924Board.org

[CBass]

Snapped a few pics of my 52mm throttle body from a MK2 Jetta on my 931 manifold the other day...

http://members.rennlist.com/sbcspeed/HPIM0319.JPG

http://members.rennlist.com/sbcspeed/HPIM0320.JPG

http://members.rennlist.com/sbcspeed/HPIM0321.JPG

The linkage should work without modification, it pulls in the right direction, and it has about the same stroke as the 924 linkage so the pedal feel should be about the same. There is a mechanical idle adjust screw, secured by an 8mm nut and adjusted with a standard flat screwdriver.

http://members.rennlist.com/sbcspeed/HPIM0322.JPG

http://members.rennlist.com/sbcspeed/HPIM0323.JPG

http://members.rennlist.com/sbcspeed/HPIM0324.JPG


There are a few minor differences, there is only one vacuum tap ahead of the throttle blades, but it's large enough that it could be "tee'd" to preserve the original vacuum layout. It has an integral air bypass around the primary blade, adjusted by a little screw on the side, not sure if you'd want to use this in conjunction with an AAV, or if would work well enough to replace it, I'll figure that out later. There is a large post blade vacuum tap as well.

In picture 34, you can barely see the small hole in the primary throtte tunnel that draws the air around the blade for hte idle bypass.

http://members.rennlist.com/sbcspeed/HPIM0329.JPG

http://members.rennlist.com/sbcspeed/HPIM0330.JPG

http://members.rennlist.com/sbcspeed/HPIM0331.JPG

http://members.rennlist.com/sbcspeed/HPIM0332.JPG

http://members.rennlist.com/sbcspeed/HPIM0333.JPG

http://members.rennlist.com/sbcspeed/HPIM0334.JPG





To bolt this t/b on, you'll have to port the intake manifold to match the gasket, you can see in the pictures that there is a lip all around the opening that can be ground away.

http://members.rennlist.com/sbcspeed/HPIM0325.JPG

http://members.rennlist.com/sbcspeed/HPIM0326.JPG

http://members.rennlist.com/sbcspeed/HPIM0327.JPG

http://members.rennlist.com/sbcspeed/HPIM0328.JPG
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'81 931 in various states of assembly

[CBass]

Asked around my VW sources, and I've learned that the MK1/MK2 guys who convert to standalone EFI like megasquirt largely use the Passat 2.0 16v throttle body from an automatic passat, 91-93. It bolts on to the MK2 cars, which as I've demonstrated with pictures bolts on to our cars. the throttle cable pulls in mostly teh same direction as the 924, it's on a bit of an angle though, but I'm sure that can be worked around. It comes with a potentiometer stock.

This throttle body is identical to the G60 Corrado Digifant throttle body, complete with throttle position sensor. I'm not sure whether it's Digi 1 or Digi 2, I'm not really up on my VW EFI. I'll see if I can get my brother to snap some pics of his Passat 16v throttle body. IIRC, there are two vacuum lines that come off of the bottom, but I don't know whether they are before the blades or after.
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'81 931 in various states of assembly

[CBass]

Ok, put my 931 throttle body and my MK2 52mm t/b side by side, and compared. The linkage is identical for the two, so the lower linkage with teh WOT and CT switches can be removed from the Porsche t/b and fitted to the 52mm VW t/b. I'll take pics when I do this, but that's to come later.
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'81 931 in various states of assembly

[gepetto143]

Corrado G60 uses Digi1

Digi2 is found on MK2 1.8 8v 89/90 to 92
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1974 Porsche 914-4
1984 VW Jetta TD

[Eturbo924]

That looks like the same one I put on my 1982 924. I did have to modify the linkage to shorten it... or I would not have been able to close the hood of my car. Even with it cut down it was still touching my hood.

I ground down the post as much as I could and it now seems to work.

Check out my site.

http://www.geocities.com/eturbo924/throttlebody.html
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1982 924
1992 968
2003 C4S
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[CBass]

Yeup, nice throttle body ain't it

I'm working on putting a TPS on teh bottom of it, I have one from a Buick V6 that will fit on the keyed shaft, and is very easy to mount because of it's linkage design.
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'81 931 in various states of assembly

[morghen]

the first pics show the MK2 TB???

the pics are big...and i only took a look at a few of them....but...this TB looks exactly like the one i have on my 924.....it came like this...or yours is looking exactly the same and its actualy bigger ?
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Supercharger and EFI kits
https://www.the924.com

[CBass]

The 52mm throttle bodies are easily identified by the size of their secondary throttle plate, which is much larger than the primary plate(the smaller plate). You might already have an Audi throttle body on your car, it is a popular upgrade.
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'81 931 in various states of assembly

[-nick]

Hey CBass-
Finally got around to measuring the extra 944 TB I have. It's a square pattern- 7cm between bolt holes (10mm diagonally).

I'm curious if this matches the bolt pattern on the s2 931 intake?

nick

[CBass]

Excellent, I'll measure this next time I'm in Pitt Meadows. My brother's 931 S2 is in a junkyard there
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'81 931 in various states of assembly

[augidog]

I threw in my Audi throttle body in today. I opened up the intake with dremel bits and polished it. It was ez work as the intake sands quickly. In fact I used a drill with a pack of dremel sandpaper bits-worked fine.
When I started it up my timing was way advanced (probably because a vacuum leak on the old TB),I set the timing back to oem specs.
The road test proved sluggish, maybe too much air with the mix that I was previously set at. I had to switch the vacuum port connection around because as with the oem78 throttle body, there are two ports which are in front and back of the plates. I had the wrong one capped.


I'm going top have to play with mix now because it won't hold a 950-rpm idle. It idles around 800 without touching the mix.
I know in the future it will be better but as of right now it needs a lot of tuning to come back to the pickup of the 1980 TB I had on.
Road test show a quicker pedal response to 0 vacuum so I'm hopeful. I'll adjust fuel /air mix when I get my new 02 sensor this week but for now I'll tweak it richer to raise the idle.
It is not a quick bolt on upgrade like I originally thought.
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.