Who has changed 475 to ?

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ws6 blackbird

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Who has changed from a generic 475/96/1.32 to a 77 or 78 with a tighter housing on there primary on a 12 valve? How much better?
 
Well, I'm in the middle of that transition right now. Started off by upgrading a 75/96/1.32 to an ETR-HO 80mm compressor wheel. Then I lucked into a 1.10 exhaust housing for the 88/96 wheel. I haven't run it yet though. Just started machining my 62/65/12 for 28-30mm wastegate pucks, that will be sitting on top of it.

I'm hoping to end up with a really quick spooling set of twins that still has a big top end. Oh yeah, the primary is setup for an egate too, just in case I need little control over it.
 
Drothgeb said:
Well, I'm in the middle of that transition right now. Started off by upgrading a 75/96/1.32 to an ETR-HO 80mm compressor wheel. Then I lucked into a 1.10 exhaust housing for the 88/96 wheel. I haven't run it yet though. Just started machining my 62/65/12 for 28-30mm wastegate pucks, that will be sitting on top of it.

I'm hoping to end up with a really quick spooling set of twins that still has a big top end. Oh yeah, the primary is setup for an egate too, just in case I need little control over it.
Click to expand...

Did you run the low 11s ETs with the 75 cast or 80 ETR?
 
Neither, that was with a 80mm cast wheel. With a 75mm cast, I was 11.7s. With the 80mm cast it went 11.2s with standard cover, high 11.0s with race cover.
 
So race covers actually make a difference.. I just went with 2 plain cast wheeled turbos, because I never saw proof supporting anything adding anything. I think I'm running out of fuel on the top end. It pulls real hard and feels strong on the bottom, but higher rpm and higher gears it feels like a dog...
 
dixon700 said:
So race covers actually make a difference.. I just went with 2 plain cast wheeled turbos, because I never saw proof supporting anything adding anything. I think I'm running out of fuel on the top end. It pulls real hard and feels strong on the bottom, but higher rpm and higher gears it feels like a dog...
Click to expand...

The standard cover is a .63 AR whereas the "race" cover is a .66 AR. So, the benefits depend on the compressor wheel. A .63 matches up fairly well with a 75mm, but it's starting to get a little tight for the 80mm. So it doesn't help the 75s much, but helps the 80s more. It's not a lot, but it is some(.13 and 2mph in my case).

The cast/billet wheel issue depends on the design. A billet copy of a cast wheel isn't worth the upgrade. But, if the design is better, it may be. The ETR 80 is not a drop-in. The compressor housing has to be milled larger to fit it. While the inducer is still 80mm, the exducer is ~4mm larger than the cast 80s, and the blades have more surface area. So it flows around 5% more air, and it's 30 grams lighter, so it may spool faster.
 
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