924Board.org

datatrain · Posted: Fri May 16, 2008 5:24 am Post subject: Purpose of Vacuum Amplifier

I could never figure out what this thing does. Since there is a vacuum tank under the fender why the amplifier and what is it amplifying and for what ?

Dave

Paul · Posted: Fri May 16, 2008 10:59 am Post subject:

EGR Valve...
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Paul · Posted: Fri May 16, 2008 11:00 am Post subject:

The tank under the left front fender is a charcoal tank that is used to recover gasoline fumes.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Paul, I think on earlier cars there was a funky vacuum reservoir on the passenger side (or driver side for RHD car). It looks like a bunch of spheres attached all together, and it is in the mirror location as the charcoal cannister. These earlier cars also had the vacuum amplifier, which is the funky cylinder-with-sphere-on-the-end that is usually bolted to the frame rail in the engine compartment.
_________________
erstwhile owner of just about every 924 variant ever made

Paul · Posted: Fri May 16, 2008 12:12 pm Post subject:

Yes I had one of those on the 77 I bought new, but the 3 sphere reservoir was mounted beside the battery, but according this site's FAQs, they were also mounted in the right hand fender well....
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

datatrain · Posted: Fri May 16, 2008 12:30 pm Post subject:

Well your almost correct. The vacuum chamber is on the passenger side and the vac amplifier is near the battery. So what's it do ?

Thnx
DAve

Paul · Posted: Fri May 16, 2008 12:38 pm Post subject:

Opens the EGR valve.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

datatrain · Posted: Fri May 16, 2008 1:54 pm Post subject:

Thanks.

DAve

Smoothie · Posted: Fri May 16, 2008 2:39 pm Post subject:

Yeah, it doesn't really "amplify".. The part that's called "vacuum amplifier" is more like a vacuum-operated vacuum switch. Together with the reservoir you have something that could -almost- correctly be called "vacuum amplifier", as it provides a source of relatively high vacuum when needed to open the EGR, even when manifold vacuum is low, as in during full throttle or accelleration.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox