K26/GT2871 R good for RS2

[kalsket]

Why anyone should? It has same compressor as 2871 with larger hot side. There is no backpressure problem with 2871 so why take bigger turbine?

[DamoM]

Why anyone should? It has same compressor as 2871 with larger hot side. There is no backpressure problem with 2871 so why take bigger turbine?

well I guess the fact that is has a bigger turbine means that it has better characteristics at higher revs, hence why they say that it is good for 500 bhp applications? I have ione on my 10v UR quattro and you get full boost by 3000 rpm and superb flow at higher revs.

Depends what you are after I suppose; quicker spool up than an RS2 turbo and (in reality as I believe certain claims are a little optimistic) potential for up to 400 bhp or same spool as an RS2 turbo with potential for 50 bhp more?....different strokes for different folks......

[Erikb]

But the reason I would go for the 2871 is that it already produces over 450 hp. Look at the thread pekka 400+. He has this turbo and it produces 458 hp.

[DamoM]

But the reason I would go for the 2871 is that it already produces over 450 hp. Look at the thread pekka 400+. He has this turbo and it produces 458 hp.

I am eating my words.....!

[kalsket]

Erikb, I have that turbo and 450+ mentioned in that topic, Pekkas ex-car has GT2540R and about 430Hp.

[Erikb]

Kalsket, can you tell me what the difference is between the GT2540R and the GT2871R. Which one would you recommend?

[maRS2]

What would be the maximum output of a GT 28 RS on RS2
Surge problem?

[Erikb]

I dont exactly know, maybe the rs2 EM, rs IC and exhaust will be a bottleneck.

I bought a 600 x 300 x 76 intercooler and will go for a turbular IM, for exhaust I go for a 3" with a separate wastgate pipe.

[kalsket]

With GT28RS I would expect 350-400 Hp depending on other hardware. Because it has smaller compressor I think it wouldn't have surge problem or at least it would be smaller.

Choosing from 2540/2871 I would take 2871 because 2540 is getting of production if it already hasn't. About their difference I can't say anything more than you can read yourself on atpturbos website.

[maRS2]

Kalsket do you think it's possible to have with a GT28RS
2 bar at 2500 rpm and around 380 Hp
on a RS2 with full 3" stainless exhaust ( very straight)

When do you get full boost on your GT2871 setup

[kalsket]

at the moment I get full boost around 2800

(I guess GT28RS might do those figures just fine, rpm for full boost might be bit higher than that.)

Edit: Checked the compressor map for GT28RS. It will give you max 2 bar and only around 4000 rpm, and with bad efficiency. Here are figures I calculated for that turbo with very well flowing head.

rpm / bar / Hp / Nm
7500 0,9 365 342
7000 1,1 374 375
6500 1,1 371 400
6000 1,3 372 436
5500 1,5 373 476
5000 1,55 353 495
4500 1,55 324 505
4000 1,55 288 505
3500 1,2 219 440
3000 1,2 188 440
2500 1 132 371
2000 0,3 67 237

[maRS2]

Looking your number I think my RS2 Turbon is better
I have 2,1 bar at 3000 rpm

[kalsket]

You could be right. At least it is better for the fact that you already have it

Just one hint for the future. Boost pressure means just about nothing when comparing two turbos of different size. Air mass is the only thing that counts when you want power. In other words: you can get the same air mass what you get with original turbo with 2,1bar with another turbo with 1,0 or 1,5bar. Therefore in this case look only at the Hp and Nm figures. (RS2 turbo can still be better.)

Edit: AFAIK: Anything that RS2 orig. turbo gives above 1,8bar is made with quite bad efficiency = More heat, less air mass.

[Jamo]

*bump* maRS2 what turbo did you go for in the end?

[S4turbo]

Kalsket, how did you retime the cams, what hardware do you have? Can they be retimed individually?

Possibly that may be necessary. Repo is referring to my engine which had surging problem when running AAN ex-cam with ADU cam belt-gear and ADU in-cam.

Due to surge boost had to kept in 1.4 bar 3-4,5 krpm. After retiming of cams 1.9bar without any problem.