Turbo advice needed. GT2871 or GT3071

R

radiobar

New Member
hi !

as i need a new turbo i decided to get one of this:

GT3071r
comp. 56 trim 0.50 A/R
turb. 84 trim 0.64 A/R

or

GT2871r
comp. 56 trim 0.60 A/R
turb. 76 trim 0.86 A/R


which one would be a better choice for around 420hp and good response.
what about the gt2876r ?

actually i got the GT3071 with 90 trim and 0.86A/R - but its to laggy
so will the 0.64 housing with 84 trim be a better option ?

thanks
 
A

ashills

Active Member
get the 3071 with .86 exhaust as the .64 has to much surge issues
the 2871 wont do 400 let allown 420
 
R

radiobar

New Member
hi !

actually i got 0.86 installed(90 trim),but as i said its to laggy for me.
there is also a smaller trim avaiable(with .86),but only with external
wastegate. and i need an internal one.
 
Adam L

Adam L

New Member
Also, if you downsize to the .64, you'd be running a more restricted exhaust housing than the standard T28...
 
campbellju

campbellju

Moderators
Staff member
IMO, rebuild your 3071 as at least half of it still works okay and as Allen says you will struggle to make 400hp on a 2871.

Surge is a problem with .64, the .86 has less response so less surge. The .86 is less restricive so will probably make more power at the top end. If you think the .86 a/r is laggy then you've answered your own question.

To reduce surge on the .64, port the wg and loacate your pressure sensor before the FMIC.
 
Trip

Trip

New Member
I did the same homework myself around a month ago. If you do a search you will find my post somewhere. It was a photo finish between the 64 and 86 but according to my findouts, lag would be a couple of hundred rpm between the two. I ended up closing down for a GT3071R WG 0.86AR for best overall turbo.
 
R

radiobar

New Member
hi !

i was told thats its not possible to rebuild it.
because there is nobody who can balance a ballbearing turbo.
is that correct ?

thanks
 
Fusion Ed

Fusion Ed

Active Member
Yes that is correct. You will need a new core. If your housings are ok then you can keep them, and may save a few hundred over a new turbo (r/r cores are about £600ish)
 
Adam L

Adam L

New Member
radiobar said:
hi !

i was told thats its not possible to rebuild it.
because there is nobody who can balance a ballbearing turbo.
is that correct ?

thanks
Click to expand...
Reason being is, Garrett don't release rebuild kits for rollerbearing turbo's, along with their VNT turbo's. it's a new core you'll need. As Ed entioned, £600 roughly...
 
R

radiobar

New Member
hi !

i dont know.
my plan was to change the exhaust housing,because
turbo was very laggy. full boost around 4500-5000 rpm
it was installed for around 20000 km.
after removing it i found it.
 
K

Keira

New Member
from seeing the state of your engine over the last few days i'd put any problems with 'lag' that you've been experiencing down to something other than the turbo.

either sized turbine housing on 3071 on a properly set up car cant possibly be described as laggy at all. all the ones that i've been in set up by ed have gone very well. Personally i think you either need to give up tuning yourself if its you doing it or find another tuner tbh.

the crack in the housing probably hasn't been helping matters either but i wouldn't expect to see that on a new turbo in a healthy running car.

didn't you originally get it mapped by that idiot at innovate ?
 
Last edited:
R

radiobar

New Member
hi !

first it was mapped by innovate.
he came down here to germany and mapped 3 cars.

but i was very very unhappy(the other cars too)
i made a 13.2 - same as my old engine with standard turbo.
and my gt3071 was running with 1.7 bar.

later i found somebody here in germany and he is very good.
after mapping i thought i got a new car.
the only problem was the very late boost.
but car was fine for over 8 months.
few weeks ago we tried adjustable cam pulleys and think
something got wrong then and i melted one piston.

the damage to my turbo happened long before i think.
maybe when car was mapped by innovate.(we got
around 1100 EGT max on highway - but only once for
a short time)
then i always got an eye on EGT and there were no problems.
max. 900-950

its all very strange.
and i need a full rebuild now

maybe i will go for 2.2 big bore and the same turbo.
with 2.2 it should spool better than with 2.0
or i go for the 2871r
 
S

str_motorsport

Guest
Mate it seems to me like rea bad mapping o your engine...
with such high EGT pistons will melt..you were running lean.
the gt30 should spool a lot faster .
I also think that the cam timing was wrong...you can't fit jun 272 using the same cam timing as a std cam...
Also i really don't like the t2 turbine housings....really too small,high back pressure ...
you should go for the gt30 turbo...fast spool and less boost to make power..less boost also means less heat and detonation.
Talk to your engine builder and to the mapper...
 
S

str_motorsport

Guest
your housing looks badly cracked...it is quite normal to crack for an internal wastegated turbo....get an external gate version
i personally prefer a little more lag and less boost.
but note that your spoo up was really too late for this turbo....
people are getting full boost below 5000 rpm on the gt35r!!!!!
 
Fusion Ed

Fusion Ed

Active Member
The turbo was damaged by your recent meltdown. I guarantee it. I saw the exact same in a 200sx I was just asked to do an engine swap on. The old engine had similar internal damage to yours, and exactly the same turbo damage.

1100egt will not necessarily cause instant damage. It depends too on the ignition timing and what load the engine is under when this is happening, under full load yes, but its not likely, unless your running far too lean. EGT although useful with other instrumentation alone can not tell you enough about a particular condition. Indeed if for example you have retarded ignition timing EGT will be high, and cylinder temps not so. You risk more chance burning valves not melting pistons.
 
R

radiobar

New Member
hi !

i was told to run the 272 cams with standard 20 degrees.
whats wrong about it ?

i think that my second map is ok(done by the new mapper)
,because car was running good for around 8 months.
except my boost problem.
i have done several high speed runs on highway here.
here i was hunting the new audi S8(450hp,V10) for around 15 minutes

http://www.weidewaren.de/tacho.jpg

if the map was wrong my engine would not last so long.


2 days before the damage we have tried adjustable
cams pulleys and i think that was the reason.
but EGT,knock and AFR were all ok.

and if the turbo was melted same time as my piston
i still dont know the reason for my late boost problem.
but people say that my melted turbo caused the boost problem.

so its all very strange.
i think i will never find out.

depending on the costs i will get the 2.2 big bore and same turbo
as before or i will go for 87 pistons with a gt2871r

2.2 should give me more response on same turbo as 2.0.
 
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