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GTX2867R or GTX3067R T3 flanged ?

The red line is what's known as the lug line and represents where the compressor is operating during a wide open throttle (full load) pull up through the engine's rev range.

In order to increase mass airflow through the engine, you'll need to change far more than just the turbo - so you are on the right track with the 531 head, and ported manifold. MrBill has a good question, have you considered the B21F (naturally aspirated) intake? At any rate, you should keep going on the quest to remove flow restrictions, make sure you are using the largest (least restrictive) intercooler you can find, nice large radius bends in all the intake tubing, 3" exhaust or larger, and so on.

Yes it's always safer in terms of detonation to make more power with flow vs. pressure ratio. But if all you did was change the turbo, that lug line stays pretty much where it is, and the map shifts to the right. And yes, with a GTX286R or 2867R the lug line will also stay approximately in the same place and the map will shift to the right. All three of the GTX28R turbos have surge lines that are pretty close to each other so it may not be too bad in reality. Also the design of your intake system greatly affects surge performance - in a nutshell: less restriction gives you more surge margin.

With a journal bearing turbo, running off the left side of the map into surge can cause issues with intense thrust bearing wear. The rapid pressure oscillations cause the whole rotating group of the turbo to plunge in and out along the axis of the shaft. With a Garrett ball bearing all the thrust load is taken up within the bearing cartridge since it's an angular contact design (like a wheel bearing) so the main thing to watch out for is blade failure on the compressor wheel from the flow oscillations. It's not "safe" to run in surge per se, but these turbos can tolerate it up to a point.
 
In order to keep the b21 intake, i have to drill injector holes on the 531, which i really don't want to do. The B21 intake does not have injector holes on it, neither the 531 head . So .. since the b23 intake is better tuned and more free flowing, while has spots for injectors .. it is chosen :)
Also has different position of injectors which helps atomization of fuel.
I am not sure though why you mention B21F NA version, what difference it has from the B21ET or B23 intake.

Ok, i understood all you said, but the question is (theoretically - i am keeping your word anyway) why the 2863 and 2867 are also not a good choice since the maps are fatter (ok the map moves right) ? Of course not by changing the turbo only but the whole "top" system (intake, head, exhaust, manifold) as i described earlier.
I am still not sure why we choose pressure over flow, since all this stuff is changed. Maybe you mean that whatever i do this setup will never be so good flowing to support bigger flow, and the only solution is to up my displacement in order to have more exhaust gases?
 
As far as the intake manifolds, the B21F manifold is an equal length, longer runner setup than the B23/B230 intake. Still no injector ports though.

The B23/230 intake was the big thing a few years back, before the B21 intake was the next big thing. ;)
 
the question is (theoretically - i am keeping your word anyway) why the 2863 and 2867 are also not a good choice since the maps are fatter (ok the map moves right) ? Of course not by changing the turbo only but the whole "top" system (intake, head, exhaust, manifold) as i described earlier.

For your power goals with the B21FT, the GTX2860R has more than enough extra capacity to keep up with breathing improvements you make to the engine in the future. It doesn't really matter how fat the map is if you aren't using all of it.

I am still not sure why we choose pressure over flow, since all this stuff is changed. Maybe you mean that whatever i do this setup will never be so good flowing to support bigger flow, and the only solution is to up my displacement in order to have more exhaust gases?

The choice is made by the builder (you in this case)...whether you want a smaller displacement, more "peaky," higher boost engine, or a larger, torquier and lower boost engine at the same power level. The torque curves will have a very different shape in the mid range, and the choice just depends on your preference and how the vehicle will be used.

With all of the flow work you're doing and the 531 head I'd guess that your engine will more than make up for the 0.2 liter displacement difference vs a mostly stock B23 or B230.

To clarify, displacement isn't the only solution to increasing flow. In simple terms, airflow through the engine is governed by displacement, volumetric efficiency, and engine speed.

You can increase VE which is what you're doing with the manifolds, porting, and head work. You could keep going and do a ported 16-valve head which would improve VE quite a bit and move the whole lug line curve to the right on the compressor map, without affecting displacement. Increasing engine speed would also add more points to the right side of the map if you could get it to operate efficiently at higher than 6000 rpm, but wouldn't affect the location of the current operating points.

Hopefully this is all clear - my recommendation with your current stated setup and goals is the GTX2860R.
 
Parts Ordered :)

My Christmas gift to myself is on the way :p

Many thanks to everybody here, especially Chris and Gary !!
 
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Awesome. Please post up results when you get it all together and running!

Hi @Duder

Sorry for the massive thread revival, but I was hoping you could help me with a Garrett query if you're still there. I know I'm new on the forum, but I am at least an ex turbo Volvo driver

I'm looking to upgrade the standard turbo on my Subaru Legacy I've imported from Japan. It's currently got a VF45 twinscroll, but I'd like to aim for 420-440hp, so I'm considering a GTX2867R, however I can't seem to find any internally gated twinscroll options. Did Garrett ever get round to developing these? I'd rather not go into the GTX3071 range for a twinscroll, as I'm trying to keep lag as low as possible

Compression will be 9.5:1 on the new short block.
 
Hi @Duder

Sorry for the massive thread revival, but I was hoping you could help me with a Garrett query if you're still there. I know I'm new on the forum, but I am at least an ex turbo Volvo driver

I'm looking to upgrade the standard turbo on my Subaru Legacy I've imported from Japan. It's currently got a VF45 twinscroll, but I'd like to aim for 420-440hp, so I'm considering a GTX2867R, however I can't seem to find any internally gated twinscroll options. Did Garrett ever get round to developing these? I'd rather not go into the GTX3071 range for a twinscroll, as I'm trying to keep lag as low as possible

Compression will be 9.5:1 on the new short block.

Hi and welcome! No, there were never any twinscroll internally wastegated GTX turbine housings from Garrett. There may be 3rd-party housings fitting this description made to fit the GTX28 or 30, but I'm not sure. There are so many shops and companies out there who modify these turbos, adapt other housings to them, and make new housings for them. The GTX28 lineup is still out there but they have been replaced with G25, so keep those in mind as well.
 
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