Turbo Selection Help - GT2860R 0.57AR/0.64AR vs GT2560R
 

Hi All, I'm tossing up between a Garrett GT2560R or GT2860R with the 0.57 (Mamba wastegated Nissan flange) or 0.64 (Garrett wastegated) turbine housing and looking for recommendations or considerations for which of those turbos and ARs to go with for my goals. Motor will be a built BP4W (forged rods, head studs, new bearings and rings). Likely going to use a 3 valve EBC, kraken side mount manifold and 2.5" exhaust. Goal is about 160kw/215hp atw or ~250hp crank for reliability and a decent amount of performance. Ideally wanting a fast spool for drivability/fun with the intended use being weekends and a few track events a year.

Doing some research it seems common for people to use a 2860R with the 0.64 housing but I was considering the 0.57 for faster spool. The 2560R obviously spools faster (although I have no practical experience of how much by) but it looks like the 2860R would have a higher adiabatic efficiency at lower boost (which might be better for keeping the car cooler on track?) comparing compressor maps at 25lbs/min ("250hp crank ish" using the rule of thumb). I've also read that BPs apparently can be prone to pinging with a smaller AR turbine housing so the 0.57 may not be a good idea.

At your power goal, a 2560 is a GREAT turbo, especially for the price, no need for a gtx2860. I had both and the 2560 even felt a little peppier in lower boost levels

Thanks, I've been leaning more and more to the 2560 just for the responsiveness

For 215whp it might even be worth looking at the 2554. Being satisfied at 215 for any period of time is not easy though.

Right, you get used to power quickly and with a built engine and a slightly bigger turbo, he can just turn it up a little more

2560 seems decent then based on your oppinions, faster spool than the 2860 but still room for a bit more power whereas the 2554 would be almost maxxed out at 215hp

A SR20 T25/28 turbo off of Nissan Silvias/240s can flow just as well. The T25 is in between the 2554 and the 2560, and cheap, You can buy a used one and get it professionally rebuilt and balanced for less than a brand new Garrett. Note the S13/14 T25 is a journal bearing, while the S15 T28 is a ball bearing. I'll be getting my SR20 t25 build tuned in a couple weeks. Data on the T25/T28 measurements is a bit conflicting across the internet.
https://cimg1.ibsrv.net/gimg/www.mia...b42845f1dc.png
https://cimg3.ibsrv.net/gimg/www.mia...dad8f7cc7d.png

Theoretically, by measurements alone, you'll have quicker spool with the SR20 compared to the 2560. But it is a journal bearing so it's going to have more internal friction. As you can see the compressor measurements sit right between the 2554/2560, while the turbine measurements for all 3 are identical. I'm about $550 into my t25, that's the cost of buying it and getting it professionally rebuilt by GPop Shop. Last I checked 2560s are around $900.

All being said, you seem to have a good build capable of pushing far past 215whp should you ever want to in the future. The 2560 would allow you to go up past 250, while the SR20 would be reaching its limits around 250.

2554 - Depends on dyno I would say.
Mine made 280hp on a dynapack that reads very close to dynojets from what I've seen.

Thanks for the info! I reckon I've made my mind up on the GT2560R for now. The SR20 turbos could be a decent option although I like that the 2560 has almost 10% higher adiabatic efficency at 25lbs/min than that and the 2554 which is probably good for thermal management at the track and has some room for a bit more boost in the future