New Garrett Gtx2860R / 2863R / 2867R

[mr skidz]

I have run RSs to 28psi on a 3.0 with factory pipe work ( except ARC cooler, Z32 AFMs and modded TT pipe ) with no issue, holds boost @28psi perfectly to shut off, but power starts to fall over from around 7k through to the 8500 redline, which I have put down to the exhaust wheel/housing

but the 3.0 moves alot more gases @8k then a 2.8 which obviously moves more then a 2.6

Which brings me to my next point, what is the restriction, the T28 wheel or the 0.64 housing ?

If it is indeed the wheel then the larger housing won't do a great deal of anything to help power or response

what diameter exhaust did you have 3.5 or 4?

[Piggaz]

Twin 3 inch into a single 4 inch.

[XKLABA]

What he said with twin 5" bodied 100 cell cats

[mr skidz]

That's big , what power were you seeing at 7k as it started falling over

[Piggaz]

For the sake of adding more to this turbine/hot side discussion, I'll throw Gav's RS VS -5 back to back up. Those RS 71.1'mm wheels are so much bigger than the little -5's yet only gave 20 HP more.

[mr skidz]

Yes because they are a front to rear ratio mismatch they are overwhelming the turbine at every Revolution they are a bad turbo there needs to be balance like the dash 5 that doesn't mean you can't go 1 or 2 mill 3 mill bigger on the front wheel those r s turbos ah 11 mill too big in the front I know these turbos very well as I had 1 on my 180 and tuned it too its Max I know what issues they have

Edited October 9, 2015 by mr skidz

[Piggaz]

Who cares how big they are. How much air is the wheels moving. The 63 mm GTX moves the same amount of air as the 71.1 GT wheel (both 44 lb/minute). 44 mm/min is that volume of air regardless is its 1 mm or 200 mm wheel.

So, you're back to square one just in another form.

[mr skidz]

Except you don't have 71.1 millimetres of heavier compressor wheel to spin it's not easy for a small turbine wheel to spin a large cast compressor wheel that's 1 of the problems.

the Gt x 63 is a better diameter in a lighter weight so that problem has been fixed but yes flow is definitely there

Edited October 9, 2015 by mr skidz

[XKLABA]

I don't have the 28psi graph with boost on it

http://www.sau.com.au/forums/topic/104332-rb30-hybrid-upgrade-all-dyno-results/page-8#

I do have 24 psi in the RB30 dyno thread

[XKLABA]

It's also a matter of leverage to a certain degree and getting a 53.8mm wheel it push 28psi off a 71.1mm wheel is harder then off a 63mm wheel

[bigmikespec]

Didn't bigmikespec say the same thing as Mick_o did about the turbine wheels, either at the start of this thread or piggaz build thread and get shut down?

Yes I did say it, despite the aggressiveness I agree with Mick_o

People hate facts

[mr skidz]

Your afr's are beautifully plotted out against your power curve.

Who tuned that if you don't mind me asking?

Because not many tuners bother to get tunes that clean afr's always stray a little bit from what I see that's why I hate dyno sheets not showing the AFR plots. If afr's and ign are spot on then so will your power and torque curve I'm more interested in afr's then Power and torque figures anyway.

Healthier motors last.

Edited October 9, 2015 by mr skidz

[mr skidz]

It's also a matter of leverage to a certain degree and getting a 53.8mm wheel it push 28psi off a 71.1mm wheel is harder then off a 63mm wheel

absolutely!

That's my point exactly now get that 53.8 mill wheel to spin that 71.1 millwheel @ 150000 RPM

It's a hard thing to ask a 53mm turbine to do plus that turbine wheel that is too small to push the big wheel is being slow down by the big wheel at the fronts ability to suck big amounts of air through tiny pipes that turbine is struggling from many areas

[mr skidz]

Because I was aware of this issue before even buying that gt2871 turbo I ran it with a .86 rear housing.

(Well we may well also be witnessing the absolute maximum flow capability of the factory Inlet pipe work on the RB26)

which is good to know as we all know huge inlet temps show up as documented by Simon when trying to push well beyond that 450wkw figure.

So I still remain confident that a GTX2863 will overtake a -5 everywhere on the same boost with NO side effects unless pushing the factory inlet pipes beyond there capacity to flow.

No different to pushing a -5 to those pipe limits.

My 2c

[Roy]

Man the fark up. Tial 0.63 housings with the proper GTX2860 and comp cover high mounted with twin 35mm gates.

Go 0.86 housing with GTX2867

[sneakey pete]

Gtx 2871s with tial .86 covers you mean Roy

[sneakey pete]

gtx 60 wheel is the same size as a -5 wheel with a smaller inducer, but lighter, with the same flow rate, though at a slightly higher boost. Can't see it being bad...

And considering the 34 with the 63s on apparently felt like -5s, then I'd say the 60s should feel better than that...

Anyway, time will tell, I'm committed at this point regardless

[Roy]

Well i am making my manifolds...just hoping to find cheap used GTX turbos

[Mick_o]

Firstly im gunna apologize for my behavior even though Mr Skids started the aggressive personal attacks on me 1st.

Guess it shows how passionate about this shit we are huh?

Mr skids i believe you are blaming the wrong side of the turbo for the heat. Most of this heat will be caused by turbine pressures which obviously back up into the exhaust manifold causing the excessive engine temps. Yes in a street scenario you probably wont have these issues as having a blast here and there wont heat things up anywhere near what a track situation would.

BUT i do believe this back pressure hurts how the car can be tuned as such and also effects how the car drives off boost too.

Im gunna jump platforms here and use my Evo as an example here also.

I believe its very relevant example as its a much more efficient setup from factory without the packaging issues the GTR suffers from (probably 1 of the most formidable factory turbo setups on any car)

Companies like forced performance make stock replacement turbos for Evos which make huge numbers and have guys pulling 8 second quarters and will be far more responsive in comparison to a "big twins setup" on a GTR.

Im using this as an example because these stock replacement setups on the track seem more prone to lunching engines even with the same power figures as custom T3/T4 setups which don't suffer the back pressures in the turbines (which backs Simons theory up 100%) even on a completely different platform.

[mr skidz]

Simons R34 had 2x GTX63s connected to only one 3.5" exhaust tho, everyone here would agree a 4" exhaust would have been better equipped at removing that wasted energy.

Here is some food for thought if he had a map sensor and removed his cat back exhaust and dropped the inlet pipes of both turbos and ran them flat out naked on 33 psi I wonder what it would have done in terms of the heat build-up and power-torque output?

Edited October 9, 2015 by mr skidz