FM2 GT2560R vs GT2860RS, think spool. - MX-5 Miata Forum

Wut?

all those FM plots have crap for top end. not sure why, but i suspect if they were tuned better you'd see more of a difference.

The Gt28 is larger so of course it will spool slower. It should also allow for more timing to make up some of that. That difference does not seem right based on my what I have seen on other cars. The larger turbine should result in much better top end. Not sure why Keith was not able to tune for that.

The Miata community is the only place I have ever seen so much love for the GT25 over the GT28. Not that the 28 does not have it's issues. The compressor offerings are less than optimal hence my original suggestion for the Tial billet compressor wheel in a GT28 frame. With that compressor we saw spool 500 RPMs sooner without any changes. I wish someone would try that setup on a Miata.

Altitude likely plays a role.

it's not love for the t25 over the t28. the t25 just pairs better with .64. i'm giving love to the t28 w/ .86 and so it pretty much everyone else. "upgrading" to a 2860 with .64 housing is like if iphone 5's were out and you had an iphone 4 but you got the iphone 4s instead. except for the 2860 has slightly better top end in the right scenario and less tq in the low end so it's more of a wash. it's more like buying another iphone 4 to replace your iphone 4.

the 2560 is just a better turbo for a 1.6. I'm not just saying that. nearly every dyno ever compared shows it. the 2860 with .86 in the correct scenario could be a different story.

.64 housing.

Jason - or others,

Did you actually run a 2860RS but swap in the .64ex housing?

I'm thinking of going tial v band housing on my disco but running the .64 turbine.

How was your spool and mid and top end? What motor, manifold, psi etc.?

I'm street only driving and have a goal of around 300hp on a built vvt.

Well, since you bumped the thread anyways... in for anyone elses recent 2860rs experiences. I'll be finding out for myself soon enough :giggle:

Did you use an electronic boost controller with boost rising with RPM to get that flat torque curve?

Keith

At altitude a turbo leaves it's efficiency island in the compressor plot much sooner. The pressure ratios on the plot are the same (obviously), but the inlet pressure at the compressor is significantly lower, so to get the same boost pressure you actually have to run a higher pressure ratio moving you up and out of the efficient range of the turbo at the same boost pressure that would be very efficient at sea level.

Keith

To review my question - on the street will the .64 turbine housing kill all that's good about what was originally a disco potato? Will I get steamroller torque but a capped top end?

OP,
Just turn the damn boost up.

You have a built bottom end with super low compression, why are you still at 17 psi?

edit:
Fucking 2012 thread. OP's B6 probably blew up by now.

Blame me for reviving this, and for bringing sexy back....
Too late - I just committed to a .64 Tial turbine housing, it was the only way to convince myself to go v-band. It was cheap and being v-band I will probably review my turbo options next winter after a summer of driving my 2860R.

I have no direct experience but I'm pretty sure Sav/Hustler both say that the .64 housing sucks and to pull up your skirt and run the .86.

Ha, when I do it'll be a 2871 to go with it most likely

Is it to late to change your order? You should get the .86 and purchased this from the for sale forums:

https://www.miataturbo.net/miata-par...flanges-77544/

Then you could try out both and let us know the results!

Keith