Turbo Effiency

[midnitehour]

So I'm confident that the GT2554r won't be able to keep up with my 1.8L
looking at the Compressor raio and air flow requirements it falls completely off the map for my power goals.

I'm currently looking at this
http://www.turbobygarrett.com/turbobygarrett/images/catalog/Turbochargers/gt28_images/750330-1&2comp_e.jpg

i've calculated to hit 300hp at 7000rpm.
with a ratio of 2.7161
air flow of 35.2106

where on the islands do I want to be for fastest spool up? more to the center or more to the right?

http://www.turbobygarrett.com/turbobygarrett/images/catalog/Turbochargers/gt28_images/472560-15comp_e.jpg

thoughts?

[starscream]

You would want to be on the left/centre of the island. Its where its the most efficent and the turbo is working at full capacity (basically your getting full use of the turbo).

The spooling part would be determined by how you size the turbo to the 1.8, and also the type of turbo (Journal Bearing, Ball Bearing, Ball Bearing Ceramic (uber rare and uber expensive)). BUT also if your looking at the GT28 Turbo specifically and from what it looks like it will suit your needs you want to be more to the LEFT/Centre. That is it would get to that goal (the corrected airflow number) quicker, going right would make it take longer because it needs get to a higher corrected flow number.

Although the differences in spooling with a properly sized turbo wouldnt really be felt too much, unless your consistenly hammering on and off the throttle losing all pressure in which case you can do other things to help with that.

[drunkmunky]

It looks like the 71R would be the better application for quicker spool time and increased efficiency. You're looking close to 75% in contrast with the 76R which is around the 70-72 range.

Can you input a lower RPM and produce some air flow numbers?

[Brian MP5T]

I believe that both are good choices, the trim difference will defiantly change how the boost is delivered, but unless you had two identical cars with the two turbos installed and drove them right after each other, you might never be the wiser.

Using the .70 AR should on paper let you run higher boost vs the .60... however I doubt you would ever truly notice.

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html