Why doesn't Garrett or Borg make these for tuner applications? - Page 6 - Miata Turbo Forum - Boost cars, acquire cats.

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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 04-07-2012, 01:01 AM   #101
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Soooo we need something to allow some of the flow to escape so the turbine can spin at a good rpm?
Very bad idea. Instead of surge, you would get overspeed.
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Old 04-07-2012, 01:07 AM   #102
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Quote:
Originally Posted by triple88a View Post
Soooo we need something to allow some of the flow to escape so the turbine can spin at a good rpm?
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Originally Posted by Savington View Post
Very bad idea. Instead of surge, you would get overspeed.
I thought that was a wastegate?
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Old 04-07-2012, 01:20 AM   #103
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Originally Posted by RattleTrap View Post
I thought that was a wastegate?
Wastegates do under normal circumstances. In this case we have significant load on the compressor causing airflow through it to slow, thus skyrocketing the AoA on the compressor blades causing a surge/stall. Sav is suggesting that venting the pressure in the line would cause the compressor blades to accelerate since they would have a decreasing load. Kind of like accelerating your car then pressing the clutch in with the accelerator still floored.

Sav, I know the applications are apples to oranges, but in aviation we have relief valves that allow the intake charge to speed up, it has little effect on the speed of N1 (the blades) as they are maintaining rpm because they are being driven, though they are wanting to slow down due to the reversion. Allowing the intake to pass evens it out.

I'm not convinced this would create an overspeed.

Last edited by tasty danish; 04-07-2012 at 01:30 AM.
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Old 04-07-2012, 01:20 AM   #104
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Very bad idea. Instead of surge, you would get overspeed.
I'm not talking a 3" hole.. i'm talking a small hole that closes at x rpm.

Wastegate is on the exhaust side, we're talking about intake side.
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Old 04-07-2012, 01:30 AM   #105
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Quote:
Originally Posted by triple88a View Post
I'm not talking a 3" hole.. i'm talking a small hole that closes at x rpm.

Wastegate is on the exhaust side, we're talking about intake side.
Bingo. You basically just described the system I'm talking about. Nice job.
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Old 04-07-2012, 02:04 AM   #106
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bottom line: on our poorly flowing low displacement motors there isn't much you'd be able to do with 25psi out of a 600whp turbo at 2500 rpm.

So no matter how much the kiddies have wet dreams about "OMG SPOOL AT 1500 AND BOOST EVERYWHERE, it simply defies physics.

You want spool at 1500 get a 10L+ diesel.
You want power at redline get a honda.

You want a watered down compromise of both, get a miata

/thread
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Old 04-07-2012, 10:57 AM   #107
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Ha, ok for some reason I was thinking the the VGT was on the compressor side.....my mistake. But, why dont they do the VGT on the intake and exhaust sides? I know that would make it even more complex but at the same time make it that much better if operating properly.


Hmmm....actually I dont even know if it would help much if any at all. Thoughts?
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Old 04-07-2012, 12:04 PM   #108
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Well sure it would help. Having a variable blade compressor AND turbine would be sweet.

Why not also have a variable A/R housing too? FU YEAH
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Old 04-07-2012, 12:11 PM   #109
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Why not also have a variable A/R housing too? FU YEAH
Approaching overkill....the variable vanes act like a variable housing
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Old 04-07-2012, 02:04 PM   #110
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why not just have variable everything

lol
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Old 04-07-2012, 02:54 PM   #111
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Quote:
Originally Posted by 18psi View Post
why not just have variable everything

lol
Yeah variable exhaust for variable backpressure too!!!!

And variable IC for variable charge cooling!!!

And variable tire size for efficiency vs speed!!!! OMGZZZZ
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Old 04-07-2012, 05:40 PM   #112
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The vanes dont work this way... That's why the they are not on the compressor. They direct the air flow at an angle, that's all they do. The closer to a right angle they are, the more the turbine is pushed, the more rpm can be achieved (with the amount of exhaust gas). That wouldn't do ---- but block flow on the compressor side.
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