JasonC SBB

Anyone have one?

Savington

iTrader: (31)

.64 disco potato = ugly duckling. Worse response than a 2560R, no significant additional power capability, no reason to exist.

JasonC SBB

Is that opinion from dyno tuning?

Hmm, Stephanie is saying its got similar spoolup and power than the 2560 too.

Strange that the compressor and turbine maps say otherwise - at least 10% more peak power at 15 psi, and more turbine flow... I wonder what's up.

Savington

iTrader: (31)

It's the turbine. You can't flow anything past ~275-280whp through a .64 T25 turbine housing. Look at BEGi's early attempts with the .64a/r 2860RS on the S4 (?) manifold - the power numbers were pathetic.

I'd never recommend a .64 2860RS to anyone. Hell, I don't even recommend the .86 2860RS - the 2871R's compressor is so much more versatile and the response difference is negligible.

2560R for <250whp or stock motor
2871R for >250whp or built motor

codrus

Where do the 2876 and 3071s go here?

--Ian

hustler

iTrader: (6)

Post a log in 5th gear that shows target boost threshold and I'll show you mine 200-500rpm lower. Do it or I'll **** you up.

hustler

iTrader: (6)

9psi TTB ******ry pull on a dynojet:

Savington

iTrader: (31)

2876R is an oddball. Massive compressor wheel so it will respond a little slower, but you can't flow 500whp through a T25 turbine so it's not really a good match. Garrett themselves admit this, and it's not a common turbo.

3071R is basically the same turbo as a 2871R, just not as good IMO. The compressor wheels are nearly identical (they ARE identical if you have a 56-trim 2871R), and the turbine uses a slightly larger wheel with the smaller A/R. The larger wheel means less response (high wheel inertia) and you won't make more power than a 2871R since you have a smaller turbine.

The original 3071R had a 60mm turbine with a .63a/r turbine housing, which is basically identical to the 2871R (except with a much larger turbine wheel, which doesn't help transient response).

The 2871R .86a/r is a pretty bitchin' turbo.

Info below for reference:
2871R 52-trim:
Comp: 51.2ind,71.0exd
Turb: 53.9mm, 76trim, .86a/r, 21lb/min peak turbine flow

2876R:
comp: 52.8ind, 76.1exd
turb: 53.9mm, 76trim, .86a/r 21lb/min PTB

3071R 56-trim (T25 turbine)
comp: 53.1ind,71.0exd
turb: 56.5mm, 84trim, .64a/r, 19lb/min ptb

3071R 56-trim (T3 turbine)
comp: 53.1ind, 71.0exd
turb: 60.0mm, 84trim, .63a/r, 20.5lb/min ptb

3076R:
comp: 57.0ind, 76.2exd
turb: 60mm, 84trim, .63a/r, 20.5lb/min ptb

hustler

iTrader: (6)

Someone with photoshop skills should overlay the two compressor tables.

shuiend

iTrader: (24)

That is my 2871 at 9.5 psi on a dyno dynamics just for comparison. This was also not really tuned yet. I could prob run another 3-5 degrees of spark advance above what I was at that point.

VitaminD

iTrader: (14)

Savington,
You have an absurdflow setup and VVT.
What about us folks with a log manifold and a 95 head?
What if the ultimate goal is never over 250~280whp?
I am in the process of choosing a turbo now for my track only car and had the 2560, 2860, and 2871 in mind. I am leaning towards the 2860 because the 2560 would be working harder, and the 2871 seemed like overkill for my goals.

hustler

iTrader: (6)

Decide if you want to run it in the prime flow area or run it just south like I am. I'd probably do the 2560 but haven't put much thought to it.

It surprises me to see how close the 2860rs and 2871 are. I think my turbo on a proper dyno would show a more favorable low rpm output, but not by much. I also have no desire to run more than 280whp at all and these days I'm perfectly happy with 240whp on a Mustang.

VanMSM

Here's a 2860RS on a ETD long tube manifold with T3 0.48A/R turbine running at 13psi on my MSM.

shuiend

iTrader: (24)

I would highly suggest going with the 2560. You should be able to get 250-280hp out of it around 16-20psi.

I believe Hustler disliked his 2860 on his old Begi log manifold. I do know his spool was a shitton faster when he upgraded to the absurdflow manifold.

VitaminD

iTrader: (14)

Whp correct? What about heat? I know of a few guys with FM kits running the 2560 that are dealing with cooling issues on the track.

hustler

iTrader: (6)

I was pretty happy with what I had. However after going to the tubular manifold, it will be a cold day in hell (which doesn't exist) before I ever own another cast-iron, log manifold for a track car.

Savington

iTrader: (31)

You can probably max out a 2860RS on a log mani/95 head at ~18psi and you might get like 270-275whp. Maybe. Or you can run a 2871R and you'll need 16-17psi to get the same thing.

In the end, you're going to be disappointed with the spool no matter what, because you have a log manifold and a '95 head. I think Trey said he ****** his torque curve back 800rpm switching from a BEGi cast manifold (which is already better than a log manifold) to an AF shortram.

Turbo cars running hot on track is normal for everyone who doesn't own a Trackspeed radiator. :P I struggled with CLT issues until we started developing ours, and now I can do a 20 minute session at 350whp at Willow in 100*F heat without any temp issues, pull into the pits at the end, and then realize that I accidentally left the cooling fan off for the entire session, lol.

VitaminD

iTrader: (14)

Maybe a 2560 is the answer then with my setup if I can reach the 250whp goal with my current manifold/DP. My problem in searching was finding a middle of the road number, most threads I found quoted upper limits like you did above, which I'm not particularly interested in.

To get more on track with the OP and stop totally threadjacking.

I have read several post about the .64 a/r on the 2860 limiting ultimate HP but what about this at a modest power goal?

JasonC SBB

Here's the strange bit. Garrett's marketing shows that the 0.64 potato hotside flows about 15% more than the '2560 *and* has higher efficiency to boot. The former would suggest 15% more peak power capability, the latter suggests better spoolup for a given peak power.

'2560 , tops out at 14.5 lb/min:


Small a/r potato (lower line), tops out at 17 lb/min:

JasonC SBB

VitaminD, *if* your goal is 250 hp, you will be happy with the '2560 on the street and tight mountain roads. Don't understimate the value of response. My buddy with a 3071 chased me through some tight twisties with me and my 2560. On tight corner exits he said my car would leap ahead and he wouldn't be able to catch up because the straights were short. We both have 6 speeds and 3.9 rears, and were both using 3rd gear. 2nd gear would have been too short for him and the upshift would cost him time.

The 2560 is the perfect match for the stock motor because the latter can't take advantage of the higher boost the bigger turbos shine at. For an all-street car I would argue the 2554 is even better, giving up about 15-20 hp up top (maybe even less than that on an NA head) but generates oodles more torque and response at the bottom which is nice on a street car.