Thread: PCV help?
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Old 06-30-2009, 04:45 PM
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GregWeld GregWeld is offline
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Originally Posted by olds View Post
Okay, I've been trying to tell you it doesn't reduce exhaust temp. And for the last time tell me how this reduces exhaust gas temperatures?

Here's what you can do if you don't believe me, take a nice high dollar probe and stick it in your exhaust pipe, you can even use a fitting if you like. Take the temperature when the EGR valve is closed, the exhaust will be temp A.

Take the reading when the EGR valve is open, it will be temp A.

Recirculating gases and reducing pressure out your exhaust does not cool it in any way.
@Olds --

Let's try this one last time... because EVERYTHING I read about EGR systems say the same thing - they are present in diesel and gasoline engines because THEY REDUCE TEMPERATURES... Whether you choose to believe it or not matters little to me. I never knew what they were for until this thread started - and you started to argue about it. So... like I always do... I went out and researched what this system does.... and I learned a couple of things. #1 is that this system is in place to REDUCE TEMPERATURE... #2 is that, as usual, I never trust what anyone blindly states on the internet - and especially in a forum... because many people just think they know - and often times they're just plain wrong.

So here's how the EGR system reduces temperatures :

Exhaust gas recirculation

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in most petrol/gasoline and diesel engines.
EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. Intermixing the incoming air with recirculated exhaust gas dilutes the mix with inert gas, lowering the adiabatic flame temperature and (in diesel engines) reducing the amount of excess oxygen. The exhaust gas also increases the specific heat capacity of the mix, lowering the peak combustion temperature. Because NOx formation progresses much faster at high temperatures, EGR serves to limit the generation of NOx. NOx is primarily formed when a mix of nitrogen and oxygen is subjected to high temperatures.

So I think that TEMPERATURE REDUCTION is mentioned TWICE in just this one description of it's function. Vacuum isn't... that seems to be just a controller function and varies widely depending on the system.

Class is over on this one.
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