I know there must be a million of these threads. I've read a few that had good luck with the the GTX 2867R. And one that did not. I'm currently sitting at 220hp/ 229ft/lbs with a sr20 on 15psi. I'm sure I've reached the limit for this turbo. I'm looking to be in the 300-350 HP range and not looking to change my whole set up. I am open to other suggestions as well. Here is a list of my drivetrain mods.
Built motor 1.9ish.
BE oil pump
ACL bearings throughout
Supertech 8.4 pistons with wiseco rings.
K1 rods
BP4W head with stock valves and springs. Port and polished.
ID1000 injectors
LS coils
Flyin miata manifold and downpipe
full 3" enthuza exhaust.
mushimoto radiator with FM stage 2 fan kit.
MSM 6 speed trans. 3.63 rear end.
All tuned on DIYPNP.

 

The gtx2867r gen 2 is a good miata turbo. Not quite EFR, but should get you to your goals.

 

Thank you for your input. I know EFR is the go to turbo but I'm not so sure the cost justifies the extra return.

 

Gtx2860r gen2 @22psi. 93 octane. Built bp4w, 84.5mm bore, FM manifold, 750cc ev14, etc. I like the 2860 if you're going for 350

 

I'm building a nearly identical setup, and the turbo is my last decision. I've seen both the GTX2887R and EFR 6258 mentioned as the best options for a build limited by a 6spd.

I believe everyone considers the EFR superior, and I found it for ~$1400 at: https://www.tcsautomotive.com/produc...29764607017042

Any real reason to still consider the GTX after this?

 

The OP has the FM kit. I don't know if the manifold would properly place an EFR turbo forward enough to clear a downpipe. If it doesn't, then he'd have to buy a turbo + manifold/downpipe + having the exhaust re-fitted to accommodate the new downpipe. This could be quite expensive compared to straight dropping in the GTX2867R. If I was starting from scratch, I would go with the EFR any day of the week.

 

Whoops, totally glazed over that part. I haven't purchased any hots side parts yet, but good luck to OP!

 

I think the 2860 gen2 is a better chioce for 300-350 than the 2867.

I have a 2863, but that's a size they don't sell any more (the 2860 gen2 has basically taken over that space):



As for EFR vs Garrett -- the EFR is a great turbo, but packaging can be challenging in the Miata and there are fewer off-the-shelf manifolds/downpipes/etc available.

The EFR spools faster which is a big deal for a street car but less important on a track car because you're never below 4000 RPM anyway.

--Ian

 

I would have a hard time hitting 300rwhp (uncorrected) with a 60mm compressor. I am at altitude and drive a SC though.

 

I was hoping you would chime in, I always liked your build. Did you ever figure out why your engine was more knock prone? I'm doing something similar to you with my setup to get roughly 100 octane. I'm using race gas concentrate that brings 10 gallons of 93 up to 101 octane and it actually works pretty dang good.

Also I think Garrett did good with the gen2, personally I'm hitting full boost at 3800. I think the 6258 might be slightly earlier but I'm still not convinced the efr is the holy grail of turbos

 

The working theory is still that it's a combination of 9:1 pistons and a head that's been machined too many times. I haven't gotten around to taking it apart to check.

A friend of mine is building a track car with a mt.net standard bottom end, VVT head, and a 2860 gen2 with the FM2R plumbing, I'll be interested to see what it makes once he gets it running.

--Ian

 

I'm happy with my GTX2867R Gen1 at about 20psi. And the gen2 looks vastly better. I'm only making mid 300s on a NA8 head and cams on pump gas.

 

That's about what I'm making as well and it's not slow lol. I think the gen 2 spool better at least from what I can tell. I can easily get full boost under 4000rpm in 4-6 gear. 3rd is probably 4100 or so. .64 turbine obviously.

 

Mine is a .86 housing so it's a bit slower to 20 psi than that. Probably about 4800.

 

I have a recent datalog of a run I did in 5th gear. Starting at 2900rpm I hit 22psi @3800 on a FM mani. The .64 housing in my opinion is so much better. I'm gonna be on a dyno soon after I get a better intercooler and I wanna see if it's falling off up top. Driving the car it doesn't feel like it is.

I bought a lightly used gen1 2860 and put a gen 2 housing and wheel on it. The only difference in gen 1 and 2 are the compressor housing and wheel. I spent 250 for the housing and wheel from arashi, Taiwanese company makes really good turbo stuff. Garrett copy of the highest quality. Lol

 

My 2863 is full boost (about 20 psi) right around 3800 RPM. .72 A/R because it's the EWG housing.

--Ian

 

Yea that's exactly what I'm seeing on my turbo as well. It's not nearly as laggy as I thought it might be coming from a 2560r. I like the power delivery much better, more linear.

 

I've got the GTX2860RS Gen 1 - with the Tial EWG V-Band housing. I think it's 0.64A/R. Only recent pressure plot I can find is from the Dyno,

6 PSI at 3000RPM
14.5 PSI at 3500RPM
19.6 PSI at 4000RPM
21 PSI at 4100RPM

There's probably a bit more in that by playing with the EBC, but the guy doing the mapping said he thought it was starting to be limited by something at the top end something which I need to look into (could still add in more boost but power was starting to plateau).

Basic spec:

8.6 supertechs, standard VVT head, square top inlet, Begi large intercooler, FM 3" exhaust with the ceramic cat, equivalent of US 92 RON fuel.

 

The 2860 gen1 is most efficient in the 21-22psi range. That's right in the middle of the compressor map, above that it'll make more power but diminishing returns. Do you have a picture from the Dyno? Curious to see how it did.

 

I'll dig the sheets out and PM you - interested in your comments about the Gen 1 to Gen 2 conversion and don't want to hijack the thread.