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Old 04-06-2010, 07:18 AM   #1
SWP sube
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Default 8cm hotside vs 10cm hotside

i searched.. but came up with nothing..
on an STi is an 8cm hot side good enough?
or would it be better to just get a 10cm hot side??
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Old 04-06-2010, 07:37 AM   #2
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Also keen to hear this discussion.

Some company (can't remember which) recently released a TD06-20G-10cm for stock position Subaru application.


FWIW, I think Mitsu Evos run 10cm^2 housings, although they do have short, twinscroll headers, which would aid in reversing any decrease in spool from the bigger housing.
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Old 04-06-2010, 08:53 AM   #3
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good enough for what?
a 350whp daily street driver, yeah...

the bigger the turbine blade then the hosing cm2 goes up....
this refers to the cross sectional area of the turbine entry point right where it meets the turbine housing circumvent

Garrett use the dimensionless A/R number to express the same thing
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Old 04-06-2010, 09:00 AM   #4
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also note
with the Mitsubishi 10cm2 twinscroll housing, each turbine volute will be 5cm2...
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Old 04-06-2010, 09:06 AM   #5
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Blouch started making a 20g with a 10cm2 housing.

We need more info on what you use the car for...
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Old 04-06-2010, 09:23 AM   #6
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Depends on where you want your power band. 8cm = 3-6K rpm and 10cm = 4-7K rpm.

Where do you do most of your driving in this car, street, strip, track, auto-x?
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Old 04-06-2010, 03:08 PM   #7
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Quote:
Originally Posted by stidoc View Post
Depends on where you want your power band. 8cm = 3-6K rpm and 10cm = 4-7K rpm.

Where do you do most of your driving in this car, street, strip, track, auto-x?
Those numbers are pretty meaningless. Even an 8 cm 20G can be a 4-7k turbo.
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Old 04-06-2010, 03:13 PM   #8
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Given the traditional mods and competent tuning, this is where the dyno plots are shaking out on the 10cm hotsides by Blouch. It's a generalization, sure, but one borne out by the objective evidence to date.

Quote:
Originally Posted by Byzantium View Post
Those numbers are pretty meaningless. Even an 8 cm 20G can be a 4-7k turbo.
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Old 04-06-2010, 03:30 PM   #9
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bumpppppp
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Old 04-06-2010, 03:43 PM   #10
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Dyno plots don't show everything. When you run bigger hotsides you will notice it's harder to make part throttle torque and boost. You'll find yourself downshifting a more around town. The engine feels more high strung.
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Old 04-06-2010, 04:28 PM   #11
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Quote:
Originally Posted by arghx7 View Post
Dyno plots don't show everything. When you run bigger hotsides you will notice it's harder to make part throttle torque and boost. You'll find yourself downshifting a more around town. The engine feels more high strung.
This is what I want to avoid on a street car. I realize others prefer this kind of car.
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Old 04-06-2010, 08:38 PM   #12
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it's the classic tradeoff of instant torque which then fizzles versus the top end rush
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Old 04-24-2013, 02:26 PM   #13
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Ok, any new opinions on this? Looking at a new FP GREEN HTA w/ the stock (64mm) compressor cover. I'm figuring with the stock cover, the 10cm2 housing would be of less benefit, and am leaning toward the 8cm2. Then again my motor has Kelford 272 cams so I want to make sure it works well with the turbo.
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Old 04-24-2013, 04:24 PM   #14
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Quote:
Originally Posted by tja1618 View Post
Ok, any new opinions on this? Looking at a new FP GREEN HTA w/ the stock (64mm) compressor cover. I'm figuring with the stock cover, the 10cm2 housing would be of less benefit, and am leaning toward the 8cm2. Then again my motor has Kelford 272 cams so I want to make sure it works well with the turbo.
Bigger hot side I would think if your cammed and don't mind lag. If you daily drive your car am mind downshifting go with a 8cm
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Old 04-24-2013, 06:18 PM   #15
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8cm vs 10cm is about preference.

http://forums.nasioc.com/forums/show....php?t=1981344

8cm keeps more at lower RPMs and 10cm moves things to higher RPM.
All about what you want.

It doesn't matter if you're cammed or whatever, this will affect turbo performance similarly no matter what the rest of your setup is like. It will always have a similar trade-off. You'll get one guy saying cams are made for top end and 10cm is best, then another guy will chime in saying you need the 8cm to make up for the low end lost with cams. Whatever, there are valid arguments to go either way... bottom line is you just need to take your pick.
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Old 04-24-2013, 10:24 PM   #16
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Quote:
Originally Posted by Concillian View Post
8cm vs 10cm is about preference.

http://forums.nasioc.com/forums/show....php?t=1981344

8cm keeps more at lower RPMs and 10cm moves things to higher RPM.
All about what you want.

It doesn't matter if you're cammed or whatever, this will affect turbo performance similarly no matter what the rest of your setup is like. It will always have a similar trade-off. You'll get one guy saying cams are made for top end and 10cm is best, then another guy will chime in saying you need the 8cm to make up for the low end lost with cams. Whatever, there are valid arguments to go either way... bottom line is you just need to take your pick.
Agreed he needs to decide redline power or a little more low end. No one here can decide that for you, unless you have certain power goals in mind.
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Old 04-24-2013, 11:03 PM   #17
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8cm hot side is ideal on a stock 2.5 for every day driving. Off-boost characteristics are insanely good, boost comes on a few hundred RPMs earlier than the 10's, and it still pulls like a big turbo.

Get the 10cm if you're seeing triple digits mph consistently.
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Old 04-25-2013, 12:30 AM   #18
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after having a 8cm TD06 20g for over a year, and then more recently a blouch dom3xtr 10cm.....

8cm if you like point-and-shoot, autox friendly powerband, and the 10cm is awesome for roadcourse, trackday work.

just my 0.02
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