GT30
 

Looking at building a 325-350 hp engine. I'm assuming a GT30 might be kinda laggy for 350HP?



From what I have looked at the following turbos seem like they might work well:

-GT2860RS or GT2876RS

-Garrett 60-1 (might be a little large)

-T3/T4E .50 or .57 trim



I understand how the exhaust housing .ar affects spool and top end flow.



What .AR do you guys recommend that works well on a beta engine?

-.48 (maybe too small for top end flow?)

-.63 (seems pretty standard)

-.82

-Or some other size?



Hopefully this can turn into a discussion of various turbo sizes, wheel and trim configurations and .AR options and the affects of all on our engines. Please share if you have had any success experimenting with different combinations.

i recall an old J2 on my forum had a T04E with a small A/R, somewhere around .48 iirc. He reported it boosted nicely from 3000 rpm, and its peak power was 280ish hp. The GT2876RS seems to be a common turbo for 2 litre engines; isn't it the one known as a disco potato? If it is, it has been used on thousands of SR20s here in australia as a nice upgrade from stock. I'd be rolling with one of these.



Unfortunately there is no way to calculate how the A/R of a theoretical turbo will affect the way it boosts, you just have to rely on stories from others and guesstimates from compressor charts.



On that topic, can you read compressor charts? These can really help you if you know what level of boost you want to run. It is sometimes hard to find them for the more 'indie' turbos, like some KKRs and IHIs etc.

a GT30 BB would be a good size imo depending on the specs..



i would definitely go with a .48 A/R.



to do it cheaper, i would recommend a t3 .48AR/t4e 50 trim. spools great on the beta with higher end potential. 325-350 would be feasible while maintaining efficiency. i don't see the need to go to the GT/BB series turbos. If you are dead set on BB turbos, check out turbonetics GTK line.. Turbonetics BB > Garrett Imo.



this turbo would actually work very well and is affordable. it comes with a built in internal WGA. t3 .63AR / t4 .60AR



it will spool a little slower than a .48, but have a higher powerband which is nice for digs.