Intake Tubes
#1
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Thread Starter
Intake Tubes
What is the purpose of the intake tubes being connected to the cam belt housings ??
How critical is it that they be connected ??
How critical is it that they be connected ??
#2
Rennlist Member
With all of the gears, sprokets, bearings and pulleys spinning around under the front engine cover it is like a super charger. The openings are to direct that air pressure to the induction system.
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928FIXER (01-14-2020)
#4
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I thought it was to create a venturi effect so that local production of ozone around the timing belt is vented up and out of the TB covers, to prolong the life of the belt. Or perhaps just cooling air, for the same intent.
#5
Burning Brakes
This area is not sealed like a distributor. (Where the Ozone issues were discovered on the twin dizzy 964)
#6
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slownrusty (01-15-2020)
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#9
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i thought the hole was where you shone the timing light?
cooling and ventilation of the cam belt area. They were designed that way for a reason...don't see why yours wouldn't be connected if you have the stock tubes as there is a hole in them for the cover to begin with.
#10
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#12
Nordschleife Master
My understanding is that the partial vacuum in the tubes pulls air through the TB system. Cooling? Removing 'bad air'? Something else?
No clue.
However, the early 944 had a similar setup, with a tube going from the air cleaner housing to the TB cover.
Later 944s didn't have it.
I would guess that it's not super critical. Lots of super charged cars go without it, and they don't seem to have issues.
But I always make sure my tubes go back over the 'timing belt inspection holes'. And I put the tube back on my 944, even though the WSM says it's ok to delete it and plug the hole in the air filter housing.
No clue.
However, the early 944 had a similar setup, with a tube going from the air cleaner housing to the TB cover.
Later 944s didn't have it.
I would guess that it's not super critical. Lots of super charged cars go without it, and they don't seem to have issues.
But I always make sure my tubes go back over the 'timing belt inspection holes'. And I put the tube back on my 944, even though the WSM says it's ok to delete it and plug the hole in the air filter housing.
#13
Former Vendor
My understanding is that the partial vacuum in the tubes pulls air through the TB system. Cooling? Removing 'bad air'? Something else?
No clue.
However, the early 944 had a similar setup, with a tube going from the air cleaner housing to the TB cover.
Later 944s didn't have it.
I would guess that it's not super critical. Lots of super charged cars go without it, and they don't seem to have issues.
But I always make sure my tubes go back over the 'timing belt inspection holes'. And I put the tube back on my 944, even though the WSM says it's ok to delete it and plug the hole in the air filter housing.
No clue.
However, the early 944 had a similar setup, with a tube going from the air cleaner housing to the TB cover.
Later 944s didn't have it.
I would guess that it's not super critical. Lots of super charged cars go without it, and they don't seem to have issues.
But I always make sure my tubes go back over the 'timing belt inspection holes'. And I put the tube back on my 944, even though the WSM says it's ok to delete it and plug the hole in the air filter housing.
#14
RL Community Team
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Install supercharger setup leaving ports open. Drive car this way for 4 years and note any negative effects on cam gears or belt wear. Nothing noted.
Seems to me there's enough turbulence inside those covers that heat, ozone, or whatever can escape through the open holes even without a vacuum draw from the intake tubes. I think Porken has the right idea that they're for checking timing without having to remove anything except the intake tubes. Maybe Porsche made them collared ports so coolant or oil leaks couldn't then get through the holes and onto the belts?