I am thinking about running twin he551v holset turbos in a rear mount configuration. The vgt will neck down to 19cm² at its tightest point on the 87x75 turbine wheel. Anybody know or can you venture a guess what that would equate to as a normal a.r. number. Im trying to rear mount two of these and run them on my 427 lsx. I was hoping to have decent transient response with these even rear mount becuase of the vgt but i just dont know enough about the holset turbine spec system to make even an educated guess. I researched but there seems to be about 9000 different answers to holset turbine size designation. Any help will be appreciated.

 

How are you planning on controlling the VGT?

 

The he551v is air controlled so im going to use a spare pwm output on my dominator to operate it. Car already has onboard air for dome pressure. Probably run it off of back pressurevs boost pressure. Not totally sure on besy control parameter but one way or the other i can control it no problem.

 

There's no direct comparison, and the ratio changes with the turbine wheel size. The general consensus is that a 14cm2 would be the equivalent of about a .8 on a 80mm turbine inducer. My guess is that the 19cm2 would be in the 1.00-1.10 range, but totally a guess.

 

Well after more research it actually necks down to 14cm2. Has anyone ever seen someone use two 551s for twins.

 

I should have said has anyone seen someone use hx55s as twins since the he551v is basically just a vgt hx55.