DelSolMarine

I made 670WHP @ 26 PSI with my PTE 6265 T3 .82ar exhaust housed turbo (b series)

I have sold that turbo.

I came across the BW S300SX FMW and have concerns about the size of .71 AR T3 housing that they offer. What kind of results should I expect with the FMW with this housing vs the .82 ar housing on the 6265 that I was running?

This change is coming because the oil pump cracked so I figured why not change the turbo at the same time as the motor work (pistons and hone). I will be upgrading the compression for a 9:1 piston to a 10:1 so they should also help.

There is also additional concern due to lack of space. I am running an AC Ramhorn manifold on my Del Sol and the 6265 fit rather tight but have seen people fit T3 S366s on this style manifold. I would assume i would have to make some minor down pipe modifications for the turbo to fit but that is not a major concern.

Airspeed

The A/R is smaller on the Borg turbo, but the turbine wheel itself is (much) larger at 75mm (iirc) outside diameter as opposed to the 65mm of the Precision.
So, what effect will prevail?
Hard to tell up front I think without trying it out or direct real life comparison.
On the up side: if it does fall on its face before full power potential is reached, you can just switch the turbine housing on the Borg as the basis (wheel size) is large enough.

DelSolMarine

While I think I was making relatively good power on a b series setup at 26psi (670whp) there were some signs of back pressure.

I wonder what the comparison on a 65mm wheel with a 82ar housing vs a 75mm wheel with a 71ar housing would be?

The compressor seems nearly identical on both turbos.

HoustonNFR

Off subject but how much did you sell your 6265 turbo for? I'm in need of one for my s2000