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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 02-17-2009, 12:11 AM   #1
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I know everyone's first thought to this is gonna be like noob let me google that for you. My problem is when i use to be in math class the teacher would explain it and i would be like wtf can you show me?
Turbo terms to know:



1. Compressor and Turbine wheels
2. Wheel “trim”
3. Compressor and Turbine Housing A/R



These items are the key elements that define a turbocharger and determine its flow characteristics.

In my case i have a greddy TD04-15C turbo

Compressor:
Exducer 2.187"
Inducer 1.654"
Trim 57

Turbine:
Inducer 2.042"
Exducer 1.735"
Trim 73

I believe those are the right sizes someone please correct me if im wrong.

Now the "G" and "C" compressor wheels flow a bit differently the C flows 8% less i believe.

I cannot find a 15C compressor map but here is a 15g map. Can somone explain this to me like there explaining it to a 14 year old kid.
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Old 02-17-2009, 12:16 AM   #2
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Old 02-17-2009, 12:25 AM   #3
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Boost is a measure of restriction. You've probably heard that before, but you probably didn't really know what it meant. See this thread to understand what that really means. https://www.miataturbo.net/forum/t31305/


Now you know why boost is a measure of restriction. So, on that chart you posted the vertical axis is labeled pressure ratio (boost, or restriction), and the horizontal axis if flow, in CFM. Say you sit at 14.7 PSI, or a pressure ratio of 2. Your engine will flow some volume of air at this pressure ratio. Say you're setup flows 0.15 (don't know what the units of this are, not but not CFM in this case). Anyways, if that's how much flow your motor moved at 14.7 PSI boost then your turbos compressor would be at ~75% efficient. See where that came from? Those curves in the chart show the efficiency.

Now say you put a 3" exhaust on this beast and a new set of cams. This improves the engine's VE and you get more flow and more HP for the same 14.7 PSI of boost. So now you might flow 0.20 instead of 0.15, which puts your turbo around 60% efficient. That's pretty much way out of it's efficiency range though. In this case you would want to get a bigger turbo.
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Old 02-17-2009, 12:28 AM   #4
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dude did you intentionally misspell "learn"?
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Old 02-17-2009, 12:29 AM   #5
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i see so you want to be on the islands. Thanks pat. Ive been reading the link from the second post. And one question. Is there an easy way to determine how much flow the engine/turbo can put forth?


Yep i lern 2 spel at w0rk
of course i meant to misspell it im not 14 lol
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Old 02-17-2009, 12:31 AM   #6
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Quote:
Originally Posted by sbkcocker499 View Post
Is there an easy way to determine how much flow the engine/turbo can put forth?
:bowr ofl:



Not easily. There's 11ty billion variables that dictate what the engine will flow.
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Old 02-17-2009, 12:39 AM   #7
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yea i kinda figured. Ill just shoot my foot.
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