Turbo sizing questions

[MitsuDriver274]

I'm going through the process of selecting a turbo, I've definitely decided on the gt28 series but don't know exactly which one to run. Doing some rough estimates at 6k assuming 90% VE and a PR of 2.3 (~20psi) a 4g would flow 439 cfm or 30.7 lb/min. (2.0l*6000rpm*90VE*2.3PR/5660). At 1/2 flow = 15.35, and 1/5th flow (at PR of 1) = 13.35 lb/min




I mapped it out on a gt2860rs map and it looks to small (excuse the crude paint rendition) , did I make a mistake somewhere? And who's running this turbo currently and can give me some feedback on its performance? Doesn't really fall into the middle island all to well.

 

[Barnes]

Any particular reason you picked this turbo as opposed to an Evo3-16g? (I think they are comparable)

 

[MitsuDriver274]

I just picked this turbo to get a base map of where to go, either up or down in size. I'm not planning on making more than 350, but I also want the turbo to be running efficiently. But the main draw to the gt series is the ball bearing center section.

I raced one season with a evo III 16g and another with what apparently was an evo 4 turbo which made much more power on the dyno (218whp => evo3 vs 246whp => "evo 4") that was quite a gain given we were running a 34mm restrictor.

A friend recommended a gt2876r with a .48 housing, but looking at the map it seems a bit too big.

 

[MitsuDriver274]

Quoting MitsuDriver274:
I'm going through the process of selecting a turbo, I've definitely decided on the gt28 series but don't know exactly which one to run. Doing some rough estimates at 6k assuming 90% VE and a PR of 2.3 (~20psi) a 4g would flow 439 cfm or 30.7 lb/min. (2.0l*6000rpm*90VE*2.3PR/5660). At 1/2 flow = 15.35, and 1/5th flow (at PR of 1) = 2.67 lb/min




I mapped it out on a gt2860rs map and it looks to small (excuse the crude paint rendition) , did I make a mistake somewhere? And who's running this turbo currently and can give me some feedback on its performance? Doesn't really fall into the middle island all to well.



Edited: realized I made an error in calc 1/5th flow, changed the map too, comes very close to the surge line now.

 

[MitsuDriver274]

Here's those same numbers on a 2871r

 

Quoting MitsuDriver274:
I just picked this turbo to get a base map of where to go, either up or down in size. I'm not planning on making more than 350, but I also want the turbo to be running efficiently. But the main draw to the gt series is the ball bearing center section.

I raced one season with a evo III 16g and another with what apparently was an evo 4 turbo which made much more power on the dyno (218whp => evo3 vs 246whp => "evo 4") that was quite a gain given we were running a 34mm restrictor.

A friend recommended a gt2876r with a .48 housing, but looking at the map it seems a bit too big.



Did you make another manifold for the Evo 4 turbo? /ubbthreads/images/graemlins/dunno.gif

 

[RayH]

For reference, I believe the center cartridge and compressor of the 2871R was what was used on the AGP L1R/SS44 turbos. It might have also been used on the FP2544.

 

[MitsuDriver274]

Yea that what I don't understand anything evo 4-9 would spin backwards right? But that is what the shop claimed I wish I had written down the numbers on it. That's why I used quotation marks.