Anyone know of anyone using a he551v and/or on a 1st gen compound setup?

Some more turbo info here:

https://www.dieseltruckresource.com/...e-t307026.html


Big question is the variable exhaust worth the few extra hundred dollers over a s400?

 

It certainly couldn't be worse that a fixed vane normal HX55. That being said, I would think that a VVT on the secondary would be far more beneficial than vice versus.

I'm sure you know, but the secondary pretty much does 100% of the work until 30% - 50% of the total max boost. Below 30 - 50% is where most trucks spend most of there time; thus, effecting this operation would yield the greatest result.

However, it may be possible to slew the vanes on the primary such that it comes in a little sooner than normal. No matter how you change the vanes though, it still takes exhaust energy to spin the turbine; to create a tighter flowpath on the primary in an attempt to get it lit quicker, means that you're expanding to a higher pressure on the secondary (and thus have less available energy to drive the secondary).

The only benefit I could see in this type operation is if, regardless of PR, you could utilize the vanes of the primary to keep both turbos in each of their highest effeciency islands at moderate driving conditions.

--Eric

 

Ya that was kinda what i was drumming around in my head aswell. I will fab a WG for the sec. when i go to compounds. I figure at the least the variable housing on the primary will allow one to fine tune the sizing to work best for the setup without have to change to a different size.

Some sources say exh. housing range is 9-32 and others 16-32, i assume the 16-32 would be the correct one.