Compounding with a hx35

[bwhite]

Just an idea. I have no interest in doing a compound set-up. Im a single turbo kind of guy. I just figured I would throw an idea out there.

 

[Mr Peepers]

Is there any compressor surge associated with compound setups? Really quick spool is great, but compressor surge is really sketchy.

To elaborate on my setup and make sure things don't get exaggerated, it doesn't spool as quick as my evo3 16g on the real world. Boost threshold is great and can get to 20 psi at 2500 while holding the brakes(maybe more but makes me nervous) but doesn't spin up to speed at will as quickly as the 16g did, likely just more mass and inertia. This is also why there is a big difference in gear vs full boost rpm. 2nd gear is around 4k, 3rd about 3.5, 4th between 3.2 and 3.3, and 5th is 3k or just after depending on what rpm you start at(this is where some compressor surge can occur). This is for 30psi. Comparing it to a clipped 16g is a whole different story and I'd actually say they are pretty similar, although it's been about a year since that setup.

 

[richard33]

Is there any compressor surge associated with compound setups? Really quick spool is great, but compressor surge is really sketchy.

To elaborate on my setup and make sure things don't get exaggerated, it doesn't spool as quick as my evo3 16g on the real world. Boost threshold is great and can get to 20 psi at 2500 while holding the brakes(maybe more but makes me nervous) but doesn't spin up to speed at will as quickly as the 16g did, likely just more mass and inertia. This is also why there is a big difference in gear vs full boost rpm. 2nd gear is around 4k, 3rd about 3.5, 4th between 3.2 and 3.3, and 5th is 3k or just after depending on what rpm you start at(this is where some compressor surge can occur). This is for 30psi. Comparing it to a clipped 16g is a whole different story and I'd actually say they are pretty similar, although it's been about a year since that setup.

and someone said with the 12cm backhousing on a hx35 mated to a open t3 manifold will see 20+ lbs by 4k. Just want to clear that up as well. I had this setup with good results but wasnt seeing full boost till 5k+ rpms.

 

[dsm-onster]

TimG (moderator) has logs in the holset threads with 20psi at 4100ish rpms. . . With his 12cm^2 housing with open exhaust manifold. And with the larger hx40 turbine wheel. In 3rd gear.

You'rr full boost is NOT 20psi

 

[99gst_racer]

Is there any compressor surge associated with compound setups?

I never experienced it with my set-up. I even screwed around with the throttle a few times to encourage it to surge just to see if it would, and it still didn't do it.

For the most part, the system acts like the smaller turbo is by itself. And I never had surge issues with smaller turbos like the 14b and the 16g when I ran them in the past.

 

[91stocker]

I never experienced it with my set-up. I even screwed around with the throttle a few times to encourage it to surge just to see if it would, and it still didn't do it.

For the most part, the system acts like the smaller turbo is by itself. And I never had surge issues with smaller turbos like the 14b and the 16g when I ran them in the past.

Hows it coming along with your new set up?