EvenOlder

RE: 1990 (S5) Turbo, replacing cats with RB 2.5" downpipe and presilencer, stock ypipe and mufflers, eliminated airpump

So having done my requisite reading about ACV (aka rat's nest) removal and subsequent blockoff, I've noted the following:
1. Buy a thick plate (Racing Beat's)

2. Purchase and use a gasket behind the plate.
Question - Should it be a gasket for the ACV with holes in it, or a solid sheet of gasket material?

3. I've seen blockoff plates (ala Hailer and NZconvertible) with self-installed nipples for vacuum to the Turbo Boost sensor and the Anti-afterburn valve, and a third one for something-
Question - Any input about this, including; plates with the nipples installed, to self-installing nipples, to other lines to Tee off of instead of nippling?

4. Hailers mentioned accomodating a checkvalve- does this mean grinding a divot on the inner face of the plate?

5. Are there any other issues that are S5 specific I should be aware of?

Thanks, I hope to get it right the first time and perhaps do a writeup for us poor S5ers who are generally left out.

steve

arghx

iTrader: (3)

I have an s4 and I don't know if there are any specific s5 issues here, but what I can say is that ACV blockoff plates love to leak boost in the upper left corner of the plate. I have mine installed with permatex ultra black RTV and it doesn't leak, but only because I used a pressure tester to verify http://www.boostpro.net/prodtester.html . I had an old OEM gasket on there that was leaking but the RTV did the trick.

I also have my ACV blockoff plate drilled and tapped for a source that I use for my blowoff valve. There are a few small holes behind the blockoff plate that go into the runners of the UIM... I have mine tapped into one of the holes that's toward the front runners (might make more sense when you pull off the ACV and see what it looks like). Use a 1/8 NPT tap (I had a 1/8 NPT--> 3/16" barb fitting) , and I forget what size drillbit you need to drill that hole, but it's a decent size.

I'm not sure what the checkvalve would be for if you are eliminating the ACV. And if you are pulling the rat's nest, why do you care about the anti afterburn valve? isn't that built into the turbo ACV anyway?

NZConvertible

Or make you own. 3mm (1/8") thick minimum. Easy and rewarding.

Absolutely. When I installed mine I reused the original gasket and it didn't leak. Later I replaced it with sealant and it leaked. I replaced the sealant with a gasket I cut from gasket paper and it hasn't leaked since.

Doesn't matter, it makes no difference. Unless you need the holes, in which case it does...

The AAV is built into the ACV that you've removed. I installed just one, for the MAP sensor. The BOV already has a handy nipple just below and behind the BAC valve. You can install two or three nipples if you wish to connect two or three things. Up to you.

I've never seen anyone offer plates with nipples for sale, so it'll be DIY. Tee's are okay, but not as good IMO. Nippling is good...

Yes, but the check valve is completely redundant so you might as well throw it away.

Nope, it's the same for S4 and S5.

EvenOlder

Thanks for the replies- just looking to clarify something-
Regarding the BOV nipple below and behind the BAC valve:
1. Can a single "Teed" vac line run from that nipple to the pressure sensor AND the turbo boost sensor?
IE; the pressure sensor and turbo boost sensor are the only things that need a vac line after the ACV removal?

2. What about removing the airpump, blocking off the air-in port from the airpump on the ACV, sealing up unused pipes (to emissions) on the ACV, and leaving the now slimmer ACV in place?

Thanks,
steve

EvenOlder

anyone?

NZConvertible

There is only one manifold pressure sensor. You've just used different names for the same thing.

Well it won't actually be any slimmer, and it's pretty pointless. There's no advantage to removing some of the system and leaving some still in place.

HAILERS

About my jpg of my blockoff plate for the ACV: The jpg shows three nipples and also a reference to anti afterburn valve for the two nipples to the left. I meant that reference to mean that those two nipples are Located opposite the feed holes that Went to the anti after burn valve on the ACV its self. Those feed holes lead directly to the middle intake runners and are a very good source of vacuum.

You leave the checkvalve in so it does not get lost or tossed. You'll be needing it in the future and it will be THERE behind the blockoff plate and not laying behind the tool shed or worse.

Make your own gasket from gasket paper from the auto store. Cheap. Only holes would be for the nipples on the plate used for vacuum.

EvenOlder

you know i wuz checkin' yo pics Hailers.
i'm still not sold on trying to drill and tap the RB plate.
i'll decide after receiving it tomorrow.
thanks for the clarification.
steve