The compressor map that garrett publishes for the 2871 is deceptive. At least for the 52 or 56 trim turbos, the compressor map is the same as what you get in a 3071r. It just looks thinner because garrett didn't fully flesh the map out.
Only "(3)" uses the small 48 trim, and it has both sizes of exhaust a/r available. The small a/r is labeled
Turbo p/n 743347-3 chra p/n 446179-31
(Direct Link doesn't work, gotta go to above link and click "GT2871 (3)" in bottom right.
FWIW Here is an interesting post by my buddy with a 3071 who went driving with me and my 2560. He was shocked how much of an advantage the 2560 had powering out of tight corners, while the 3071 only having a big advantage above 80 mph or more: http://forum.miata.net/vb/showthread.php?t=435110
The GTX2863 map appears to be similar to the small (48 trim) 2871 but is smaller (less inertia) and runs at higher RPM. May be a better speed match in spoolup so it gains a lot of spool without losing topend! Wait, it has even more headroom up top!
Last edited by JasonC SBB; 12-15-2011 at 04:20 PM.
I plan to have the 2863 soon.
I am thinking the S6 mani from BEGI, either their intake mani or a custom.
Oh, and Tial vband .86 housing...
I may throw in some cams too. i am looking to keep all of my same power levels and just have a better powerband.
Oh, I may stroke the engine too.
The 2863 really looks like some quality cats *** stuff..
More fun with maps. Now with 1.9L engine airflow overlaid. Note that these assume 100% VE. So for stock cams, peak power is the airflow along the 6000 RPM line.
The reason they are for a 1.9L engine is because the dude who made them used 0*C standard air density instead of 20*C. The difference is about 6%. I'm assuming Garrett use 20*C.
So a 1.8L engine will require 7% less flow.
I just discovered this. A company called Forced Performance sell a machined billet 68 mm compressor wheel called an HTA 68 mm wheel. It's meant to be mated to a 2860RS compressor housing after some machining. The resulting turbo is called a GT2868 or an HTA2868. They sell both whole turbos, and the upgrade package.
Supposedly spools better than a 2860RS with a better topend (dunno if this is true).
This is a great comparo thread! I think I'll be going with the gtx2867(also looking at the EFRs) for my power goals but random question for you guys that might know. What's up with these turbo's when they say max out put is, for example, 45lbs/min and they dyno and are putting down like 550? It's not usual but it happens, I've seen a few with e85, some with water/meth injection, some race gas and a few on straight pump gas. How does this happen if max outout is supposed to be 450 and they make more and sometimes signfigantly more?
Another question, since I'm looking into the 2867. How signifigantly different would this turbo spool from the .64 A/R tial housing to the .86 A/R tial housing? Also, what could I expect as far as differences on the top end power?
What would be the maximum safe boost on a gt2871? I'm about to order my turbo kit when my taxes show up and I've really been leaning towards the gt3071 but recently started lookin at the smaller one... I was think I could still get the same general horse power I want but it would be more responsive... Am I correct in thinking that? I'm shooting for about 325hp daily