Looking to convert my setup for road racing and as the engine and gbox are both built already was considering a turbo setup that can maximize hp but mainly keeping the road racing character, as old k24 or K16 might still be an option with some kind of billet wheels, porting,etc.. I still bet on the gt28, and to keep things simple I'm going to keep headers, external wastegates, etc.. Sell current turbos and replace with gtx2867. Anybody had any exeprience with these? Any info for the AR used? Guess the .64 should be better for our setup

 

No experience on this platform but I'd say that would be an awesome setup for response and still be good for 600++whp on the top end.

 

How much displacement are you running? A .64 A/R GTX2863 or a V-banded EFR6258 would both be excellent choices for a responsive road-racing type setup capable of up to 800whp

 

I guess should be over 750whp easily at the limit of compressor efficiency, GT-Rs are hitting 800whp easily with these turbos maxed out

I am running stock displacement, rev limit till 7200-7400 but I'd like to keep as much as possible till 7000 as still on the stock 996 lifters and everything else stock on the valvetrain.

I am worried the 2863 would be too small for 7000+ redline, if I would do EFR, would be the 6758 even I know 2863 and 6258 will build boost earlier, not sure if they will be faster as a lot of time will be over 4000 rpms where the one step bigger turbos like 2867 will deliver more power and still not too brutal like gt30s, so will be able to accelerate early on turn exits, might not be right here as this is my supposition

 

Hi Fadi,
You will want 2871's. They will come on hard and beat up your tires making them greasy. Some road coarse guys prefer 30's. Feel free to pm me or call to go over the best options.

 

I'm running 3071's with water/meth, open 3" x-pipe from eb werks, love the power band, tight turns under 40 go to second, even the back straights plenty of power even up to 150 mph range, especially at Daytona

 

Thanks guys for your opinion, I had alphas76 before and now I run even bigger gt30 based turbos being able to break 4s 60-130, and this kind of turbos is what I'm going to use for another build - gtx3076, but for the 911 I would go much smaller to have almost stockish spool and smoother power delivery, the gt30s hit too hard imo and controlling the car is difficult when they hit, we have to make sure keeping the car 4800-5000+ rpms to have control and therefor the power band will get a bit narrow.

I am quite positive a gt28 based turbo is what I want know, gt2871 I guess is the old wheel design and the specs of the nex gtx2867 seems to equal at least the 2871

The gtx2867 should get 750+whp at 1.8-1.9bar if I want to go all out, I plan to use the car bellow 1.4bar (maybe even 0.9-1.1bar for the track) where these little guys shine but produce plenty of power for the road coarse. the engine, gearbox, fuel system, suspension, traction, etc everything is there to support any kind of power, I would say this car should be like a 997 gt2 with hybrid VTGs but using a 996tt platform with gt28 based turbos, still have to do some breaking upgrades later but using Carbotech pads and SRF Castrol fluids should be ok for a while

Can anybody map the stock engine to a gt28 compressor map?

 

If you're not going to run extremely high boost, I think you'd be better off going with the smaller compressor (2863 vs 2867), as the 2867 is a little mismatched whereas the 2863 will be good for up to 40lb/min per turbo while maintaining ~70% efficiency. You could also go with an HTA68 upgrade from FP as HTA > GTX for given size, in both power potential and response... You could always fit larger hotsides later on if you feel you need more top end...

 

Just saw that Garrett launched the specs of gtx2871 on their site since January 2015...

To be very honest I would like to have them, guess they arent too big for the road coarse and as I run a pretty nasty fuel system I would go till 1.8-2.0bar now and then using racegas or meth. For the track I would use 1-1.3bar and for the road/daily 1.3-1.8bar.

Should be able to provide enough cooling to run them at very high boost - 4.5" ICs, water/meth injection... also 44mm wastegates and every supporting mod is there

they are rated up to 560hp each... so I guess 2x560*0.9(considering lower efficiency as my engine is almost stock)=1008hp !!!

I am almost set up to do it very soon, waiting for my gt-r to be finished and will start the turbo, should be a very efficient setup imo, will keep you guys informed here, thanks for your help

 

May I ask you to be so kind and PM me a log of your car? I would love to see how the 3071 are doing compared to my old 3076 and the bigger turbos I run now.. all being somehow in the 30s family but not quite

Thanks a lot !

 

Fadi,
There is no way a gt28 turbine wheel will flow enough for 560bhp/turbo. The gtx2871 is grossly mismatched, compressor wheel being significantly bigger than the turbine wheel (its basically a 5447-equivalent if such a thing existed)

 

Let me know if I can help you Fadi.

 

+1 I was wondering the same thing, but they state clearly 560hp even the common sense will say it's way too much, thanks for your input

I have seen some stating that the 71 wheel on GTX series is actually 73.5mm or so..

Anyway even the 2867s are rated 480hp, using the above logic will net 864hp, and 2863s about 780hp... more than enough I'd say

 

Once again, if you want something in the gt28 frame, gtx2863s would be a good match for a (stock) 3.6L motor. Another choice worth considering would be a pair of EFR6258s with the 0.85A/R V-band EWG housing...

 

just came to the conclusion that I really need to look at this as well... my days of mega high end speed runs >>> 180 mph are finished as my local private course has been sold and the local roads are so atrocious... so I need to focus on a quick 30-130 mph machine maybe..

would you go Gtx28xx or just do the K24 68 mm billets like Sam has in stock.

Would I need an ERP clutch if I run GTx28xx and E85 fueling aiming for say 650 rwhp