On my Syclone ,the housings are in CM so w/this chart I can give a bit of info on housings I have used or friends have used that I drove there Syclone. I personnaly own all the housings I made comments about. *IIRC, turbine measures 58.8/67.2mm
If you want pics I can post them. MHI Turbine housing areas:
6 cm2 = 0.41 A/R 7 cm2 = 0.49 A/R 8 cm2 = 0.57 A/R Stock Syclone 8 CM,works great w/2100 stall 9 cm2 = 0.65 A/R 10 cm2 = 0.73 A/R Also works good w/2100 stall 11 cm2 = 0.81 A/R 12 cm2 = 0.89 A/R Takes a while to spool up needs closer to 2400 14 cm2 = 0.97 A/R Minimum 2600 w/lag, 2800 + Stall is better for fast spool-up 15 cm2 = 1.05 A/R 16 cm2 = 1.13 A/R 17 cm2 = 1.29 A/R 19 cm2 = 1.37 A/R *Note: The Syclone engine is a 262 CI 4.3 engine,which B.T.W. is bigger thaan a 250 4.1 liter. Now these are T3 housings That I have personnally used on my Syclone & friends Syclone,T3's flow different than a T4, a T4 will give you more lag time than a T3.
You can learn from other guys as I have about stalls needed to run .63, .84, .96 & up A/R's on T4 turbos, from journal bearing to BB. Remember the Syclone is a bigger engine than a 250.
You can also learn from guys on the Buick forums,stock engine size is 3.8,but they also run 4.1 liter 250CI & they have sponcers,that help them pick turbos & what stall to use.Those Buick guys have recipe engines & they know what works to run basic 12's, 11's 10's ,9's & faster,they made so many Buick GN's T-Types & there is a wealth oh knowledge over there on those BB's
