Turbo Query RHB32

Info is scarce on the RHB32 water cooled turbo, almost as rare as the turbo itself has become.
I've done some digging without much success, but wondering if anybody knows the
difference between the VZ5 and the VZ13?
They look identical, other than the water pipe manifold being a slightly
different configuration. One tube goes under instead of over, but that may not
necessarily be the difference...that could just be the water manifold.
Perhaps the compressor map? Or maybe the VZ13 is just the later model
of the VZ5? I found some reference to the VZ13 being an RHB31,
but also an RHB32.
Any info would be appreciated, all the other numbers on the tag are
very close.
IHI Catalog; scroll down and you will find the Suzuki family of turbos:

VZ13 RHB31CW-68002P14NRBRCL314BZ
VD110043 SUZUKI 14


VD110018 SUZUKI 14

The best I know is that there is a switch between mk1 and mk2; the one has a 31 mm diameter turbine inducer and the other has a 32 mm diameter turbine inducer.

Here some info that might be helpful: This is geared for 52 family, but still useful to decode.

General IHI turbo Info:

Here is some good info revealed about our turbine from the casting numbers: 2 k oD 52k 20R5

I don't know if the 2, K or OD mean anything but 52 means a 5200 wheel the 20 is the a/r and R5 is the material which is D5-niresist or high temp material for gasoline(not diesel). The 5200 wheel is 52 mm wide at the inducer tip.

For IHI, the A/R(Pxx) is in mm2/mm. It can be converted and compared to other turbines, which are more typically in2/in.

More good info about IHI turbos and their names/spec #'s:

The VI-34 (Isuzu Impulse turbo) number is called a short spec. V=Vehicle I=Isuzu (don't know about our "J" or "F") 34=the first 2 numbers in the long spec. The long spec is actually the part number on the IHI bill of materials or the list of parts that make up the turbo right down to the snap rings, nuts and bolts. RHB5 is typically called the frame size. RH=Right Hand(the direction the wheel rotates) B=Generation( IHI is now on F in 2005) 5=size range(5 is approximately 80hp to 250hp) Within a frame size things like shaft diameter and bearings are common.

Compressors: EX. stock compressor - VJ11 (spec: BRL3911) 39=39mm inlet, 11=???, BRL=Back Rake large (BRLL - very large). Back rake is how much the exducer tips of the compressor lean back. The more back rake the wider the map and the less pressure ratio.

Turbine wheels: 5200II=52mm inducer tip width. II=revision 2. I think all RHB5 turbines are 60mm in major diameter and 52 or 54 at the minor outlet diameter. You can stick a 5200II turbine wheel in a P9,P12,P15,P20 or P25 A/R turbine housing. Each increase in A/R shift the turbine hook to the right a little on the compressor map. In engine terms the larger the a/r the more lag and more top end.

RHB5 is a IHI frame size that was used in many turbos:
The RHB52w is found in our Mx6/Probe's with the VJ11 from 89-91. The RHB52w was also used in the TBird from 87-88(VJ17)[some sources say VC32M -for manual trans and (VC32A) for auto], 85-90 Isuzu I-Mark (VI-55), 84-87 Isuzu Impulse(VI-34), 90-94 Subaru Legacy (VF-11) and all 1.8L T subarus from 86-91. The VJ20 is in the 1.8L Mazda GTX the 88-98 1.6L 323 had a VJ-14 and the 86-87 2.0L 626 had a VJ-5.

The RHB52 was used in the 84-86 turbo Escorts(VC-31), the 88-89 Chevy Spectrum (VI-55), 91-94 Ford Laser-Capri (VJ-14), 84-95 Mercury Lynx (VC-31), Ferrari 208, and Bugatti EB110(x4). Fiat used them and it's a popular turbo for motorcycles. It was also going to be used in a TT version of the DeLorean, but the company supplying the parts went out of business before they could build them.
The RHB51 is found in the 94-91 Maserati BiTurbo(VM-4 and VM-5)

Some known RHB52 part numbers:
subaru turbos:
VF8 - RHB52XW - 10000 3X P20NR BRXLL4625CFZ
VF10 - RHB52XW - 5200 2 P15NR BRXLL4225CFZ
VF11 - RHB52XW - 5200 2X P15NR BRLL4016EZ
VF12 - RHB52XW - 10000 3X P20NR BRXLL4726CFZ

Isuzu turbos:
VI34 - RHB52A-100003P25NRBRL3911EZ 89-91 Impulse (Piazza)
VI37 - RHB52W-100003P25NR5BRL3911EZ
VI23 - RHB52A-100003P25NRBRL3911EZ

and the mazda turbos:
VJ11 - RHB52KW - 5200 2K P20NR5 BRL3911EZ
VJ14 - RHB52MW - 5200 2M P12NR5 BRKL3711EZ
VJ16 - RHB52MW - 5200 2M P15NR5 BRKL3911EZ
VJ17 - RHB52BW - 10000 3B P25NR5 BRL4016EZ
VJ20 - RHB52UW - 5200 2U P15NR5 BRUL3911EZ

RHB51 hold compressors up a BRL348
RHB52 holds all compressors up to the BRLL4625 (VF8 compressor).
A "W" on the end means it is a water-cooled center section. You can find RHB51W's and RHB52W's.