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If valvetronic, why is there a throttle body?
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11-04-2005, 08:00 AM | #1 |
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If valvetronic, why is there a throttle body?
All,
I was looking through pix o the n52 engine I took at a 3-er product pavillion when i was in Munich and I noticed something... a throttle body. I dont have the pix handy but have attached a pic from the part catalog that is referenced in the DYI forum. My question is this: with valvetronic on the engine, which is supposed to replace the use of a throttle body, why do we still have a throttle body? is it a failsafe? does valvetronic only work in certain engine regimes? |
11-04-2005, 08:16 AM | #2 | |
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Because it reamins fully opened, the aerodynamic losses are minimised.
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11-04-2005, 08:48 AM | #5 |
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All Valvetroic engines have this large throttle valve.
Its usually wide open, except at idle Its required at idle speed to help create a bit of turbulance in the incomming air , and to help maintain a nice stable idle. But then it goes wide open and stays there untill the revs drop enough ( it helps maintain a slight vacuume n the intake at idle speeds ) |
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11-04-2005, 11:04 AM | #8 | |
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be back in an hour or two... just kidding
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11-05-2005, 12:54 PM | #9 |
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So, some further research and talking to some engine engineers leads me to the following conclusion (other than the failsafe, which sounds feasible):
There are certain circumstances in which a sizable vacuum in the intake is required: -regimes that require EGR -canister purging the vacuum is required in these cases in order to draw gases (exhaust gas in the case of EGR, raw hydrocarbons in the case of canister purge) into the intake manifold. the throttle body is there to cause the nessacary pressure drop. |
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