And that illustrates another aspect of the anti-surge housing. The inlet is HUGE. On the GT2871 I am looking at it is 4" dia. and could be a problem.

 

huge is awesome.

steph, can you make anti-surge holes for, say, a 2876 compressor housing?

 

The 2871 surges (mildly) on a WRX equipped with a BOV. During spoolup, surge doesn't care whether or not you have a BOV anyway.

 

no issues with a 2871 on a 1.6L, i'd assume the same on a 1.8L.

 

How much boost on the 1.6?

 

17ish.

 

I agree, that is why I asked Thanks for the clarification.

 

Thanks Brain. Yeah if anything I would think it would be less likely on a 1.8L.

 

Yeah normally I would agree. That big nozzle should help airflow. But the problem is the S4 manifold shifts the turbo inlet downward quite a bit, so there is possible interference with the a/c and/or PS. Fortunately I have depowered the PS so that is no longer an issue. Just the a/c belt tensioner will be there which is a lot smaller and further toward the front of the engine.

And before the whole a/c debate thing starts, no I am not ditching the a/c

 

You could always use a 3"-4" coupler to use 3" tubing which will allow for easier intake path routing. Y8s has a HUGE intake, I love the way it looks but a complex routing for a cold air box with 4" tubing would be tough.

 

If I get the 4" inlet that is what I was thinking, probably a 4"-3" 90 deg silicone bending reducer right at the compressor inlet. Silicone Intakes has them.

 

so much for velocity...

 

If you mean from the elbow, not really. It is such a large cross-section there will probably not be much head loss through there.

 

I think he was talking about the inlet velocity of air. As you increase the diameter of the path the air travels, the velocity slows down as well. Vice-versa happens when you make the inlet smaller. Yay physics/fluid dynamics! However, the difference will be barely measureable so I wouldn't worry about it...

 

Exactly. Going from a 3" intake tube and a small transition to 4" just before shrinking down to your 2" inducer has got to do some interesting things.

a 4" 90° is all you need:

 

actually that pic is old. I have a new cell phone now.

 

well no actually I need to get down to 3" eventually for the CAI so I can incorporate both transitions into one.

I think the flow regime will be fine and will not amount to more than a minor loss by my calcs. I am more concerned about the clearance.

EDIT: Sorry I was traveling on business and did not have full access where I could see the picture above. That helps, thanks. After looking at yours, and looking more at the BEGI S4 system picts, I think it would fit with the 4" inlet if I use a 90 deg bend.