924Board.org

[DZGunner]

I've been looking at different throttle bodies and trying to see if i could find a cheap one to fit my 80 turbo. I've read alot that people get the Audi 5000 throttle body, but i think i also read there are some differences in the secondary and primary ports in those (diameter wise), and that it would be beneficial to port the intake a little too to match the larger ports. How much do these throttle bodies go for and where can I find them?

This made me look at the S2 intakes. I wanted to know if the S2 throttle body (the one with the big o-ring) is better than the Audi one. I'm just looking around at all my choices and what would be the best bang for my buck.
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1979 924 (Daily driver EFI)
1979 924 Sebring
1977 924
1977 924 (Parts)

[Grenadiers]

The S2 option requires the big o-ring as you mentioned, and someone might correct me if I'm wrong, but I haven't been able to find these for sale anywhere. And, you'll need the S2 charge pipe to the turbo. Not sure it's worth it.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[ideola]

Only place to find 5000 throttle body is a salvage yard. I've not had much success finding a reliable source.

The big advantage of the S2 setup is you eliminate the S1 rubber boot in favor of a hard connection. If you go with the 5000 TB, I strongly recommend replacing the OEM rubber boot with a section of silicone tubing as the 5000 orifice is larger enough than the OEM TB as to increase the likelihood of boost leaks at that interface.

To do the S2 conversion, you need the intake, the charge tube, the throttle body complete with throttle position switch, the big black rubber exterior seal (seals charge tube to TB and NLA from Porsche), and the linkage assembly that bolts to the mani. You also need to do some splicing to convert the wiring from the S1 micro switches to the S2 TPS.

My vote is the S2 setup. Not that hard of a conversion, single throat TB is better than the Audi unit for forced induction, and uses all OEM components.

FWIW, the 2.5L (early 944 and 924S) use the same TB casting as the S2, although some of the linkage and spring arrangement is different. You can use a 2.5L TB in a pinch and transfer parts from the Audi TB. You will need to order the correct S2 931TPS which is still available from Porsche.

The other big advantage of S2 is that the TB is rebuildable. I commissioned Bruce Arnn to make an S2 specific rebuild kit, I suspect you can contact him directly to order one. Strongly recommend doing this as every S2 TB I've had exhibited crumbling o rings on the shaft, causing boost leaks. We tried to make a rebuild kit for the S1 but it used integral bushes that were not easily or affordable reproduced. For this reason alone, if you plan to increase boost, you should convert to the S2.

There are two additional TB seals you will need: TB to intake (same as used on 944/924S and still available from Porsche), and the inner o ring that goes on the groove of the TB to seal it inside the charge tube. This latter o ring is NLA, but the dims are listed in PET, so you can look those up and order a suitable replacement from a variety of o ring suppliers.
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erstwhile owner of just about every 924 variant ever made

[DZGunner]

If i can ever find a full S2 set up I'll have to come back and ask about the switches on the bottom of the throttle body. I saw that in some posts but didn't pay too much mind to it, as long as it's possible I'll worry about it when I can find these elusive parts. Thanks for the input guys. My search begins.
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1979 924 (Daily driver EFI)
1979 924 Sebring
1977 924
1977 924 (Parts)

[ideola]

"Big bore" throttle body cross reference:
Neuspeed 3-65.10.xx
Audi 5000 85, 86 non turbo
VW Fox 91 -93
VW Cabrolet 91 -93
VW Golf MK2 8v
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erstwhile owner of just about every 924 variant ever made