What Exhaust Housing Do You Recommend?

[brother_david]

Im upgrading my turbo, along with other appropriate mods, except internally which im keeping stock until this Autumn.

Horsepower aim this summer is about 400-450hp.

I will probably build myself a HX35/40 hybrid later on when im aiming higher.

Im going for the Holset HX35 but i dont know what exhaust housing to choose, the 12, 12.5 or the 14.

Cheers!

[Cjmartz2k]

I'm not too aweful sure on that one, but I would lean more towards the 14cm housing, especially if you are planning on a HX40 compressor wheel down the road. I'm about 99% certain that's what I had on my 35/40 hybrid, and the spool was great. Just a straight HX35 would be even more impressive I'm sure. Bigger exhaust side will make better pump gas numbers, at the expence of a few hundred rpm of course.

What kind of driving are you going to be doing with it? Also, remember their are 2 different compressors for the HX35. 8 blade is smaller, 7 blade is bigger/flows more. I've shoot for that one for sure. The 7 blade has a 60lb/min compressor map.

[zachscalais]

ive just put a brand new hx35w on my gtr, its got the 12cm^2 rear. LOVE IT!! way nicer then the hks t45 that was on it lol havnt been for a tune yet so i dont have any dyno results to show. wuldnt rely be that useful and engine mods wuld be different anyway. Any other questions shoot away!

[Cjmartz2k]

Really? Not too familiar with the HKS T45. What kind of power are you making? That turbo/ex housing just seems a little small for a RB26 to me, but that's not coming from actual experience, just guessing. Kinda like putting a GT30r on a RB26 in my mind. How's the spool? Glad to hear your happy with it. 7 blade or 8 blade compressor wheel?

Edited April 29, 2009 by Cjmartz2k

[zachscalais]

well 12 cm2 = 0.89 A/r, and after having the lag of the t45 this seems perfect lol

the t45 is basically and older journal bearing version of the t51, and a bit smaller.

full boost with the t45 was reached at a bit over 5g, and car was making around the 370hp atw on 13psi.

spool with the hx35 starts at 3g which is perfect for what i want! doesnt pull quite as hard as the hks did but definatly feels smoother and it sounds great spooling. will be getting it tuned on 20 or more psi, will see wat the curve comes out like and are hoping for some where around 500hp atw.

[zachscalais]

oh and for reference, t45 next to hx35w

Edited April 29, 2009 by zachscalais

[Cjmartz2k]

Ahh, pretty The DSM guys say that these turbo's don't really come alive until 23-25psi and start making HUGE numbers above 30psi. Granted, that's on their little 2.0L, so you'll be able to make better power at lower boost with your 2.6L.

One thing I forgot to say to the OP. Holsets have an anti-surge slot or "map width enhancement groove" as they call it cut into the compressor housing. This will let you up the boost a bit more with out surge which will let you get away with running a bit more compressor flow compared to what the exhaust side should normally handle IIRC. I'd still push the bigger housing, especially if plans for a 35/40 hybrid are in the future, but just more info for ya.

[CEF11E]

zachcalais, would you be able to take a shot of the exhaust housing for me? and what sort of wastegate setup did you use? internal gate or an external gate? Where is the marking on the exhaust housing telling you what size it is?

I have a HX35W and can not find the rear housing size anywhere,

Cjmartz2k,

thank you for your valuable contribution to this forum, its people like you that make SAU a great community

cheers!

[zachscalais]

hi CEF11E, i cant rely get in and take anymore photos at the moment. Im pretty sure the exhaust housing size was stamped on the front side of the exhaust housing, it was just the number '12' i think. Some where on this yellow highlighted face i possibly?

if you post up a picture of the numbers on yours we should be able to tell you

as for wastegate setup, im running an external hks 55mm gate, on a low rise hks mani.

so i blocked the internal wastegate on the hx35, i dont have any pictures of how i did it but ill try and explain,

using the exhaust flange that i got laser cut, i tapped a thread in it then wound a bolt and locknuts in so that the end of the bold holds the internal w.g shut. the end of the bolt pushes against the surface that ive got marked with red.

hope that helps? Zach

Edited April 30, 2009 by zachscalais

[brother_david]

Im getting alot of good response Really intresting reading, feels like i should go with the 14cm^2 housing since, as you said, im going for a HX35/40 hybrid later on.

Im gonna run a 38mm external wastegate welded onto the factory manifold.

I was thinking about how the a/r is calculated though.. as i've understood, and read, a/r means area over ratio and a 14cm^2 would give, using the ekvation

(PI*Dia^2)/4 or PI*radius^2 backwards:

radius=1,05cm

diameter 2,111cm

in inch devided by 2.54=

radius=0,41

diameter=0,83

So... is the size in a/r then 0.83...? Or have i just struck a lucky number slevin cause using the same ekvation i get a 0.76 for 12cm^2...

Am i about to loose it Doctor?

EDIT

Found this, seems like im out biking beut this explains how it works in detail

Edited April 30, 2009 by brother_david

[Cjmartz2k]

Welp, the discusion just went over my head Thanks for the compliment by the way, but I don't think it's warrented. The guys over on the DSM forum have done so much of the leg work already.

Just FYI, I ran a 38mm HKS wastegate on a HKS log style bottom mount with the 35/40 (yes, we had to chop the frame a bit) with no boost creep. Actaully the opposite. My boost would fall off a bit on teh top end, and I don't know if it was from the compressor running out of puff or the turbine was experiencing choke. That was by far the loudest wastegate I have ever heard.

[zachscalais]

^ i just had a look at your mod list, mine are simular to yours, hks264 cams, hks log low mount ect, 55mm hks gate, plus fully forged, ported and polished ect, so should be good once tuned!

these are the a/r conversions taken from dsmtuners.com

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

Edited April 30, 2009 by zachscalais

[Cjmartz2k]

Ah, cool. Mine's a HX40 though with twin 50mm gates But I'm still rocking a stock bottom end and it's a 25, so you win this time

One thing about that a/r list, I'm not sure how accurate it is, but more specifically, I think it doesn't mean the same thing compared to mitsu turbo's or things like T88's. I think each company makes up their own propritary labeling system, and some of the DSM guys might be basing that scale off of other companies. Also, is for sure not the same when you go from HX35 to HX40 to HX52. I can tell you for a fact my 19cm is not over a 1.00 a/r. My best guess is about a .81-.89 a/r for my 19cm HX40. My HX52 when compared to a T88 34D with a 18cm housing looks almost exactly the same.

[brother_david]

Im really grateful for your help Feeling more and more comfortable with going for the 14cm^2 housing, sounds like its the way to go when building a HX35/40 later!

[CEF11E]

thanks for the heads up dudes it looks like I have the 12cm housing on mine wich will be a bit small for the 30det but a hellava lot better then a stock 25det housings with 3071 bits inside the hiflow on there at the moment runs out of puff big time and comes on like a bag of sledge hammers. its a bit ridiculous really, it fries 255 semi's without trying in 1st 2nd and 3rd.

so i will be looking forward to getting some drive ability back!