That back pressure reading is very surprising! I was sure that it would be much higher, like at least 2:1 or even 3:1. That BW sure does do it's job doesn't it!

 

Ya, it is pretty good for the boost, but the turbo is only making about 5 psi of 10 psi total boost with the 3.6 pulley and I'd have to guess about 3 psi with the 3.3 pulley. But the motor is still seeing the same overall air flow. I though that it was interesting that even with the big drop in pulley size the BP was the same. I'm guessing that's cuz most of the BP is not from the turbo so much as the WHOLE exhaust system, since this was all with the cut closed and exhaust running clear out the back.

It's funny, I used to think 10-12psi was a LOT! And now I'm like its ONLY making 10-12?!?... I want 15-17, since I've seen 20+ once or twice on the gauge

 

I don't know if your familiar with a 2 stroke's reed valve (one way air valve) but what if you mounted a couple in between the turbo and the supercharger? That way the supercharger could run without having to suck through the turbo until the turbo spools up. I was looking at an old turbo yamaha motorcycle schematic and they mounted one in the plenum so the motor had something to gulp when the throttle was cracked quickly. Should help response i would think.

 

I know what you talking about. I've worked on many 2stroke motorcycles, but the blower, especially with this setup has no real trouble sucking though the turbo. You step on the gas at any speed and the boost gauge goes right to 5-6psi with the 3.3 pulley.

 

Took the truck to the track was a little better then I though, but can use some improvement

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