twin scroll hx35 exhaust help!

[Jun3bug]

I've been trying to find an exhaust housing for my hx35. I have the t3 bep housing but just bought my twin scroll manifold and want to buy the matching housing. I can't find the difference between the 12cm, 16cm or the 18cm as far as spool, horsepower or response.. can anyone help point me in the right direction?

 

[atownturbo]

12cm would probably be your best bet since your stroked. Which bep housing? The 12cm is close to .89 a/r IIRC. But you get better spool time with the twin scroll so you don't have to rev so high.

 

[Jun3bug]

thanks man, exactly the info I was looking for...i have the .70 ar bep housing

 

[LandSpeed-DSM]

FWD with a 2.3/BC272 combo and a twin-scroll HX35? Which HX35 compressor wheel do you have?

What airflow/power goals for the car?

What valve springs? What intake manifold?

I would be leaning towards the 16cm2 housing and redlining in the 8250-8500rpm area, provided that small of a cam and whatever intake is on the 2.3 aren't falling on their face by then.

It will be plenty responsive and still have that top end you look for in a bigger than stock turbo.

My 274/280 cammed 2.0 with the S200sx in the bigger BW twinscroll T4 housing was still very responsive even with less displacement and hauled the mail out the top end.

You have a FWD remember? It's all about mid-range and top end if you aren't on slicks, straps, bars and springs.

 

[JusMX141]

Only the 12cm and 14cm HX35 housings are wastegated. Anything larger is non-gated, meaning it's large enough to control boost on it's own on a diesel with roughly three times the displacement of our cars. That's bad news for spool and overall boost production.

The 12cm housing is larger than you'll ever need unless you're building an all-out drag setup and throwing a ton of boost at it.

 

[LandSpeed-DSM]

Large displacement, yes, but low rpm and usually poor VE/restrictive heads.

16cm2 nozzle area is ~1.15-1.20A/R, but its a divided housing so it's not enormous.

It's still only a ~60mm major inducer turbine

Anyways, just my opinion.

 

[99gst_racer]

12 cm2 = 0.89 A/R
16 cm2 = 1.13 A/R
18 cm2 = 1.33 A/R

I'd stick with the 12cm housing as well.

 

[LandSpeed-DSM]

[(cm^2 x 8) - 7] / 100 = A/R

6 cm2 = 0.41 A/R
7 cm2 = 0.49 A/R
8 cm2 = 0.57 A/R
9 cm2 = 0.65 A/R
10 cm2 = 0.73 A/R
11 cm2 = 0.81 A/R
12 cm2 = 0.89 A/R
14 cm2 = 0.97 A/R
15 cm2 = 1.05 A/R
16 cm2 = 1.13 A/R
17 cm2 = 1.29 A/R
19 cm2 = 1.37 A/R

So not bad for doing it in my head. It also depends on where in the scroll case you are measuring the centroid.

This comes down to personal preference. He does have displacement on his side.

Edit: that formula doesn't take radius into account (centroid location in the volute) so I still stand by my 1.15-1.20 A/R equivalency.