Need advice on what compression to use 0.70 A/R Compressor, 1.05 A/R Turbine
T4 Twin Scroll Exhaust Housing
4" Anti-Surge Inlet
2.5" Compressor
- Turbine Wheel: 72.5mm/84.50 I wanted to use 10:1 but using a ls crank gsr block an b16 head it has become in possible unless custom pistons are made can 85mm sleeves hold up "erl block" I have found pistons for that bore also using turbo tuff rods an e85 fuel

 

I can get a set of wisecos in different compression ratios. 8.4:1, 9.3:1, 10.6:1, 11.4:1, or 13.0:1 for 84 mm

 

Use a flat top piston. Compression should be in the 10.5.1 range and it works perfect. IMO compression doesn't mean much... I have run 8.4:1 to 12.0:1 on 40-50psi..

Most piston manufactures work well up to the 800hp range then a higher quality piston should be used. My latest engine had a dish piston~ 9.8:1 off the shelf CP with upgraded pins they didn't have flat tops instock...

 

^^Everything he said.

 

I would sleeve the block to 84mm, this will leave room in the future if needed.. 85mm for high boost is not really a good idea in my opinion, it is great for NA guys but not so much if your going to be running higher boost levels.

 

So 10:6.1 sounds like it would work I just don't want that low compression lag I am also running a top mount and a open down pipe through the hood I just want it to spool fast

 

You'll be fine! Compression doesn't increase spool.