# 3A Swap



## twilly.wills (Feb 24, 2011)

Tried posting in the hybrid/swap forum but no feedback

So I am working with a 2L 3A audi motor I bought off craigslist, and the 1.8 8v GX motor I have pulled from my mk1. What should be my best option for cheap hp? I'm looking at using the 3A block with my 1.8 head. Possibly decking the head or bore the block a little? Whats the best route? The 3A already came with an autotech cam and hd valve springs which should swap into the 1.8 head I believe. Any input would be appreciated, Thanks.


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## ziddey (Apr 16, 2006)

A1s did not come with the GX motor, so I'm assuming it's a transplant.

I don't understand why you want to put the GX head on the 3A block. Why not just drop the whole 3A in? I'm imagining the 3A has bigger valves (although I'm not sure of differences between the 3A head and Digifant heads) than the GX.

As far as power, upgrade to a 4-2-1 exhaust manifold / dual downpipe.


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## WaterWheels (Aug 14, 2005)

OK, why swap on the 1.8 cylinder head? I understand people putting a 2.0L bottom end under their 1.8 head to increase the displacement. You seem to indicate you already have a complete 2.0L 3A so what is the reason for thinking about doing a head swap? Using the complete 3A in place of the GX is going to increase the torque a lot, and of course horsepower along with it, as long as you have it tuned correctly. People like to talk/hear horsepower being thrown about so here you go. The GX is what, 90hp? The 3A is what 115hp? If I'm off a little it will be just a little so you are talking a minimum, you said it also comes with a sport camshaft, 25hp increase (almost 30%). The engine weighs about the same so that ain't a bad increase really. Just picture in your head your mk1 with 30% more power and all you did was swap over engines and get it running good.


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## twilly.wills (Feb 24, 2011)

Yes the GX was a swap from the previous owner. The reason for using the 1.8 head would be so I could use all the same fuel injection parts I already am. Also the 3A came from an older audi 80 or 90. They had the motors sideways and everything was moved around. Im not sure if i have all of the right fuel injection parts. I know the injectors come through the intake manifold on the 3A instead of in front of it right into the head like on my GX. also idk wouldnt the 1.8 head on the 2.0l block make for higher compression than the 2.0l head? Im not sure about the valves being bigger I'll have to measure them. Thanks for the input so far guys, I just want to make sure I get the most out of this while I have it all apart. :thumbup:


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## ziddey (Apr 16, 2006)

Oh right. I forgot about the injectors. I don't know if it's possible to use CIS injectors with the 3A intake manifold. Maybe CIS Motronic injectors are a different size?

The impact from the difference in valve size is pretty negligible.

The 3A was used in a longitudinal setup, but this affects more the block than the head. Swap over all the motor mount brackets, accessory brackets, etc from your old GX block.

I believe your old distributor should drop right into the 3A block, unless you're looking to adapt a knock sensing setup.


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## twilly.wills (Feb 24, 2011)

Yeah thats why if it wont make much of a different I'll stick with my 1.8 head since I know my fuel system works. And yes I will be looking to run a knock box setup to eliminate the vacuume lines and simplify things. Also if I decide to do anything to up the compression the knock box will be needed


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## ABA Scirocco (May 30, 2001)

Putting a 3a block under a 1.8L head is not all that different from just installing a normal 1.8L engine, most of the external dimensions of the 3a block are identical to a 1.8L block, to only difference you need to work about is the distributor, have a look at MY WEBSITE, it deals specifically with using a 1.8L head on an ABA block but everything I said there concerning the distributor applies equally to 3A block as well.


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## twilly.wills (Feb 24, 2011)

The 3A already comes with the knock box distributer stock.


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## ABA Scirocco (May 30, 2001)

So you got the knock box and it's associated wiring when you bought the engine? If so, it's a no brainer, use the distributor that came with the 3A and install the knock box system in your MK1, everything you need to know to install the knock box came be found at http://www.driversfound.com/scirocco/techtips/engine/knocksensor/.


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## twilly.wills (Feb 24, 2011)

Yes I believe I have the right box. Also I know about the block off plate that I will need


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## type17 (Feb 13, 2006)

3A distributor has a bigger neck, so you definitely need that, unless you buy a special collar from tt for the 1.8 distributor. Block off plate and soft plug are easy. First swap I did, I used the 1.8 head because I had a nice cam in it already. Second time, I swapped the whole motor, no issues whatsoever. But, the cold start valve was really close to the fresh air plennum. Rabbit will just clear,k1 Scirocco, not sure. Make sure your knock box, if it's a separate umit, is for the 2.0, or else you're gonna have to compensate ignition timing. I could never figure it out in my Scirocco. Although, running premium made the ping less severe.

Congrats on the swap, that is a fun motor for essentially plug and play.


