intake pic
09-09-2008, 07:20 AM
#25
AudiWorld Super User
Just have somebody rev the engine with the beauty covers off
Here is a picture of the single diaphram on the 32 valve motor, the 40 valve motor has two of them.
Once a certain RPM is reached, the diaphram relaxes (as shown in this picture) and changes the length of the intake runner in the manifold. So you'll see it "suck in" and "relax" as the engine is rev'd.....somewhere around 3,000 RPM as I recall and for the 40 valve, there are two RPM's that cause each one to move.
At least I think it's normally sucked in. If your linkage is broken, it's probably because it's seized.
<img src="http://www.audipages.com/Tech_Articles/enginemechanical/tbp12.JPG">
Once a certain RPM is reached, the diaphram relaxes (as shown in this picture) and changes the length of the intake runner in the manifold. So you'll see it "suck in" and "relax" as the engine is rev'd.....somewhere around 3,000 RPM as I recall and for the 40 valve, there are two RPM's that cause each one to move.
At least I think it's normally sucked in. If your linkage is broken, it's probably because it's seized.
<img src="http://www.audipages.com/Tech_Articles/enginemechanical/tbp12.JPG">
09-09-2008, 07:45 AM
#26
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So I disconnected all those hoses - now what?
Kidding!
Thanks for the picture, should help. If I remember correctly there is a diaphragm that sucks in when the RPM reaches a certain level. Is the one i'm thinking of for the DOHC system?
Thanks for the picture, should help. If I remember correctly there is a diaphragm that sucks in when the RPM reaches a certain level. Is the one i'm thinking of for the DOHC system?
09-09-2008, 01:32 PM
#27
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figurez - I'll be going right thru New Haven tomorrow ~ noon, but...
...I'll be mit bossage.
Tho if you wanted to hook up I figure ya'd have ping'd me 8-).
Have a great trip, enjoy.
Tho if you wanted to hook up I figure ya'd have ping'd me 8-).
Have a great trip, enjoy.
09-09-2008, 04:02 PM
#28
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Here is my Dyno plot for the A8 ~ you can see how the intake makes a huge difference
<center><img src="http://pictureposter.audiworld.com/55364/dyno01.jpg"></center><p>Ok, anyone familiar with how an engine dyno plot SHOULD look, can easily see the huge difference a variable length intake makes.
You can see the jolt at 4200 RPM where the intake valves flop over. Note how power suddenly INCREASES, where it should be dropping off to crap.
You can see the jolt at 4200 RPM where the intake valves flop over. Note how power suddenly INCREASES, where it should be dropping off to crap.
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