Need P/N of redesigned Porsche Airbox

[hbkramer]

I am trying to confirm if the airbox I just purchased is the redesigned box that does not require a pop off valve. The part number is 911– one zero– 106– 20.

It appears to be the same one that's on the car (exploded w popoff valve )that has with the six steel spiders protruding into the intake snorkels from the mixture chamber.

Can anyone confirm if this is the new style that does not require the pop off valve. Thank you.

[hbkramer]

actual p/n on new box reads as follows: 911 110 106 20.

[Flat6pac]

The one with the spider inside is the new one. I doubt there would be another design as CIS has been gone from production for 32 years.
Still do a pop off valve with that design.
Bruce

[hbkramer]

Thanks Bruce .
The reason for my question is that the one that was in the car also has the spider and someone had added the pop off valve and I still exploded it. I was under the impression that the Metal spider design did not require a pop off valve and was somewhat immune to blowing apart. It appears not.

So the next question is should I reinstall the pop off valve , I am leaning in that direction.

PS the manufactured date of the one I just purchased is 7/2011. I think that would indicate that it's also the new design.

[Flat6pac]

Why take the chance, install the pop off valve, just pop it out on the old one, 2 inch round hole some JBWeld. That's as good an insurance policy as you'll find
These usually pop back because you're too lean.
Bruce

[boyt911sc]

Originally Posted by hbkramer

Thanks Bruce .
The reason for my question is that the one that was in the car also has the spider and someone had added the pop off valve and I still exploded it. I was under the impression that the Metal spider design did not require a pop off valve and was somewhat immune to blowing apart. It appears not.

So the next question is should I reinstall the pop off valve , I am leaning in that direction.

PS the manufactured date of the one I just purchased is 7/2011. I think that would indicate that it's also the new design.

HBK,

You probably read some posts by a well known member of this forum that does not believe in using pop valve in CIS airbox. The later CIS airbox with spider plumbing improves the distribution of cold injected fuel by the CSV and thus reducing backfire. But it does not eliminate or prevent occurrence of backfire in a CIS engine with unbalanced fuel mixture. All you need is one strong unwanted backfire and your air box could be compromised. Even with a pop valve, a very severe or strong backfire could damage your air box.

I had purchased several CIS air boxes that were supposedly good and working. They had spider plumbings and pop off valves. Half of them were cracked and would need a lot of work to get them sealed. I would be reluctant to work on a CIS engine without a pop off valve.

The pop off valve should be maintained and checked regularly. It got to be sealing and not leaking. This is the main problem with the POV and often neglected by people until it is too late. It takes less than a minute to test a POV for leak if you doubt your POV is leaking. Imagine you have some unwanted mild backfire with no POV and quess what will be compromised?

Tony

[hbkramer]

Amen,
Agree 110% .
Bruce Tony, Thank you for the excellent feedback, an ounce of prevention is worth a pound of cure.
My previous airbox with the improved fuel circuit/spyder assembly is evidence that the pop off valve does not necessarily ensure it will survive a substantial backfire . MY MISTAKE that led to the box separating at the seams was a shot of eather when I had spark and no fuel , trying to start a freshly rebuilt 3.0.
The smart money would have troubleshoot the lack of fuel, which in my case was due to a faulty 25 amp fuse -it crumbled as I removed it from the fuse box. After blowing the air box then checking for fuel, The pump spun right up. Expensive and time consuming lesson.LIVE AND LEARN.


So Jb weld is the preferred sealant for the pov?


Thanks !!
Bruce
Allentown Pa.

[Flat6pac]

Anything of the composit materials will do the job, just happens I haveJB weld on the shelf.
Bruce

[boyt911sc]

Originally Posted by hbkramer

Amen,
Agree 110% .
Bruce Tony, Thank you for the excellent feedback, an ounce of prevention is worth a pound of cure.
My previous airbox with the improved fuel circuit/spyder assembly is evidence that the pop off valve does not necessarily ensure it will survive a substantial backfire . MY MISTAKE that led to the box separating at the seams was a shot of eather when I had spark and no fuel , trying to start a freshly rebuilt 3.0.
The smart money would have troubleshoot the lack of fuel, which in my case was due to a faulty 25 amp fuse -it crumbled as I removed it from the fuse box. After blowing the air box then checking for fuel, The pump spun right up. Expensive and time consuming lesson.LIVE AND LEARN.


So Jb weld is the preferred sealant for the pov?


Thanks !!
Bruce
Allentown Pa.

Bruce,

When you were dong the start-up preparation for the newly rebuilt motor, did you hook up a pressure gauge and ran the FP? This should be a routine procedure for start-ups and would save you from a lot of aggravation. Try to do this for your next start-up. And don't forget to test the integrity of the installed POV. Keep us posted.

Tony

[3.0schotrod]

I know that this is an old thread, but what year did the metal spider plumbing start. I have a 79, will it have the spider plumbing ?

[Flat6pac]

Started in the early 80s
Bruce