This is a discussion on Fuel pump, injectors, TGV deletes and TD04 19T within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Originally Posted by T0rque Your going to retune anyway.. I would go with the 16g as well.. Yea it's another ...
From my understanding a big turbo with its big housing will need to flow more air than a smaller turbo to sustain a certain boost pressure.
Pounds per square inch..... The larger cross sectional area of the bigger turbine housing requires more air flow to sustain a given pressure than a small turbine housing.
Think of it terms of water for example, a very small hose, say the size of a straw wont need as much water flow to achieve a certain pressure as a garden hose.
So a td04 sustaining 18psi is not moving as much air per unit time as a larger turbo, whatever it may be. So 18 psi is not equivalent in every turbo. To think that is just silly.
I don't see what the problem is. The intercooler, intake and manifold, I think, will generally be able to flow pretty well. So I think the real variable is the turbo. If you are providing more air per unit time with a better/bigger turbo more air will flow through the rest of the air tract. It's not as if the rest of the intake system is maxed out by a td04 at 20psi. So more air from turbo means more air for everything. The engine is consuming more air at that point.
Last edited by metaldahlberg; 07-04-2011 at 04:37 PM.
this thread makes my head hurt.
Lead Wrench @ WTF Tuning, LLC
HAWK-EYE ALLIANCE #7878
2007 WRX TR
My work in progress. http://www.clubwrx.net/forums/off-to...ld-thread.html
eerk, it's still not making sense.
Let's just say for a minute that your turbo is compressing a totally sealed box (or, somehow, your turbo is working, but your intake valves are all closed for some reason). at 38psia, and a fixed temperature, PV=nRT - you can't escape that - this means that you'll get a fixed mass of air, no matter what's compressing it.
No obviously, the case is different, since there's flow, but it seems like this is a good approximation, until the intake valve opens. At that point, the pressure difference (multiplied by the area open) causes a force, that can accelerate a certain mass of air (fixed volume, no matter what, unless the temperature is different, etc.) through the hole.
Where does the airflow capability come into this (unless MAP drops significantly every intake stroke ???)
You're right about the compressor efficiency, to a point, but that's not the main change. It is certainly possible to find two turbos, run them at the same efficiency and pressure (but different airflows), and see a massive change in power...
I get that the greater the volume (well, really mass, but for the sake of the CFM comparison) of air you push into an engine, the more power. I'm just wondering HOW, with the same pressure, you can get more air to go in?
A sealed box is not a good approximation of a flow path. The air is going into the engine. A bigger turbo at 18 psi puts more air into the engine than a smaller turbo at 18psi. You are over thinking it. You are not taking into account that the engine is consuming the extra air.
I assume that would come from tuning the valve timing.