's going for here.

Do you have e85 there Jason? You're in the bay right? Cause with e85 you would not only get a little better spool, but be able to seriously push that little snail of yours to its limits.

I could open mine too BUT my wastegate port is teenie and probably not the most efficient passage for exhaust gas.

i just dont see the point of the 71mm wheel over the 60mm wheel when we talking about gaining only 5 more lb/min capacity and going from a short fat efficiency map to a thin tall one...meaning it's a better turbo for higher boost but lower flow rates.

You're comparing the 2860RS and the small-trim 2871?

(Posting from my phone.)

Yeah. 35 lb/min vs. 40



On a 60mm wheel vs. 71mm

I guess I don\'t see what the gain would be. The shorter fatter island of the 60mm lends itself to lower boost and higher flowrates. The 71mm is tall and skinny so its made for high boost levels but not a lot of flow considering.

The compressor map that garrett publishes for the 2871 is deceptive. At least for the 52 or 56 trim turbos, the compressor map is the same as what you get in a 3071r. It just looks thinner because garrett didn't fully flesh the map out.

Adding the GT2560 and GT2860RS. All maps arranged from smallest to largest.

GT2560:
https://www.miataturbo.net/attachmen...ine=1316881636

GT2860RS
https://www.miataturbo.net/attachmen...ine=1316881636

FWIW Garret has updated their website

Re:2871
There are 3 GT2871 compressor trims - (48, 52, 56), and 2 a/r's (0.64 and 0.86)

Garret's page now calls the 4 variants of GT2871, by a suffix: (1) (2) (3) and (4)
http://turbobygarrett.com/turbobygarrett/turbochargers

Only "(3)" uses the small 48 trim, and it has both sizes of exhaust a/r available. The small a/r is labeled
Turbo p/n 743347-3 chra p/n 446179-31
(Direct Link doesn't work, gotta go to above link and click "GT2871 (3)" in bottom right.

FWIW Here is an interesting post by my buddy with a 3071 who went driving with me and my 2560. He was shocked how much of an advantage the 2560 had powering out of tight corners, while the 3071 only having a big advantage above 80 mph or more:
http://forum.miata.net/vb/showthread.php?t=435110

I like to add these two since I'm in the market for new turbo for my built street car and can't decide between GT2871R (56 trim/ .64 or .84/2) and these,

GTX2867R

https://www.miataturbo.net/attachmen...ine=1323945180

GTX2863R

https://www.miataturbo.net/attachmen...ine=1323945180

2867 looks pretty sweet...now i hate my 2871, thanks lol

a smaller wheel that can produce the same power, is more efficient, and will spool faster.

I'd rock it.

The GTX2863 map appears to be similar to the small (48 trim) 2871 but is smaller (less inertia) and runs at higher RPM. May be a better speed match in spoolup so it gains a lot of spool without losing topend! Wait, it has even more headroom up top!

I plan to have the 2863 soon.
I am thinking the S6 mani from BEGI, either their intake mani or a custom.
Oh, and Tial vband .86 housing...
I may throw in some cams too. i am looking to keep all of my same power levels and just have a better powerband.

Oh, I may stroke the engine too.

The 2863 really looks like some quality cats ass stuff..

More fun with maps. Now with 1.9L engine airflow overlaid. Note that these assume 100% VE. So for stock cams, peak power is the airflow along the 6000 RPM line.
The reason they are for a 1.9L engine is because the dude who made them used 0*C standard air density instead of 20*C. The difference is about 6%. I'm assuming Garrett use 20*C.
So a 1.8L engine will require 7% less flow.

These were created by "mainstayinc" in this VWVORTEX thread:
http://forums.vwvortex.com/showthrea...what-you-think

GT2560:
https://www.miataturbo.net/attachmen...ine=1324314058

GT2860RS (disco potato):
https://www.miataturbo.net/attachmen...ine=1324314058

small (48) trim GT2871:
https://www.miataturbo.net/attachmen...ine=1324314058

GTX2863 comparo against 48 (small) trim GT2871, with, and without 1.8L RPM lines.

GTX2863 gets its topend from being able to rev to the moon. It doesn't choke as early with lots of flow, it just keeps revvin'.

Also in this comparo note the slowest speed line is 65k rpm instead of 59k rpm. Should give better spoolup.
https://www.miataturbo.net/attachmen...ine=1324316161

https://www.miataturbo.net/attachmen...ine=1324316161

Sucker will go to 22 psi and 42 lb/min, while the 48trim 2871 is only good for ~18 psi and 36 lb/min. Despite the quicker spool.

I just discovered this. A company called Forced Performance sell a machined billet 68 mm compressor wheel called an HTA 68 mm wheel. It's meant to be mated to a 2860RS compressor housing after some machining. The resulting turbo is called a GT2868 or an HTA2868. They sell both whole turbos, and the upgrade package.

Supposedly spools better than a 2860RS with a better topend (dunno if this is true).

