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Question about air injection
I am curious about the air injection systems on these engines and have a few questions.
First let me assure you all "I did try SEARCH". As you might imagine all I could find about this system is variations on the theme "you don't need it, rip it out" , "That's emissions crap that only adds weight, remove it". I tend to agree but I wanted to know more about how it works. 1) Where does it inject the air? Heads I presume? 2) When does it inject the air? Which part of the stroke? 3) What does this air accomplish? 4) Where does it pull the air from? Thanks in advance. As you can tell from my questions I am not a mechanic. I am just curious about this appendix (we know it's there we just don't know why) in our cars. Kirk
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Kirk Crashed: Silver 1992 Turbo S2 Sold: '86 930 minor mods; '94 3.6 Turbo; '85 Euro 930 (3.2 Intake, Tec3r EFI, TwinPlug, Garrett Turbo, JE 8.1 Pistons, 505 rwhp) |
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09-17-2008, 05:55 PM
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Location: Ogden Valley area, UT
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air is injected into the head, behind the exhaust valve, but ahead of the exhaust manifold. It is a continous injection, and is used to dilute the exhaust gass for imissions purpose. Pulls air for the engine bay.
~Chris |
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09-17-2008, 06:25 PM
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by continuos injection do you mean it is still injecting air while the piston is trying to push air out on the exhaust portion of the stroke?
Thanks for the reply. Kirk
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Kirk Crashed: Silver 1992 Turbo S2 Sold: '86 930 minor mods; '94 3.6 Turbo; '85 Euro 930 (3.2 Intake, Tec3r EFI, TwinPlug, Garrett Turbo, JE 8.1 Pistons, 505 rwhp) |
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09-17-2008, 06:29 PM
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Location: Colorado, USA
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It's been a long time, but from what I recall, the air pump works in conjunction with the 2 way catalytic converter. Injecting the air into the exhaust does something to make that converter work better.
When Porsche fitted the 3 way catalytic converter in 1980, the air pump was no longer needed. Also, from what I recall, if you don't have a cat converter on the car, the air pump doesn't do anything significant to reduce emissions. |
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09-17-2008, 06:30 PM
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Location: Ogden Valley area, UT
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what I was told was that it was to merely dilute the exhaust, (my system did not have any other imission controls) and it had to be done "within the engine" and not in the exhaust system. that's why the injectors go into the head. A cat actually burns the exhaust up, while the air injection was just diluting it to acceptable levels.
Any yes, I believe it was/is continuous. No match for a rising piston. |
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09-17-2008, 06:57 PM
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thanks
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Kirk Crashed: Silver 1992 Turbo S2 Sold: '86 930 minor mods; '94 3.6 Turbo; '85 Euro 930 (3.2 Intake, Tec3r EFI, TwinPlug, Garrett Turbo, JE 8.1 Pistons, 505 rwhp) |
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09-17-2008, 06:59 PM
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1985 Porsche 930 3.3 turbo
