I5 GT Turbos 2871 / 3071 / 3076 / 3082 / 3582

[Jon441cc]

Am i right in thinking that Garrett bb CHRA has to be replaced if failure occurs and can not be rebuilt ?

Is this the case with all ball bearing turbo's

[A80Avant]

yup,pretty much

[gedu]

With Garrett, whole chra needs replacing. Turbonetics and Compturbo can be serviced without replacing whole chra.

[denniselbows]

which would be the equivalent turbonetics turbo to the GT2871R/3071 and how do they match up. has anybody fitted a turbonetics turbo to their s2

[A80Avant]

a friend had used a customade turbonetics once and had made 358whp.Negatives was a poor communication with turbonetics and a long wait to have the turbo delivered.Eventualy due to a a boost leak and wastegate problems,he managed to eat the turbo up due to high boost .

[Henkjan]

how about the GT28RS? the ultra fast spoolup appeals to me... but...
I heard some stories that it might surge...
Q1: is that true?
Q2: if yes, when is there a risk?
Q3: why does 034 sell it in it's I5 kit?
Q4: does this apply to both the .82AR and the .63AR?

Q5: can someone please define what exactly is the phenomena that everyone calls surge? is it the same that occurs with industrial gas compressors

Surge - is the point at which the compressor cannot add enough energy to overcome the system resistance. This causes a rapid flow reversal (i.e. surge). As a result, high vibration, temperature increases, and rapid changes in axial thrust can occur.

and for which all compressors I have seen have a control valve with a return from pressure side to suction side to keep the compressor in its stable operating range

[S2central.net]

which would be the equivalent turbonetics turbo to the GT2871R/3071 and how do they match up. has anybody fitted a turbonetics turbo to their s2

If you can find old threads started by Mark Halligan - I'm pretty sure he had something from Turbonetics when he began the monster tuning bug on this place some years back. Pretty sure that was in 400bhp territory when 1st mapped by Mihnea before MRC got off the ground. It was pretty tractable low down and mid range too - I was out in it a few times - great car and superbly put together by Mark with his very high standards. Stock cams and bottom end I think, but he did more work after that.

It was some weird hybrid turbo - I'm going out on a limb here with my wobbly memory of a KKK#8 hotside of some sort that matched up to SQ EM and it was a T04e compressor - and maybe a roller centre not 100% on that.

That thing made the most glorious noise on full chat - its what got me into scream pipes - the noise of that thing honking between the roundabouts in MK near my house just made the hair stand up on your neck.

I also recall that he upgraded from that spec - as it was early days - he was a pioneer really - I was just starting to get my head round compressor maps in those days and he was fluent in them by that time.

[repo]

Surge is exactly that.

It is a pressure too high for present flow. On compressor map the line on the left side of the efficiency islands. The smaller the turbo, more upright the surgeline. This is why large turbos tend to surge at midrange.

Disco potato is pretty equal to RS2 K24 in flow caracteristics. Won't surge in I5. Never tried, but seriously doubt it will. Or then You have 2 bar at 2000rpm.

Surge is severe shock to turbo impeller and bearings. So yes, it is risky.

I hope no one does such a bad custom turbo as the 2871 is.

[Prophet_dlx]

so repo you would rather go for the GT28RS than for a gt2871, has it been done yet, does anybody drive a GT28RS setup??

[S2central.net]

@Repo - contraversial...

Why you not like the 2871R ?

My experience is limited to one car on stock cams... If I had kept the boost profile to the right of the surge line we would have had some lag - but I was able to dial in more boost than the surge line showed on paper and it spooled up a treat without any surging in normal driving. It was explained to me that these surge lines are very conservative - maybe not true on all Garrett compressor maps, but I was a bit surprised by how aggressively it boosted for good (not killer) mid range torque without surging. The only way we could get some surge was low-mid revs with full throttle and heavy left foot braking to artificially load it up for higher boost than what you get on a normal WOT run.

I'm not saying that 2871R is perfect choice for ~400bhp here but I just didn't get all this nasty surge that is so often associated with the roller bearing turbos.

[S2central.net]

GT28RS disco potato has an internal wastegate does it not ?

Or is there now a variant with external WG ?

[bimmerboy]

The gt2871 does just fine on these engines

[repo]

I don't like the idea of 500hp compressor and 400hp turbine combined.

If You use 70% of 2871 capacity, it might be ok, but I always want to push max out, to get best powerband.

Main issues with 2871 are boost control issues, easy surge, high backpressure and high egt due to that. If You drive with 1,5 bar, boost control is not that bad, but over 1.5, it is very difficult to handle.

I also dislike the possibility of not being able to repair the turbo, which makes it disposal.

[Rusty]

What other options are there that are comparable to the 2871? Bolt on, faster spool than RS2 and 400bhp capability? (Other than RS2 turbo)

[repo]

CT and Netics have KKK replacement turbos, that can outperform the 2871.