Intake Manifold flap lock in long position thread

A6 All/ S6 All
#1

(I was following this thread V10 Intake manifold flap delete v. lock and Cleaning before it jumped into the actual cleaning. I just want to bring it back to the IM mod)

Apparently, my mechanic has spare time during this c19 lockdown, so he’s willing to work with me on getting this mod done while he replaces the leaking front crank seal. So I’m gonna try to get some sheet metal and epoxy and lock my gutted IM with the runners in long position. (see: )

I just wanted to confirm a few points:

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  1. Is this a rough template for the SS cutout (i.e. open to the long runners)?
  2. I can find 304 Stainless sheet metal locally in thicknesses from 0.2mm to 2mm. What do I want?
  3. Is this what I need for epoxy? JB Weld HighHeat` or will any 2 part epoxy work (I have gorilla epoxy in the toolbox)?
#2

Sorry I got carried away on my thread :sweat_smile:

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#3

Leaving them down should be on the long runner. Up pushes the air into the top part of the intake and shortens the runner length

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#4

Is the IM where the flaps go made from Aluminum? Should I get aluminum sheet vs any other?

#5

I think whatever metal that is sturdy enough should work

#6

Its made of magnesium but really any material is good to block it off

#7

thanks. here’s what I found on magnesium alloys:

"An investigation was carried out into the galvanic corrosion of magnesium alloy AZ91D in contact with zinc, aluminium alloy A380 and 4150 steel. […] Steel was the worst cathode and aluminium the least aggressive to AZ91D. " https://www.sciencedirect.com/science/article/pii/S0010938X03001902

So I suppose I’ll go with AL sheet and a thick layer of epoxy. How much +/- pressure do you think it needs to withstand? The existing flaps are just plastic…

#8

I’m sending the car to the shop this week. In addition to replacing an aging radiator, I’m gonna try to get the oil cooler o-rings and some water-pump driveshaft o-rings replaced—hopefully that will plug up the slow oils drips from the bottom of the engine.

But I also got 10 of these IM flaps from another member (thanks Ed) and I’m looking at locking my gutted IM into the long runner position.

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That is one of the flaps, along with the JB Weld epoxy.

Before I open up the intake, a question: can I just use a liberal amount of epoxy and glue 10 of these in place? Do I need to do anything else?

#9

If the flaps aren’t complete dust then you can just use the epoxy

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#10

JB works really well. Just make sure it’s temp range is good especially if you don’t have JHM intake spacers.

Make sure you clean off any oil from the flaps. also keep in mind you want full coverage getting the flaps sealed tight in the port. The better the seal the better the hold down the line.

#11

Good idea. I just cleaned the flaps with WD40.

As far as condition here is a snap—the 2 on the left are in the worst condition, the silicone on the others are mostly intact.

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Can I fill the gaps with epoxy or should I use something like permatex? Also, am I applying the epoxy directly to the silicone, or to the mounting brackets on the sides?

#12

Houston, we have a problem…

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I’m just lining things up and it looks like 2 flaps don’t have full coverage. Even so, for the other 8 flaps it doesn’t look like there is enough strength without the mount supports (don’t have them). Finally, there are the 3 holes for each mount that leak through.

Any suggestions?

I have a lot of these fiber reinforced silicone baking mats I can cut up. Thoughts on cutting these up to give the flaps extra coverage? Will it be enough?

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Or plan B is to do something like this. But what material is best?

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#13

So this is happening. I decided to go with plan B, aluminum sheet. After testing a couple of thicknesses, i ended up with a 416x135mm sheet of 0.4mm thickness.

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I’m epoxying the bottom in place first, then tomorrow I’ll glue the “tongues” to the backplate. I hope I don’t accidentally create a add a strange whistle to my IM…

#14

It works! The car was put together with the modified IM and everything is great.

My mechanic marveled at how smoothly the car was idling, and we can only attribute that to the changes in the IM (the only other changes were new o-rings in a dozen places and a new radiator). I’m also relieved that my hack/mod with the sheet metal did not introduce any new whistling sounds.

I only had time for a short test-drive in highway traffic, but the car does seem to be more responsive off the line. Of course, that may be influenced by my relief to just get the car back after months of chasing oil-leaks.

#15

Great idea on the sheet. If you don’t have all of the parts needed that would probably be the next best idea.

You will now see why we over and over and over. Tell people don’t remove the flaps all together. The idle will be better. Your MPG will be better the around town driving will be better. Now under about 4500 rpm your driving the car on the runners that the engineer team wanted them to be.

#16

I have the flaps removed, and the idle is as good as it can get. Even passed the coin test.

Also, on low load it seems that the flaps is in the short position anyway(?).

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It’s just a matter of taste. I get why you would prefer long position but I also understand why some, as myself, prefer the short position.

Driving around the city I just cruise, but when I need to have some fun I put the gear in S and rarely dip under 4200 rpm.
After all we have the Autobahn over here :grimacing:

#17

Kimovich you’re pretty much in the extreme minority. Almost nobody wants to be on the short runner it kills the low end absolutely won’t idle as good as a real intake that functions or an intake with just the long runner. . Your MPG is effected as well as drive ability. Having the flaps removed by far is absolutely least ideal. Your just willing to deal with it as you can still blast and drive above 4500rpm. The other 99% of us rarely drive above 4500 rpm for more than a few seconds.

You took this graph from the study guide. The intake will only shift to short runner when starting and some isolated conditions and those conditions are basically standing long term or mid term idle.

Either way you slice it. I think its impressive to be able to say. That your able to drive and rarely dip under 4200 rpm. I think your totally not aware of how rare that is over there lol… Given that your able to achieve that. I would totally understand your outlook and would probably do the same thing.

#18

My plan is to join you on the autobahn later this fall. Maybe then, I’ll be ready to spring for a proper IM. Until then, I’m with Justincredible—the only time I get to the upper registers is right after the toll gate where I can floor it.

Btw, Kimovitzh, if the car holds together, we’re gonna do the JHM Ecu/tcu tune together.

#19

Don’t agree, it does take some nm’s, surely, but that it would “totally kill it” isn’t the case. In my opinion based on that I have tried both on my car.
The idle is as good as any new car rock solid and at a stable rpm looking in VCDS.
Only rough idle is with that stupid SAI.

We’ve had this discussion a couple of times and you might have had a bad experience with the short intake at some point, I just don’t see that on my car.
I’ve read* that the US cars have a different stock map than the EUs maybe that could cause the difference in our experience?

*Regarding the software, JHM wrote to me:
“ European cars have different software than north american vehicles.” and “ there are alot of differences between north america and ROW. i am not certain the exact differences.”

Regarding the 4200rpm, that’s when I drive for fun. On the back roads on the country side, with new Bilstein coil overs, or at the Autobahn when we go for holiday in Switzerland or France.

Try to floor it going for the top speed, and see the rpm’s fly away, and where they stay.

And Justin, this is in no way me trying to say that the long version is stupid. In no way.
I’m just saying that some like vanilla ice and others like chocolate. :blush:

#20

Where are you located? :slight_smile: