Michał

Hi all, i need some advice about my turbo build, i have vvt motor in my miata and i already bought garrett gt2560r some time ago as a start of collecting parts, then i thought about build fun 200+ whp car without touching motor, but that was some time ago, plans changed a Little bit and my hp goal also changed, now im lookin to reach something about 350 at the wheels and im worry about my 2560 Will be to small, something about setup that i have now

- custom intake manifold from honda with 70mm tb

- electric power steering

- electric water pump set from Craig Davies

Electric stuff gives me less hp loss at the crank

- forged china rods

- forged 85.5 supertechs with 9:1 CR

- arp head studs, new seals etc

- water methanol injection set from snow performance cause im from Europe and we dont have corn in our gas stations, Best fuel i can get is 98-100 Ron which is equivalent of USA 93-93+

I know easiest way is put borg Warner under the Hood but it is impossible, for me in Europe is Just to expensive compared to rest of this build. Engine is still buildin so it is Best and last moment to change my turbo, i saw gingium made 390 whp with 2560r but with corn and much higher compression

So what do you think, which option Will be Best?

- rebuilt my 2560 with bigger billet compressor whell

- change to gtx2860rs which i found in good price and also have billet compressor

- change to 2871r

I dont know about rebuild my 2560 give me enough Flow to make 350, so i also wanna ask which turbo spools quicker, gtx2860 or gt2871? Thank you for any advice

aju41046

The smaller compressor wheel (GTX) will have a faster spool up, and the GTX turbos have a reputation for spooling up wicked fast. For your goals I would agree that buying one of the two larger turbos would be better, plus you'll have the option to crank it up past 350 in the future should you wish to. The 2871 will give you a bit more headroom, but the 2860 will be plenty for your hp goals. I'd go with the 2860.

Compressor Inducer/Exducer
GTX2860: 46mm/60mm
GT2871: 53mm/71mm

Michał

2560 has opinion that spools really quick, how spool looks compared to gtx2860? If both turbo has same compressor size, they spool simmilarly?

aju41046

The measurements are nearly identical, the main differences being in the trim and A/R. I’m not knowledgeable enough to compare the spool between the two, but I image the GTX makes up the little extra weight in its internal technology. Give Garrett a call and ask them which would perform better. But didn’t we both agree that getting using the 2860 would be a stretch with your goals?

Michał

Yeah, before i wrote this post i thought gtx Will be perfect, i Just wanna confirm it and im curious how much spool i must sacrifice with bigger turbo, i Will look for some dyno data

shuiend

iTrader: (24)

I don't have data to give you now. But sometime this year I should be able to show directly the differences between 2554, 2560, 2860, Gen2 GTX 2860, 2871. I am also curious how much difference in spool the GTX line will provide.

If you have the money, I would go with a GTX over a regular 2860.

der_vierte

I have experience with both turbos in my car.
GT2560R and GTX2860R gen2.

Turbos feel nearly the same, the GTX just a tiny little bit slower transients and juuust a little bit less pep in the initial spoolup, like 2-6psi, but once it goes, it goes! The real difference is past 15psi, where the GTX flows a lot more and pulls hard to redline, it loves higher boost. 350 at the wheels with 98-100ron isnt impossible with it, but near the limit. WI can help in this regard.
I recommend the small GTX with your powergoals and WI, the 2871 is just a little bit slow with so much modern turbos available

Ken Hill

The attached dyno charts are from 2 different cars running built VVT engines, Skunk2 intake manifolds, and 3" exhausts. The blue trace is a GTX2860, the red trace is a GT2560, both are making about 15psi in the first chart. The GT2560 is making 16psi in the second chart. The GTX2860 run is the same in both charts. Only the GT2560 is different between the two dyno charts. All runs are on a Dynojet.

• Anything below 3500RPM, is spool up time. The GT2560 spools faster.
• Ignore the dip in the GTX2860. Boost was creeping above 5500RPM and I had to modulate the throttle to hold 15psi.
• At 15psi, and at 6600RPM the GT2560 is making almost 300hp. But it is maxed out on flow. Torque is already dropping off faster than the GTX.
• At 16psi the GT2560 is a torque monster down low, but the show is over at 5500RPM. Torque is dropping like a rock.
• At 5700RPM the GTX2860 is just hitting is stride. Torque is flat and power is in the 300s.
• There is easily 3500hp in the GTX2860 with more boost pressure.
• When I drove the GTX2860 car on the road after dyno tuning, the reduced spool up time was not noticeable. It just felt fast.

The GT2560 is great for anything below 280hp or so. Any goal above 280hp is better off with the GTX, with a small hit in spool up.

Dr.Sep

der_vierte

I get 330whp on a lightly built NA8 engine at 20psi on 102 octane. (MS3, 3" Kraken, HF cat, cops)
NB engines should crack the 350 because of the better flowing head

GrahamC

iTrader: (4)

I have a Kraken top mount and a Gen 2 GTX2860. In 4th gear on a slight uphill here are my spool numbers:

RPM Boost (psi)
3024 10.0
3218 13.5
3428 15.9
3632 18.6
3802 22.4

I'm pretty happy with it. I had it on the dyno and made 376bhp (UK flywheel horsepower ) at 20.5psi.

aju41046

Now that’s just damn impressive

der_vierte

No pissing match:
Mine does 15psi around 3100rpm in 1:1 gear, 3.6 rear end, flat road, pretty impressive

Michał

Really good numbers, can you write me rest of your setup? Also what fuel you running?

codrus

IMHO the regular 2860 makes no sense, you lose spool and barely gain any power (like 20-30 hp tops) over a 2560.

I haven't used a GTX2860, but have been quite pleased with the performance on my GTX2863. It's the same spool hit, but can do 100-150 hp more than the 2560.

--Ian

shuiend

iTrader: (24)

Cost is the real deciding factor between a regular 2860 or Gen2 GTX and such. The GTX line is several hundred more then the older ones. So if you are on a budget, the older turbo might make sense.

codrus

If budget is important then I'd stick with the normal 2560.

--Ian

der_vierte

THIS!

Average hp will be better, great for a street car

GrahamC

iTrader: (4)

Pretty much what's in my signature. Fuel is Shell V Power, which is 99RON in the UK (I believe that's around 93 in the US).

GrahamC

iTrader: (4)

Yup those are great numbers. I'll need to try it in 5th (my 1:1 gear) and report back.