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## twilly.wills (Feb 24, 2011)

Alright i will double check my box for sure but i do have the 3A dist. How about the heavy duty valve springs and cam i have in the 2.0 head? Direct swap into the 1.8 head? anything i should freshen up or consider having done to the 1.8 head keeping a college students budget in mind. ? My complete GX motor was in good running condi tion before pulled. Good compression, no burning oil, no issues basically.


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## ziddey (Apr 16, 2006)

should be the same.

as for reducing vacuum lines, you'd be moving the line from the distributor's vacuum advance canister to the knock box itself. Still "need" it.


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## twilly.wills (Feb 24, 2011)

Yeah just one line to the box. I can hide it to wherever I mount the box


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## nairmac (Jan 22, 2004)

Here are a couple of pics of my 3A with a 2H head. Same idea...



















I knocked the pin out of a JH distributor distributor and replaced the gear with the 3A one. I also used a thick nylon washer under the distributor (above the gear) to center the distributor and serve as an adapter. Block off plate is from Techtonics and I never used a knock sensor because I'm low compression and never needed it.


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## ziddey (Apr 16, 2006)

Nice. Any details about the nylon washer? Sounds like it'd be a much cheaper solution than the aluminum adapter TT sells


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## nairmac (Jan 22, 2004)

ziddey said:


> Nice. Any details about the nylon washer? Sounds like it'd be a much cheaper solution than the aluminum adapter TT sells


It has to be put onto the distributor shaft while the gear is off. The one I ended up using (after some test fitting and such) is about 1/4 inch thick and required me boring out the center to the diameter if the distributor shaft. I don't remember the diameter of the washer or the hole in the block is, but you can easily shave the nylon down to get it close enough. I put a bead of high-temp silicone on the block around the edge of the hole so that the washer wouldn't twist when adjusting timing. It's been there for 6 years and 20,000+ miles, so yeah, it works fine. :thumbup:


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## ziddey (Apr 16, 2006)

Awesome. That information could save people quite a bit of money-- TT sells an adapter bushing for $30 http://techtonicstuning.com/main/index.php?main_page=product_info&cPath=2_11_5_248&products_id=1370


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## WaterWheels (Aug 14, 2005)

twilly.wills said:


> . . . The reason for using the 1.8 head would be so I could use all the same fuel injection parts I already am. Also the 3A came from an older audi 80 or 90. They had the motors sideways and everything was moved around.


Just to maybe make things easier or to give some food for thought, the 3A used CIS and the intake looks exactly like your current one except for the head to manifold mating surface. Yes, the injectors are in the manifold, but the injector holders screw into the manifold (or push in?). They are an Audi only part but I'm sure only cost maybe $4 max each. The injectors the Audi used were the 10mm like in the CIS-Motronic engines, but the 12mm ones will fit just like they do in VW engines. Might want to think about using the complete long block. Intake ports seem better also on the 3A also.


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## twilly.wills (Feb 24, 2011)

So all I would be doing would be getting different injector ends for my existing CIS setup? I mean I'm already tearing everything apart so I will use whatever head gets me better power. But good to know I can make the 3A head work with my old CIS though. :thumbup:


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## twilly.wills (Feb 24, 2011)

And I already have the 3A distributor so I wont need to worry about that.


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## LT1M21Stingray (Sep 14, 2006)

twilly.wills said:


> ... But good to know I can make the 3A head work with my old CIS though. :thumbup:


 3A head + 3A intake manifold + CIS. 










The 3A head has the big valves.


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## twilly.wills (Feb 24, 2011)

So did you get different injectors to work through the 3a head? Looks good ^^:thumbup: I'm excited to see what kind of a difference this engine will make.,


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## LT1M21Stingray (Sep 14, 2006)

twilly.wills said:


> So did you get different injectors to work through the 3a head? Looks good ^^:thumbup:


 IIRC they are the same except for the threads to the fuel lines which is why I used the original CIS injectors so I could use the original fuel lines.


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## twilly.wills (Feb 24, 2011)

So I don't change anything? I didn't know if because they go through the intake mani they are somehow different than the GX ones that go straight into the head. 

Thanks.


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## LT1M21Stingray (Sep 14, 2006)

Here are some pictures. 



















The injectors are held by two plastic holders, which makes it much easier to remove them, but other than that, they will fit.


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## Glegor (Mar 31, 2008)

1.5/6/7/8 dizzys dont fit in 2.0 blocks...


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## ABA Scirocco (May 30, 2001)

Glegor said:


> 1.5/6/7/8 dizzys dont fit in 2.0 blocks...


Essentially correct but they can be modified to work in a 2.0L block.

In this picture, you see a 2.0L distributor (on left) next to a 1.8L distributor, the diameter of the 2.0L distributor where it meets the block is larger than the 1.8, the gear is also larger.


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## nairmac (Jan 22, 2004)

Yeah, I run a 1.8 vacuum advance distributor in my 3A with the 3A gear on it.


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