A small update on the new SX-R turbos. I installed the interstage drive pressure gauge and went for a drive to see what the ratio is with the new primaries.
The first few PSI stays almost inline, drive maybe one or two points higher. At 5 PSI of boost, drive hits 10, so roughly double—this is the worst spot. As boost climbs, drive stays about 5 psi higher, which shrinks as a ratio as boost climbs. At 20 PSI of boost, drive is 25, or a ratio of about 1.25. This is at 60 PSI total boost.
That was the highest number I hit on that trip; I meant to do a harder run, but traffic got in the way and I had to get home so I ran out of time.
I would have to look back in this thread to see what the ratio was with the 57 SX-E, but I seem to remember it being more like 1.8 or higher. For this application, I would say the new SX-R is looking pretty good!
I’d like to see what the total drive ratio is, but the plug in the manifold is seized (and it’s hard to reach) so I’ll have to deal with that another day.