Threads:
http://highboostforum.com/forum/show...on-HTA-wheels.
http://www.audizine.com/forum/showth...iAL-2868-Turbo)

Wheel:
https://www.miataturbo.net/attachmen...ine=1324592099

Dyno on a 1.8T (200 ft-lbs at 3400 RPM):
http://www.mnaudi.com/gallery2/d/787...ot-25psi-19psi

Spool demo on a 1.8T (pretty damn good, 15 psi at 3500 RPM in 3rd)

That 1.8t is a significantly better flowing engine than what we have though. I owned an AEG at one time.

Here you go ladies, GT2860RS vs GTX2863.
Bottom end nearly identical, GTX2863 topend extends waaaay up.

https://www.miataturbo.net/attachmen...1&d=1325800830

This is a great comparo thread! I think I'll be going with the gtx2867(also looking at the EFRs) for my power goals but random question for you guys that might know. What's up with these turbo's when they say max out put is, for example, 45lbs/min and they dyno and are putting down like 550? It's not usual but it happens, I've seen a few with e85, some with water/meth injection, some race gas and a few on straight pump gas. How does this happen if max outout is supposed to be 450 and they make more and sometimes signfigantly more?

It doesn't. People lie.

I mean I've seen the dyno sheets, you referring to a "corrected" dyno or just lying about the turbo/setup all together?

Edit: One prime example being "Eliminator" on his 50 trim...

http://forum.miata.net/vb/showthread...ght=eliminator

A turbo rated for 450 hp.....somehow managed to push over 600 whp

Another question, since I'm looking into the 2867. How signifigantly different would this turbo spool from the .64 A/R tial housing to the .86 A/R tial housing? Also, what could I expect as far as differences on the top end power?

Search. Lots and lots of discussion has happened on .64 vs .86. If you don't want to search, then buy the .86 housing like all of the cool kids do (hustler and me).

What would be the maximum safe boost on a gt2871? I'm about to order my turbo kit when my taxes show up and I've really been leaning towards the gt3071 but recently started lookin at the smaller one... I was think I could still get the same general horse power I want but it would be more responsive... Am I correct in thinking that? I'm shooting for about 325hp daily

325 then 2871 is plenty, no reason to get 3071.

max boost for 2871 around 22-24psi really. after that efficiency starts dropping off

Turns101 ran 28psi on 2871. I ran 30psi on my 3071. He had more power and held boost to redline because he had a tubular manifold. I had a log manifold.

And yes you will probably need to boost 24psi or so.

BTW I recommend a Borg S200SX. MUCH CHEAPER and as good.

Well, of course you can run more, but then you starting to overspin the turbo and get it out of its efficiency area... IMO if you're planning on running more than 22-24psi, then look for 3071 or something with a lil more compressor flow, so you can do it more efficiently.

2.5 PR = 22psi
2.75 PR = 25.7psi
Looking at it a lil closer then I'd say yeah...about 24psi max is what I would do.

If 325 is your power goal, 2871 can def get you there. Probably closer to 20psi with a typical setup.

http://i165.photobucket.com/albums/u...7/Miata/56.jpg

You may find the GT2860RS with the small housing will choke flow too much. The big housing is the way to go. You can make 16psi at 4500rpm on a log manifold with good tuning, that is about 255wtq on a mustang at 4500rpm. The compressor or cams will run out of steam above 6500rpm. Something runs out of steam up there, I'm not sure what.

The GT2860RS was made for the big housing, use it. I think it works very well on my car, which delivers power like no other turbo Miata I've driven, just don't expect more than 300whp on a Mustang.

First off, yes I know this thread is old as hell. However, this is the only thread i could find with people discussing the 48 trim gt2871 so for the sake of anyone else who decides to use a "legacy turbo" on their build i figured i would provide some actual feedback. I picked up a very lightly used 48 trim gt2871r off some guy on craigslist for pretty cheap so figured I would give it a try. The turbo I was running before was a gt2560. I bought the 2560 new from Nissan (S15 spec r turbo). So far I have been very happy with the 48 trim 2871. It spools extremely well.

I datalogged a pull from 2k RPM in 5th gear tonight (6 speed 3.9 rear) and I made my set wastegate pressure (15psi currently) at 3350 RPM. This is on a built 99 motor running 83.5 mm supertech 8.6:1 pistons, a taco taco manifold, Artech 2.5 divorced wastegate downpipe to 2.5 inch exhaust with no cat.

Transient response feels great too and i can tell no significant difference between how the turbo spools up compared to my 2560. However, after spool up this turbo just pulls so much harder than the 2560 did. Keep in mind this all seat of the pants data aside from the spool data which was datalogged. I can post the log if needed

Anyway, if anyone else comes across a great deal on a gt2781r 48 trim turbo and they are curious for some actual feedback based on use, I'm extremely happy with how its performing so far and it does not exhibit any feelings of slower response compared to my 2560.

I ran a 48 trim 2871 churbo on my compound 1.6 with good results. It runs out of gas up top pretty quickly though.

Alright here are some results to go along with my initial impressions/thoughts. Still very please with its performance, spool isn't far off of my GT2560R. In colder weather it will make 17 lbs at 3450RPM. Full list of supporting mods in the dyno and timesheet section (https://www.miataturbo.net/dynos-tim...5/)

https://cimg6.ibsrv.net/gimg/www.mia...8b099ffb47.jpg