924Board.org

[endwrench]

OK, this may be of some interest to you guys who are considering an EFI conversion or just upsizing to an Audi TB. Fisrt you can see the difference in size between the 2 TB's.





I'm doing this because I am supercharged and I figured it may be worth it. I understand it may not be a great mod for standard NA motors but to each their own. This TPS conversion still applies to the stock TB. First thing you need to do is remove the return spring setup. Grind the end of the shaft off with a bench grinder or what ever you have.



After this you need to pry and pull all the stuff off.



Mark and cut the shaft leaving exactly 1"



Making sure the throttle is closed, draw a line thru the center of the shaft perpindicular to the base.



If you use a wide felt tip pen, this will give you a pretty good guide as to how far you need to grind and file the shaft. I used both a grinder and hand files. The knifed edge is about 1\2" long and an 1\8" wide. Narrow is better.



Now is the hard part for most. You need to fabricate a spacer for the TPS. It needs to hold it center on the shaft so it should really be done on a lathe. I would be glad to supply these to anyone for $5. It needs to be .700" long and look like this.





After you have the bushing you can line up where the holes need to be drilled and tapped for the screws. I used #10x24 screws cut to length. I would cut the boss off next to the right side screw before drilling and tapping. Mine was off center due to not doing this. It works fine.



The TPS I found to work with this is from an 85-86 Dodge 2.2L Throttle body injected engine. Not PORT. The hardest part of finding a TPS was finding one that turned in the correct direction. Otherwise many others would work with this mod. NAPA Part # 2-1915. Iff you look at this new one you will see the holes are not slotted for adjustment. You can also see it is made of plastic and is easily slotted with a drill, dremel or zip tool.



Here is what it looks like mounted up.



On to mounting it to the intake. It will bolt directly up and function but it is shrouded. You can see in this picture were I colered in the part I am grinding out.



This is after.



And this is what it looks like after mounting it and my new 44lb injectors, fuel rail, insulated inserts and smaller blower pulley!! Time to start tuning.



Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

[Joes924Racer]

awesome dude. I mean endwrench.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[Min]

Awesome writeup endwrench. I figure I should mention however that there is other ways of doing this sort of thing as well. For example, if your running a megasquirt, you can run without a tps. Which is what I'm going to be doing. You can also get yourself whats called a string pot. http://www.celesco.com/ which you can just hook onto the throttle linkage.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[P924]

Nice... and how many horsepower does it make with the supercharger?
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924 1981
911T 2.2

[endwrench]

I like the "string pot" idea. It would definetly be easier. The only reason I do not like the idea of using the MAP instead of TPS would be cold start tuning. After you are tuned it may work well but I have had to use the "clear flood" mode several times during tuning. I think this can only be used with a TPS. Not sure though.

I have no idea how much HP. Just MORE!

Todd

[Min]

Your right, you lose flood clear when not using a tps. I'm going to hook flood clear up to a switch. So I can just flick it on if I need flood clear mode. After its all tuned it shouldn't be a issue.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[macBdog]

Ok so if you remove those springs to mount the tps, what returns the throttle to closed?
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1979 931 with a 350 chev
1973 911E with EFI

[endwrench]

[sequential]

Todd,
Nice ! It was good to do the TPS, the only way is the correct way , others who don't will at a later date as they pay the price for shortcuts..

How much boost currently. do the drivability then find a dyno for the full power stuff, it will be safer and better.
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928 gts prototype
baby blue engine block
steam in 1,2,3,4 sometimes
cold star issues while on stands
112 whp with new 4 valve head and MIS 2

[endwrench]