After 5 years of use my GT2256V was starting to show its age, bypassing some oil on the compressor side and occasionally making a *woo* sound when it spooled up from idle.
Having a GT2359V from an E320 CDI on my shelf, I decided to combine the best of both worlds into a hybrid turbo. And the GT2356V hybrid VNT was born.
Great exhaust flow of the GT23 turbine with the well matched flow characteristics (to an OM617) of the 56mm GT22 compressor.
I had to make a new adapter plate due to orientation differences between the Sprinter and E320 turbos. The Sprinter flange requires a slight upward tilt for the turbo's outlet flange to be level where the E320 is square with the T3 flange. The rearward stud on the adapter plate is longer to accommodate the intercooler's support bracket.
Spool up speed is nearly the same thanks to it's VNT design.
The exhaust backpressure : boost ratio is now always close to 1:1 across the RPM range, the GT22 turbine was 1.5:1 most of the time and rose to 2.5:1 on the top-end.
I got rid of the flex tubes that coupled the GT22 outlet to the exhaust, it was a constant leak issue trying to seal the thin metal with a clamp designed for pipe. The outlet pipe is now a 3" od-od coupler pipe welded directly to the turbine outlet and downpipe flange, with the flange being bell-mouthed to improve flow stability.
That also got rid of the support bracket that bolted to the manifold, reducing heat conduction loss from the manifold to downpipe. Here the exhaust manifold pressure (EMP) pipe can be seen.
The only down side so far is its louder at idle, both with vanes open and closed. Sound level measures 84db at full power at 70mph, thats with the shorty pipe outlet at the passenger door and windows up.
Its been raining pretty consistently the last few days, so my water injection system is not able to work (vaporize) as effectively as it can. Once the weather warms up and dries up I will get a dyno run to determine what kind of power gains I got from the improved EMP:boost ratio. Stay tuned!